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@ -1,3 +1,5 @@
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翻译中 by小眼儿
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Yes, This Trojan Infects Linux. No, It’s Not The Tuxpocalypse
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================================================================================
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@ -1,3 +1,5 @@
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translating by barney-ro
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2015 will be the year Linux takes over the enterprise (and other predictions)
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||||
================================================================================
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||||
> Jack Wallen removes his rose-colored glasses and peers into the crystal ball to predict what 2015 has in store for Linux.
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||||
@ -62,7 +64,7 @@ What are your predictions for Linux and open source in 2015? Share your thoughts
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||||
via: http://www.techrepublic.com/article/2015-will-be-the-year-linux-takes-over-the-enterprise-and-other-predictions/
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作者：[Jack Wallen][a]
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译者：[译者ID](https://github.com/译者ID)
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译者：[barney-ro](https://github.com/barney-ro)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
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@ -1,3 +1,4 @@
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[translating by KayGuoWhu]
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A brief history of Linux malware
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================================================================================
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A look at some of the worms and viruses and Trojans that have plagued Linux throughout the years.
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How to Backup and Restore Your Apps and PPAs in Ubuntu Using Aptik
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================================================================================
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If you need to reinstall Ubuntu or if you just want to install a new version from scratch, wouldn’t it be useful to have an easy way to reinstall all your apps and settings? You can easily accomplish this using a free tool called Aptik.
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Aptik (Automated Package Backup and Restore), an application available in Ubuntu, Linux Mint, and other Debian- and Ubuntu-based Linux distributions, allows you to backup a list of installed PPAs (Personal Package Archives), which are software repositories, downloaded packages, installed applications and themes, and application settings to an external USB drive, network drive, or a cloud service like Dropbox.
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NOTE: When we say to type something in this article and there are quotes around the text, DO NOT type the quotes, unless we specify otherwise.
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To install Aptik, you must add the PPA. To do so, press Ctrl + Alt + T to open a Terminal window. Type the following text at the prompt and press Enter.
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sudo apt-add-repository –y ppa:teejee2008/ppa
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Type your password when prompted and press Enter.
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Type the following text at the prompt to make sure the repository is up-to-date.
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sudo apt-get update
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When the update is finished, you are ready to install Aptik. Type the following text at the prompt and press Enter.
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sudo apt-get install aptik
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NOTE: You may see some errors about packages that the update failed to fetch. If they are similar to the ones listed on the following image, you should have no problem installing Aptik.
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The progress of the installation displays and then a message displays saying how much disk space will be used. When asked if you want to continue, type a “y” and press Enter.
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When the installation if finished, close the Terminal window by typing “Exit” and pressing Enter, or by clicking the “X” button in the upper-left corner of the window.
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Before running Aptik, you should set up a backup directory on a USB flash drive, a network drive, or on a cloud account, such as Dropbox or Google Drive. For this example, will will use Dropbox.
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Once your backup directory is set up, click the “Search” button at the top of the Unity Launcher bar.
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Type “aptik” in the search box. Results of the search display as you type. When the icon for Aptik displays, click on it to open the application.
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A dialog box displays asking for your password. Enter your password in the edit box and click “OK.”
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The main Aptik window displays. Select “Other…” from the “Backup Directory” drop-down list. This allows you to select the backup directory you created.
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NOTE: The “Open” button to the right of the drop-down list opens the selected directory in a Files Manager window.
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On the “Backup Directory” dialog box, navigate to your backup directory and then click “Open.”
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NOTE: If you haven’t created a backup directory yet, or you want to add a subdirectory in the selected directory, use the “Create Folder” button to create a new directory.
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To backup the list of installed PPAs, click “Backup” to the right of “Software Sources (PPAs).”
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The “Backup Software Sources” dialog box displays. The list of installed packages and the associated PPA for each displays. Select the PPAs you want to backup, or use the “Select All” button to select all the PPAs in the list.
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Click “Backup” to begin the backup process.
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A dialog box displays when the backup is finished telling you the backup was created successfully. Click “OK” to close the dialog box.
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A file named “ppa.list” will be created in the backup directory.
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The next item, “Downloaded Packages (APT Cache)”, is only useful if you are re-installing the same version of Ubuntu. It backs up the packages in your system cache (/var/cache/apt/archives). If you are upgrading your system, you can skip this step because the packages for the new version of the system will be newer than the packages in the system cache.
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Backing up downloaded packages and then restoring them on the re-installed Ubuntu system will save time and Internet bandwidth when the packages are reinstalled. Because the packages will be available in the system cache once you restore them, the download will be skipped and the installation of the packages will complete more quickly.
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If you are reinstalling the same version of your Ubuntu system, click the “Backup” button to the right of “Downloaded Packages (APT Cache)” to backup the packages in the system cache.
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NOTE: When you backup the downloaded packages, there is no secondary dialog box. The packages in your system cache (/var/cache/apt/archives) are copied to an “archives” directory in the backup directory and a dialog box displays when the backup is finished, indicating that the packages were copied successfully.
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There are some packages that are part of your Ubuntu distribution. These are not checked, since they are automatically installed when you install the Ubuntu system. For example, Firefox is a package that is installed by default in Ubuntu and other similar Linux distributions. Therefore, it will not be selected by default.
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Packages that you installed after installing the system, such as the [package for the Chrome web browser][1] or the package containing Aptik (yes, Aptik is automatically selected to back up), are selected by default. This allows you to easily back up the packages that are not included in the system when installed.
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Select the packages you want to back up and de-select the packages you don’t want to backup. Click “Backup” to the right of “Software Selections” to back up the selected top-level packages.
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NOTE: Dependency packages are not included in this backup.
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Two files, named “packages.list” and “packages-installed.list”, are created in the backup directory and a dialog box displays indicating that the backup was created successfully. Click “OK” to close the dialog box.
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NOTE: The “packages-installed.list” file lists all the packages. The “packages.list” file also lists all the packages, but indicates which ones were selected.
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To backup settings for installed applications, click the “Backup” button to the right of “Application Settings” on the main Aptik window. Select the settings you want to back up and click “Backup”.
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NOTE: Click the “Select All” button if you want to back up all application settings.
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The selected settings files are zipped into a file called “app-settings.tar.gz”.
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When the zipping is complete, the zipped file is copied to the backup directory and a dialog box displays telling you that the backups were created successfully. Click “OK” to close the dialog box.
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Themes from the “/usr/share/themes” directory and icons from the “/usr/share/icons” directory can also be backed up. To do so, click the “Backup” button to the right of “Themes and Icons”. The “Backup Themes” dialog box displays with all the themes and icons selected by default. De-select any themes or icons you don’t want to back up and click “Backup.”
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||||
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||||
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The themes are zipped and copied to a “themes” directory in the backup directory and the icons are zipped and copied to an “icons” directory in the backup directory. A dialog box displays telling you that the backups were created successfully. Click “OK” to close the dialog box.
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|
||||
|
||||
|
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Once you’ve completed the desired backups, close Aptik by clicking the “X” button in the upper-left corner of the main window.
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Your backup files are available in the backup directory you chose.
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||||
|
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When you re-install your Ubuntu system or install a new version of Ubuntu, install Aptik on the newly installed system and make the backup files you generated available to the system. Run Aptik and use the “Restore” button for each item to restore your PPAs, applications, packages, settings, themes, and icons.
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||||
--------------------------------------------------------------------------------
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||||
|
||||
via: http://www.howtogeek.com/206454/how-to-backup-and-restore-your-apps-and-ppas-in-ubuntu-using-aptik/
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|
||||
作者：Lori Kaufman
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||||
译者：[译者ID](https://github.com/译者ID)
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校对：[校对者ID](https://github.com/校对者ID)
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|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
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[1]:http://www.howtogeek.com/203768
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@ -1,273 +0,0 @@
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How to configure HTTP load balancer with HAProxy on Linux
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================================================================================
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Increased demand on web based applications and services are putting more and more weight on the shoulders of IT administrators. When faced with unexpected traffic spikes, organic traffic growth, or internal challenges such as hardware failures and urgent maintenance, your web application must remain available, no matter what. Even modern devops and continuous delivery practices can threaten the reliability and consistent performance of your web service.
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|
||||
Unpredictability or inconsistent performance is not something you can afford. But how can we eliminate these downsides? In most cases a proper load balancing solution will do the job. And today I will show you how to set up HTTP load balancer using [HAProxy][1].
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|
||||
### What is HTTP load balancing? ###
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||||
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||||
HTTP load balancing is a networking solution responsible for distributing incoming HTTP or HTTPS traffic among servers hosting the same application content. By balancing application requests across multiple available servers, a load balancer prevents any application server from becoming a single point of failure, thus improving overall application availability and responsiveness. It also allows you to easily scale in/out an application deployment by adding or removing extra application servers with changing workloads.
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||||
|
||||
### Where and when to use load balancing? ###
|
||||
|
||||
As load balancers improve server utilization and maximize availability, you should use it whenever your servers start to be under high loads. Or if you are just planning your architecture for a bigger project, it's a good habit to plan usage of load balancer upfront. It will prove itself useful in the future when you need to scale your environment.
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||||
### What is HAProxy? ###
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||||
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||||
HAProxy is a popular open-source load balancer and proxy for TCP/HTTP servers on GNU/Linux platforms. Designed in a single-threaded event-driven architecture, HAproxy is capable of handling [10G NIC line rate][2] easily, and is being extensively used in many production environments. Its features include automatic health checks, customizable load balancing algorithms, HTTPS/SSL support, session rate limiting, etc.
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||||
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||||
### What are we going to achieve in this tutorial? ###
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||||
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||||
In this tutorial, we will go through the process of configuring a HAProxy-based load balancer for HTTP web servers.
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||||
### Prerequisites ###
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||||
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||||
You will need at least one, or preferably two web servers to verify functionality of your load balancer. We assume that backend HTTP web servers are already [up and running][3].
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||||
|
||||
### Install HAProxy on Linux ###
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||||
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||||
For most distributions, we can install HAProxy using your distribution's package manager.
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||||
|
||||
#### Install HAProxy on Debian ####
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||||
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||||
In Debian we need to add backports for Wheezy. To do that, please create a new file called "backports.list" in /etc/apt/sources.list.d, with the following content:
|
||||
|
||||
deb http://cdn.debian.net/debian wheezybackports main
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||||
|
||||
Refresh your repository data and install HAProxy.
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||||
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||||
# apt get update
|
||||
# apt get install haproxy
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||||
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||||
#### Install HAProxy on Ubuntu ####
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||||
|
||||
# apt get install haproxy
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||||
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||||
#### Install HAProxy on CentOS and RHEL ####
|
||||
|
||||
# yum install haproxy
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||||
|
||||
### Configure HAProxy ###
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||||
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||||
In this tutorial, we assume that there are two HTTP web servers up and running with IP addresses 192.168.100.2 and 192.168.100.3. We also assume that the load balancer will be configured at a server with IP address 192.168.100.4.
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|
||||
To make HAProxy functional, you need to change a number of items in /etc/haproxy/haproxy.cfg. These changes are described in this section. In case some configuration differs for different GNU/Linux distributions, it will be noted in the paragraph.
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||||
|
||||
#### 1. Configure Logging ####
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||||
|
||||
One of the first things you should do is to set up proper logging for your HAProxy, which will be useful for future debugging. Log configuration can be found in the global section of /etc/haproxy/haproxy.cfg. The following are distro-specific instructions for configuring logging for HAProxy.
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||||
|
||||
**CentOS or RHEL:**
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||||
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||||
To enable logging on CentOS/RHEL, replace:
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||||
|
||||
log 127.0.0.1 local2
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||||
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||||
with:
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||||
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||||
log 127.0.0.1 local0
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The next step is to set up separate log files for HAProxy in /var/log. For that, we need to modify our current rsyslog configuration. To make the configuration simple and clear, we will create a new file called haproxy.conf in /etc/rsyslog.d/ with the following content.
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||||
$ModLoad imudp
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||||
$UDPServerRun 514
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||||
$template Haproxy,"%msg%\n"
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||||
local0.=info /var/log/haproxy.log;Haproxy
|
||||
local0.notice /var/log/haproxystatus.log;Haproxy
|
||||
local0.* ~
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||||
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||||
This configuration will separate all HAProxy messages based on the $template to log files in /var/log. Now restart rsyslog to apply the changes.
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||||
|
||||
# service rsyslog restart
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||||
|
||||
**Debian or Ubuntu:**
|
||||
|
||||
To enable logging for HAProxy on Debian or Ubuntu, replace:
|
||||
|
||||
log /dev/log local0
|
||||
log /dev/log local1 notice
|
||||
|
||||
with:
|
||||
|
||||
log 127.0.0.1 local0
|
||||
|
||||
Next, to configure separate log files for HAProxy, edit a file called haproxy.conf (or 49-haproxy.conf in Debian) in /etc/rsyslog.d/ with the following content.
|
||||
|
||||
$ModLoad imudp
|
||||
$UDPServerRun 514
|
||||
$template Haproxy,"%msg%\n"
|
||||
local0.=info /var/log/haproxy.log;Haproxy
|
||||
local0.notice /var/log/haproxystatus.log;Haproxy
|
||||
local0.* ~
|
||||
|
||||
This configuration will separate all HAProxy messages based on the $template to log files in /var/log. Now restart rsyslog to apply the changes.
|
||||
|
||||
# service rsyslog restart
|
||||
|
||||
#### 2. Setting Defaults ####
|
||||
|
||||
The next step is to set default variables for HAProxy. Find the defaults section in /etc/haproxy/haproxy.cfg, and replace it with the following configuration.
|
||||
|
||||
defaults
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||||
log global
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||||
mode http
|
||||
option httplog
|
||||
option dontlognull
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||||
retries 3
|
||||
option redispatch
|
||||
maxconn 20000
|
||||
contimeout 5000
|
||||
clitimeout 50000
|
||||
srvtimeout 50000
|
||||
|
||||
The configuration stated above is recommended for HTTP load balancer use, but it may not be the optimal solution for your environment. In that case, feel free to explore HAProxy man pages to tweak it.
|
||||
|
||||
#### 3. Webfarm Configuration ####
|
||||
|
||||
Webfarm configuration defines the pool of available HTTP servers. Most of the settings for our load balancer will be placed here. Now we will create some basic configuration, where our nodes will be defined. Replace all of the configuration from frontend section until the end of file with the following code:
|
||||
|
||||
listen webfarm *:80
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||||
mode http
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||||
stats enable
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||||
stats uri /haproxy?stats
|
||||
stats realm Haproxy\ Statistics
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||||
stats auth haproxy:stats
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||||
balance roundrobin
|
||||
cookie LBN insert indirect nocache
|
||||
option httpclose
|
||||
option forwardfor
|
||||
server web01 192.168.100.2:80 cookie node1 check
|
||||
server web02 192.168.100.3:80 cookie node2 check
|
||||
|
||||
The line "listen webfarm *:80" defines on which interfaces our load balancer will listen. For the sake of the tutorial, I've set that to "*" which makes the load balancer listen on all our interfaces. In a real world scenario, this might be undesirable and should be replaced with an interface that is accessible from the internet.
|
||||
|
||||
stats enable
|
||||
stats uri /haproxy?stats
|
||||
stats realm Haproxy\ Statistics
|
||||
stats auth haproxy:stats
|
||||
|
||||
The above settings declare that our load balancer statistics can be accessed on http://<load-balancer-IP>/haproxy?stats. The access is secured with a simple HTTP authentication with login name "haproxy" and password "stats". These settings should be replaced with your own credentials. If you don't need to have these statistics available, then completely disable them.
|
||||
|
||||
Here is an example of HAProxy statistics.
|
||||
|
||||
|
||||
|
||||
The line "balance roundrobin" defines the type of load balancing we will use. In this tutorial we will use simple round robin algorithm, which is fully sufficient for HTTP load balancing. HAProxy also offers other types of load balancing:
|
||||
|
||||
- **leastconn**: gives connections to the server with the lowest number of connections.
|
||||
- **source**: hashes the source IP address, and divides it by the total weight of the running servers to decide which server will receive the request.
|
||||
- **uri**: the left part of the URI (before the question mark) is hashed and divided by the total weight of the running servers. The result determines which server will receive the request.
|
||||
- **url_param**: the URL parameter specified in the argument will be looked up in the query string of each HTTP GET request. You can basically lock the request using crafted URL to specific load balancer node.
|
||||
- **hdr(name**): the HTTP header <name> will be looked up in each HTTP request and directed to specific node.
|
||||
|
||||
The line "cookie LBN insert indirect nocache" makes our load balancer store persistent cookies, which allows us to pinpoint which node from the pool is used for a particular session. These node cookies will be stored with a defined name. In our case, I used "LBN", but you can specify any name you like. The node will store its string as a value for this cookie.
|
||||
|
||||
server web01 192.168.100.2:80 cookie node1 check
|
||||
server web02 192.168.100.3:80 cookie node2 check
|
||||
|
||||
The above part is the definition of our pool of web server nodes. Each server is represented with its internal name (e.g., web01, web02). IP address, and unique cookie string. The cookie string can be defined as anything you want. I am using simple node1, node2 ... node(n).
|
||||
|
||||
### Start HAProxy ###
|
||||
|
||||
When you are done with the configuration, it's time to start HAProxy and verify that everything is working as intended.
|
||||
|
||||
#### Start HAProxy on Centos/RHEL ####
|
||||
|
||||
Enable HAProxy to be started after boot and turn it on using:
|
||||
|
||||
# chkconfig haproxy on
|
||||
# service haproxy start
|
||||
|
||||
And of course don't forget to enable port 80 in the firewall as follows.
|
||||
|
||||
**Firewall on CentOS/RHEL 7:**
|
||||
|
||||
# firewallcmd permanent zone=public addport=80/tcp
|
||||
# firewallcmd reload
|
||||
|
||||
**Firewall on CentOS/RHEL 6:**
|
||||
|
||||
Add following line into section ":OUTPUT ACCEPT" of /etc/sysconfig/iptables:
|
||||
|
||||
A INPUT m state state NEW m tcp p tcp dport 80 j ACCEPT
|
||||
|
||||
and restart **iptables**:
|
||||
|
||||
# service iptables restart
|
||||
|
||||
#### Start HAProxy on Debian ####
|
||||
|
||||
#### Start HAProxy with: ####
|
||||
|
||||
# service haproxy start
|
||||
|
||||
Don't forget to enable port 80 in the firewall by adding the following line into /etc/iptables.up.rules:
|
||||
|
||||
A INPUT p tcp dport 80 j ACCEPT
|
||||
|
||||
#### Start HAProxy on Ubuntu ####
|
||||
|
||||
Enable HAProxy to be started after boot by setting "ENABLED" option to "1" in /etc/default/haproxy:
|
||||
|
||||
ENABLED=1
|
||||
|
||||
Start HAProxy:
|
||||
|
||||
# service haproxy start
|
||||
|
||||
and enable port 80 in the firewall:
|
||||
|
||||
# ufw allow 80
|
||||
|
||||
### Test HAProxy ###
|
||||
|
||||
To check whether HAproxy is working properly, we can do the following.
|
||||
|
||||
First, prepare test.php file with the following content:
|
||||
|
||||
<?php
|
||||
header('Content-Type: text/plain');
|
||||
echo "Server IP: ".$_SERVER['SERVER_ADDR'];
|
||||
echo "\nX-Forwarded-for: ".$_SERVER['HTTP_X_FORWARDED_FOR'];
|
||||
?>
|
||||
|
||||
This PHP file will tell us which server (i.e., load balancer) forwarded the request, and what backend web server actually handled the request.
|
||||
|
||||
Place this PHP file in the root directory of both backend web servers. Now use curl command to fetch this PHP file from the load balancer (192.168.100.4).
|
||||
|
||||
$ curl http://192.168.100.4/test.php
|
||||
|
||||
When we run this command multiple times, we should see the following two outputs alternate (due to the round robin algorithm).
|
||||
|
||||
Server IP: 192.168.100.2
|
||||
X-Forwarded-for: 192.168.100.4
|
||||
|
||||
----------
|
||||
|
||||
Server IP: 192.168.100.3
|
||||
X-Forwarded-for: 192.168.100.4
|
||||
|
||||
If we stop one of the two backend web servers, the curl command should still work, directing requests to the other available web server.
|
||||
|
||||
### Summary ###
|
||||
|
||||
By now you should have a fully operational load balancer that supplies your web nodes with requests in round robin mode. As always, feel free to experiment with the configuration to make it more suitable for your infrastructure. I hope this tutorial helped you to make your web projects more resistant and available.
|
||||
|
||||
As most of you already noticed, this tutorial contains settings for only one load balancer. Which means that we have just replaced one single point of failure with another. In real life scenarios you should deploy at least two or three load balancers to cover for any failures that might happen, but that is out of the scope of this tutorial right now.
|
||||
|
||||
If you have any questions or suggestions feel free to post them in the comments and I will do my best to answer or advice.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://xmodulo.com/haproxy-http-load-balancer-linux.html
|
||||
|
||||
作者：[Jaroslav Štěpánek][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://xmodulo.com/author/jaroslav
|
||||
[1]:http://www.haproxy.org/
|
||||
[2]:http://www.haproxy.org/10g.html
|
||||
[3]:http://xmodulo.com/how-to-install-lamp-server-on-ubuntu.html
|
||||
@ -1,301 +0,0 @@
|
||||
“ntpq -p” output
|
||||
================================================================================
|
||||
The [Gentoo][1] (and others?) [incomplete man pages for “ntpq -p”][2] merely give the description: “*Print a list of the peers known to the server as well as a summary of their state.*”
|
||||
|
||||
I had not seen this documented, hence here is a summary that can be used in addition to the brief version of the man page “[man ntpq][3]“. More complete details are given on: “[ntpq – standard NTP query program][4]” (source author), and [other examples of the man ntpq pages][5].
|
||||
|
||||
[NTP][6] is a protocol designed to synchronize the clocks of computers over a ([WAN][7] or [LAN][8]) [udp][9] network. From [Wikipedia – NTP][10]:
|
||||
|
||||
> The Network Time Protocol (NTP) is a protocol and software implementation for synchronizing the clocks of computer systems over packet-switched, variable-latency data networks. Originally designed by David L. Mills of the University of Delaware and still maintained by him and a team of volunteers, it was first used before 1985 and is one of the oldest Internet protocols.
|
||||
|
||||
For an awful lot more than you might ever want to know about time and NTP, see “[The NTP FAQ, Time, what Time?][11]” and the current [RFCs for NTP][12]. The earlier “Network Time Protocol (Version 3) RFC” ([txt][13], or [pdf][14], Appendix E, The NTP Timescale and its Chronometry, p70) includes an interesting explanation of the changes in, and relations between, our timekeeping systems over the past 5000 years or so. Wikipedia gives a broader view in the articles [Time][15] and [Calendar][16].
|
||||
|
||||
The command “ntpq -p” outputs a table such as for example:
|
||||
|
||||
remote refid st t when poll reach delay offset jitter
|
||||
==============================================================================
|
||||
LOCAL(0) .LOCL. 10 l 96h 64 0 0.000 0.000 0.000
|
||||
*ns2.example.com 10.193.2.20 2 u 936 1024 377 31.234 3.353 3.096
|
||||
|
||||
### Further detail: ###
|
||||
|
||||
#### Table headings: ####
|
||||
|
||||
|
||||
- **remote** – The remote peer or server being synced to. “LOCAL” is this local host (included in case there are no remote peers or servers available);
|
||||
- **refid** – Where or what the remote peer or server is itself synchronised to;
|
||||
- **st** – The remote peer or server [Stratum][17]
|
||||
- **t** – Type (u: [unicast][18] or [manycast][19] client, b: [broadcast][20] or [multicast][21] client, l: local reference clock, s: symmetric peer, A: manycast server, B: broadcast server, M: multicast server, see “[Automatic Server Discovery][22]“);
|
||||
- **when** – When last polled (seconds ago, “h” hours ago, or “d” days ago);
|
||||
- **poll** – Polling frequency: [rfc5905][23] suggests this ranges in NTPv4 from 4 (16s) to 17 (36h) (log2 seconds), however observation suggests the actual displayed value is seconds for a much smaller range of 64 (26) to 1024 (210) seconds;
|
||||
- **reach** – An 8-bit left-shift shift register value recording polls (bit set = successful, bit reset = fail) displayed in [octal][24];
|
||||
- **delay** – Round trip communication delay to the remote peer or server (milliseconds);
|
||||
- **offset** – Mean offset (phase) in the times reported between this local host and the remote peer or server ([RMS][25], milliseconds);
|
||||
- **jitter** – Mean deviation (jitter) in the time reported for that remote peer or server (RMS of difference of multiple time samples, milliseconds);
|
||||
|
||||
#### Select Field tally code: ####
|
||||
|
||||
The first character displayed in the table (Select Field tally code) is a state flag (see [Peer Status Word][26]) that follows the sequence ” “, “x”, “-“, “#”, “+”, “*”, “o”:
|
||||
|
||||
|
||||
- ”** **” – No state indicated for:
|
||||
- non-communicating remote machines,
|
||||
- “LOCAL” for this local host,
|
||||
- (unutilised) high stratum servers,
|
||||
- remote machines that are themselves using this host as their synchronisation reference;
|
||||
- “**x**” – Out of tolerance, do not use (discarded by intersection algorithm);
|
||||
- “**-**” – Out of tolerance, do not use (discarded by the cluster algorithm);
|
||||
- “**#**” – Good remote peer or server but not utilised (not among the first six peers sorted by synchronization distance, ready as a backup source);
|
||||
- “**+**” – Good and a preferred remote peer or server (included by the combine algorithm);
|
||||
- “*****” – The remote peer or server presently used as the primary reference;
|
||||
- “**o**” – PPS peer (when the prefer peer is valid). The actual system synchronization is derived from a pulse-per-second (PPS) signal, either indirectly via the PPS reference clock driver or directly via kernel interface.
|
||||
|
||||
See the [Clock Select Algorithm][27].
|
||||
|
||||
#### “refid”: ####
|
||||
|
||||
The **refid** can have the status values:
|
||||
|
||||
|
||||
- An IP address – The [IP address][28] of a remote peer or server;
|
||||
- **.LOCL.** – This local host (a place marker at the lowest stratum included in case there are no remote peers or servers available);
|
||||
- **.PPS.** – “[Pulse Per Second][29]” from a time standard;
|
||||
- **.IRIG.** – [Inter-Range Instrumentation Group][30] time code;
|
||||
- **.ACTS.** – American [NIST time standard][31] telephone modem;
|
||||
- **.NIST.** – American NIST time standard telephone modem;
|
||||
- **.PTB.** – German [PTB][32] time standard telephone modem;
|
||||
- **.USNO.** – American [USNO time standard][33] telephone modem;
|
||||
- **.CHU.** – [CHU][34] ([HF][35], Ottawa, ON, Canada) time standard radio receiver;
|
||||
- **.DCFa.** – [DCF77][36] ([LF][37], Mainflingen, Germany) time standard radio receiver;
|
||||
- **.HBG.** – [HBG][38] (LF Prangins, Switzerland) time standard radio receiver;
|
||||
- **.JJY.** – [JJY][39] (LF Fukushima, Japan) time standard radio receiver;
|
||||
- **.LORC.** – [LORAN][40]-C station ([MF][41]) time standard radio receiver. Note, [no longer operational][42] (superseded by [eLORAN][43]);
|
||||
- **.MSF.** – [MSF][44] (LF, Anthorn, Great Britain) time standard radio receiver;
|
||||
- **.TDF.** – [TDF][45] (MF, Allouis, France) time standard radio receiver;
|
||||
- **.WWV.** – [WWV][46] (HF, Ft. Collins, CO, America) time standard radio receiver;
|
||||
- **.WWVB.** – [WWVB][47] (LF, Ft. Collins, CO, America) time standard radio receiver;
|
||||
- **.WWVH.** – [WWVH][48] (HF, Kauai, HI, America) time standard radio receiver;
|
||||
- **.GOES.** – American [Geosynchronous Orbit Environment Satellite][49];
|
||||
- **.GPS.** – American [GPS][50];
|
||||
- **.GAL.** – [Galileo][51] European [GNSS][52];
|
||||
- **.ACST.** – manycast server;
|
||||
- **.AUTH.** – authentication error;
|
||||
- **.AUTO.** – Autokey sequence error;
|
||||
- **.BCST.** – broadcast server;
|
||||
- **.CRYPT.** – Autokey protocol error;
|
||||
- **.DENY.** – access denied by server;
|
||||
- **.INIT.** – association initialized;
|
||||
- **.MCST.** – multicast server;
|
||||
- **.RATE.** – (polling) rate exceeded;
|
||||
- **.TIME.** – association timeout;
|
||||
- **.STEP.** – step time change, the offset is less than the panic threshold (1000ms) but greater than the step threshold (125ms).
|
||||
|
||||
#### Operation notes ####
|
||||
|
||||
A time server will report time information with no time updates from clients (unidirectional updates), whereas a peer can update fellow participating peers to converge upon a mutually agreed time (bidirectional updates).
|
||||
|
||||
During [initial startup][53]:
|
||||
|
||||
> Unless using the iburst option, the client normally takes a few minutes to synchronize to a server. If the client time at startup happens to be more than 1000s distant from NTP time, the daemon exits with a message to the system log directing the operator to manually set the time within 1000s and restart. If the time is less than 1000s but more than 128s distant, a step correction occurs and the daemon restarts automatically.
|
||||
|
||||
> When started for the first time and a frequency file is not present, the daemon enters a special mode in order to calibrate the frequency. This takes 900s during which the time is not [disciplined][54]. When calibration is complete, the daemon creates the frequency file and enters normal mode to amortize whatever residual offset remains.
|
||||
|
||||
Stratum 0 devices are such as atomic (caesium, rubidium) clocks, GPS clocks, or other time standard radio clocks providing a time signal to the Stratum 1 time servers. NTP reports [UTC][55] (Coordinated Universal Time) only. Client programs/utilities then use [time zone][56] data to report local time from the synchronised UTC.
|
||||
|
||||
The protocol is highly accurate, using a resolution of less than a nanosecond (about 2-32 seconds). The time resolution achieved and other parameters for a host (host hardware and operating system limited) is reported by the command “ntpq -c rl” (see [rfc1305][57] Common Variables and [rfc5905][58]).
|
||||
|
||||
#### “ntpq -c rl” output parameters: ####
|
||||
|
||||
- **precision** is rounded to give the next larger integer power of two. The achieved resolution is thus 2precision (seconds)
|
||||
- **rootdelay** – total roundtrip delay to the primary reference source at the root of the synchronization subnet. Note that this variable can take on both positive and negative values, depending on clock precision and skew (seconds)
|
||||
- **rootdisp** – maximum error relative to the primary reference source at the root of the synchronization subnet (seconds)
|
||||
- **tc** – NTP algorithm [PLL][59] (phase locked loop) or [FLL][60] (frequency locked loop) time constant (log2)
|
||||
- **mintc** – NTP algorithm PLL/FLL minimum time constant or ‘fastest response’ (log2)
|
||||
- **offset** – best and final offset determined by the combine algorithm used to discipline the system clock (ms)
|
||||
- **frequency** – system clock period (log2 seconds)
|
||||
- **sys_jitter** – best and final jitter determined by the combine algorithm used to discipline the system clock (ms)
|
||||
- **clk_jitter** – host hardware(?) system clock jitter (ms)
|
||||
- **clk_wander** – host hardware(?) system clock wander ([PPM][61] – parts per million)
|
||||
|
||||
Jitter (also called timing jitter) refers to short-term variations in frequency with components greater than 10Hz, while wander refers to long-term variations in frequency with components less than 10Hz. (Stability refers to the systematic variation of frequency with time and is synonymous with aging, drift, trends, etc.)
|
||||
|
||||
#### Operation notes (continued) ####
|
||||
|
||||
The NTP software maintains a continuously updated drift correction. For a correctly configured and stable system, a reasonable expectation for modern hardware synchronising over an uncongested internet connection is for network client devices to be synchronised to within a few milliseconds of UTC at the time of synchronising to the NTP service. (What accuracy can be expected between peers on an uncongested Gigabit LAN?)
|
||||
|
||||
Note that for UTC, a [leap second][62] can be inserted into the reported time up to twice a year to allow for variations in the Earth’s rotation. Also beware of the one hour time shifts for when local times are reported for “[daylight savings][63]” times. Also, the clock for a client device will run independently of UTC until resynchronised oncemore, unless that device is calibrated or a drift correction is applied.
|
||||
|
||||
#### [What happens during a Leap Second?][64] ####
|
||||
|
||||
> During a leap second, either one second is removed from the current day, or a second is added. In both cases this happens at the end of the UTC day. If a leap second is inserted, the time in UTC is specified as 23:59:60. In other words, it takes two seconds from 23:59:59 to 0:00:00 instead of one. If a leap second is deleted, time will jump from 23:59:58 to 0:00:00 in one second instead of two. See also [The Kernel Discipline][65].
|
||||
|
||||
So… What actually is the value for the step threshold: 125ms or 128ms? And what are the PLL/FLL tc units (log2 s? ms?)? And what accuracy can be expected between peers on an uncongested Gigabit LAN?
|
||||
|
||||
|
||||
|
||||
Thanks for comments from Camilo M and Chris B. Corrections and further details welcomed.
|
||||
|
||||
Cheers,
|
||||
Martin
|
||||
|
||||
### Apocrypha: ###
|
||||
|
||||
- The [epoch for NTP][66] starts in year 1900 while the epoch in UNIX starts in 1970.
|
||||
- [Time corrections][67] are applied gradually, so it may take up to three hours until the frequency error is compensated.
|
||||
- [Peerstats and loopstats][68] can be logged to [summarise/plot time offsets and errors][69]
|
||||
- [RMS][70] – Root Mean Square
|
||||
- [PLL][71] – Phase locked loop
|
||||
- [FLL][72] – Frequency locked loop
|
||||
- [PPM][73] – Parts per million, used here to describe rate of time drift
|
||||
- [man ntpq (Gentoo brief version)][74]
|
||||
- [man ntpq (long version)][75]
|
||||
- [man ntpq (Gentoo long version)][76]
|
||||
|
||||
### See: ###
|
||||
|
||||
- [ntpq – standard NTP query program][77]
|
||||
- [The Network Time Protocol (NTP) Distribution][78]
|
||||
- A very brief [history][79] of NTP
|
||||
- A more detailed brief history: “Mills, D.L., A brief history of NTP time: confessions of an Internet timekeeper. Submitted for publication; please do not cite or redistribute” ([pdf][80])
|
||||
- [NTP RFC][81] standards documents
|
||||
- Network Time Protocol (Version 3) RFC – [txt][82], or [pdf][83]. Appendix E, The NTP Timescale and its Chronometry, p70, includes an interesting explanation of the changes in, and relations between, our timekeeping systems over the past 5000 years or so
|
||||
- Wikipedia: [Time][84] and [Calendar][85]
|
||||
- [John Harrison and the Longitude problem][86]
|
||||
- [Clock of the Long Now][87] – The 10,000 Year Clock
|
||||
- John C Taylor – [Chronophage][88]
|
||||
- [Orders of magnitude of time][89]
|
||||
- The [Greenwich Time Signal][90]
|
||||
|
||||
### Others: ###
|
||||
|
||||
SNTP (Simple Network Time Protocol, [RFC 4330][91]) is basically also NTP, but lacks some internal algorithms for servers where the ultimate performance of a full NTP implementation based on [RFC 1305][92] is neither needed nor justified.
|
||||
|
||||
The W32Time [Windows Time Service][93] is a non-standard implementation of SNTP, with no accuracy guarantees, and an assumed accuracy of no better than about a 1 to 2 second range. (Is that due to there being no system clock drift correction and a time update applied only once every 24 hours assumed for a [PC][94] with typical clock drift?)
|
||||
|
||||
There is also the [PTP (IEEE 1588)][95] Precision Time Protocol. See Wikipedia: [Precision Time Protocol][96]. A software demon is [PTPd][97]. The significant features are that it is intended as a [LAN][98] high precision master-slave synchronisation system synchronising at the microsecond scale to a master clock for [International Atomic Time][99] (TAI, [monotonic][100], no leap seconds). Data packet timestamping can be appended by hardware at the physical layer by a network interface card or switch for example. Network kit supporting PTP can timestamp data packets in and out in a way that removes the delay effect of processing within the switch/router. You can run PTP without hardware timestamping but it might not synchronise if the time errors introduced are too great. Also it will struggle to work through a router (large delays) for the same reason.
|
||||
|
||||
### Older time synchronization protocols: ###
|
||||
|
||||
- DTSS – Digital Time Synchronisation Service by Digital Equipment Corporation, superseded by NTP. See an example of [DTSS VMS C code c2000][101]. (Any DTSS articles/documentation anywhere?)
|
||||
- [DAYTIME protocol][102], synchronization protocol using [TCP][103] or [UDP][104] port 13
|
||||
- [ICMP Timestamp][105] and [ICMP Timestamp Reply][106], synchronization protocol using [ICMP][107]
|
||||
- [Time Protocol][108], synchronization protocol using TCP or UDP port 37
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://nlug.ml1.co.uk/2012/01/ntpq-p-output/831
|
||||
|
||||
作者：Martin L
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
|
||||
|
||||
[1]:http://www.gentoo.org/
|
||||
[2]:http://nlug.ml1.co.uk/2012/01/man-ntpq-gentoo-brief-version/853
|
||||
[3]:http://www.thelinuxblog.com/linux-man-pages/1/ntpq
|
||||
[4]:http://www.eecis.udel.edu/~mills/ntp/html/ntpq.html
|
||||
[5]:http://linux.die.net/man/8/ntpq
|
||||
[6]:http://www.ntp.org/
|
||||
[7]:http://en.wikipedia.org/wiki/Wide_area_network
|
||||
[8]:http://en.wikipedia.org/wiki/Local_area_network
|
||||
[9]:http://en.wikipedia.org/wiki/User_Datagram_Protocol
|
||||
[10]:http://en.wikipedia.org/wiki/Network_Time_Protocol
|
||||
[11]:http://www.ntp.org/ntpfaq/NTP-s-time.htm
|
||||
[12]:http://www.ntp.org/rfc.html
|
||||
[13]:http://www.ietf.org/rfc/rfc1305.txt
|
||||
[14]:http://www.rfc-editor.org/rfc/rfc1305.pdf
|
||||
[15]:http://en.wikipedia.org/wiki/Time
|
||||
[16]:http://en.wikipedia.org/wiki/Calendar
|
||||
[17]:http://en.wikipedia.org/wiki/Network_Time_Protocol#Clock_strata
|
||||
[18]:http://en.wikipedia.org/wiki/Unicast
|
||||
[19]:http://www.eecis.udel.edu/~mills/ntp/html/manyopt.html#mcst
|
||||
[20]:http://en.wikipedia.org/wiki/Broadcasting_%28computing%29
|
||||
[21]:http://en.wikipedia.org/wiki/Multicast
|
||||
[22]:http://www.eecis.udel.edu/~mills/ntp/html/manyopt.html
|
||||
[23]:http://www.ietf.org/rfc/rfc5905.txt
|
||||
[24]:http://en.wikipedia.org/wiki/Octal#In_computers
|
||||
[25]:http://en.wikipedia.org/wiki/Root_mean_square
|
||||
[26]:http://www.eecis.udel.edu/~mills/ntp/html/decode.html#peer
|
||||
[27]:http://www.eecis.udel.edu/~mills/ntp/html/select.html
|
||||
[28]:http://en.wikipedia.org/wiki/Ip_address
|
||||
[29]:http://en.wikipedia.org/wiki/Pulse_per_second
|
||||
[30]:http://en.wikipedia.org/wiki/Inter-Range_Instrumentation_Group
|
||||
[31]:http://en.wikipedia.org/wiki/Standard_time_and_frequency_signal_service
|
||||
[32]:http://www.ptb.de/index_en.html
|
||||
[33]:http://en.wikipedia.org/wiki/United_States_Naval_Observatory#Time_service
|
||||
[34]:http://en.wikipedia.org/wiki/CHU_%28radio_station%29
|
||||
[35]:http://en.wikipedia.org/wiki/High_frequency
|
||||
[36]:http://en.wikipedia.org/wiki/DCF77
|
||||
[37]:http://en.wikipedia.org/wiki/Low_frequency
|
||||
[38]:http://en.wikipedia.org/wiki/HBG_%28time_signal%29
|
||||
[39]:http://en.wikipedia.org/wiki/JJY#Time_standards
|
||||
[40]:http://en.wikipedia.org/wiki/LORAN#Timing_and_synchronization
|
||||
[41]:http://en.wikipedia.org/wiki/Medium_frequency
|
||||
[42]:http://en.wikipedia.org/wiki/LORAN#The_future_of_LORAN
|
||||
[43]:http://en.wikipedia.org/wiki/LORAN#eLORAN
|
||||
[44]:http://en.wikipedia.org/wiki/Time_from_NPL#The_.27MSF_signal.27_and_the_.27Rugby_clock.27
|
||||
[45]:http://en.wikipedia.org/wiki/T%C3%A9l%C3%A9_Distribution_Fran%C3%A7aise
|
||||
[46]:http://en.wikipedia.org/wiki/WWV_%28radio_station%29#Time_signals
|
||||
[47]:http://en.wikipedia.org/wiki/WWVB
|
||||
[48]:http://en.wikipedia.org/wiki/WWVH
|
||||
[49]:http://en.wikipedia.org/wiki/GOES#Further_reading
|
||||
[50]:http://en.wikipedia.org/wiki/Gps#Timekeeping
|
||||
[51]:http://en.wikipedia.org/wiki/Galileo_%28satellite_navigation%29#The_concept
|
||||
[52]:http://en.wikipedia.org/wiki/Gnss
|
||||
[53]:http://www.eecis.udel.edu/~mills/ntp/html/debug.html
|
||||
[54]:http://www.ntp.org/ntpfaq/NTP-s-algo-kernel.htm
|
||||
[55]:http://en.wikipedia.org/wiki/Coordinated_Universal_Time
|
||||
[56]:http://en.wikipedia.org/wiki/Time_zone
|
||||
[57]:http://www.ietf.org/rfc/rfc1305.txt
|
||||
[58]:http://www.ietf.org/rfc/rfc5905.txt
|
||||
[59]:http://en.wikipedia.org/wiki/PLL
|
||||
[60]:http://en.wikipedia.org/wiki/Frequency-locked_loop
|
||||
[61]:http://en.wikipedia.org/wiki/Parts_per_million
|
||||
[62]:http://en.wikipedia.org/wiki/Leap_second
|
||||
[63]:http://en.wikipedia.org/wiki/Daylight_saving_time
|
||||
[64]:http://www.ntp.org/ntpfaq/NTP-s-time.htm#Q-TIME-LEAP-SECOND
|
||||
[65]:http://www.ntp.org/ntpfaq/NTP-s-algo-kernel.htm
|
||||
[66]:http://www.ntp.org/ntpfaq/NTP-s-algo.htm#AEN1895
|
||||
[67]:http://www.ntp.org/ntpfaq/NTP-s-algo.htm#Q-ACCURATE-CLOCK
|
||||
[68]:http://www.ntp.org/ntpfaq/NTP-s-trouble.htm#Q-TRB-MON-STATFIL
|
||||
[69]:http://www.ntp.org/ntpfaq/NTP-s-trouble.htm#AEN5086
|
||||
[70]:http://en.wikipedia.org/wiki/Root_mean_square
|
||||
[71]:http://en.wikipedia.org/wiki/PLL
|
||||
[72]:http://en.wikipedia.org/wiki/Frequency-locked_loop
|
||||
[73]:http://en.wikipedia.org/wiki/Parts_per_million
|
||||
[74]:http://nlug.ml1.co.uk/2012/01/man-ntpq-gentoo-brief-version/853
|
||||
[75]:http://nlug.ml1.co.uk/2012/01/man-ntpq-long-version/855
|
||||
[76]:http://nlug.ml1.co.uk/2012/01/man-ntpq-gentoo-long-version/856
|
||||
[77]:http://www.eecis.udel.edu/~mills/ntp/html/ntpq.html
|
||||
[78]:http://www.eecis.udel.edu/~mills/ntp/html/index.html
|
||||
[79]:http://www.ntp.org/ntpfaq/NTP-s-def-hist.htm
|
||||
[80]:http://www.eecis.udel.edu/~mills/database/papers/history.pdf
|
||||
[81]:http://www.ntp.org/rfc.html
|
||||
[82]:http://www.ietf.org/rfc/rfc1305.txt
|
||||
[83]:http://www.rfc-editor.org/rfc/rfc1305.pdf
|
||||
[84]:http://en.wikipedia.org/wiki/Time
|
||||
[85]:http://en.wikipedia.org/wiki/Calendar
|
||||
[86]:http://www.rmg.co.uk/harrison
|
||||
[87]:http://longnow.org/clock/
|
||||
[88]:http://johnctaylor.com/
|
||||
[89]:http://en.wikipedia.org/wiki/Orders_of_magnitude_%28time%29
|
||||
[90]:http://en.wikipedia.org/wiki/Greenwich_Time_Signal
|
||||
[91]:http://tools.ietf.org/html/rfc4330
|
||||
[92]:http://tools.ietf.org/html/rfc1305
|
||||
[93]:http://en.wikipedia.org/wiki/Network_Time_Protocol#Microsoft_Windows
|
||||
[94]:http://en.wikipedia.org/wiki/Personal_computer
|
||||
[95]:http://www.nist.gov/el/isd/ieee/ieee1588.cfm
|
||||
[96]:http://en.wikipedia.org/wiki/IEEE_1588
|
||||
[97]:http://ptpd.sourceforge.net/
|
||||
[98]:http://en.wikipedia.org/wiki/Local_area_network
|
||||
[99]:http://en.wikipedia.org/wiki/International_Atomic_Time
|
||||
[100]:http://en.wikipedia.org/wiki/Monotonic_function
|
||||
[101]:http://antinode.info/ftp/dtss_ntp/
|
||||
[102]:http://en.wikipedia.org/wiki/DAYTIME
|
||||
[103]:http://en.wikipedia.org/wiki/Transmission_Control_Protocol
|
||||
[104]:http://en.wikipedia.org/wiki/User_Datagram_Protocol
|
||||
[105]:http://en.wikipedia.org/wiki/ICMP_Timestamp
|
||||
[106]:http://en.wikipedia.org/wiki/ICMP_Timestamp_Reply
|
||||
[107]:http://en.wikipedia.org/wiki/Internet_Control_Message_Protocol
|
||||
[108]:http://en.wikipedia.org/wiki/Time_Protocol
|
||||
@ -1,77 +0,0 @@
|
||||
SPccman...................
|
||||
Quick systemd-nspawn guide
|
||||
================================================================================
|
||||
I switched to using systemd-nspawn in place of chroot and wanted to give a quick guide to using it. The short version is that I’d strongly recommend that anybody running systemd that uses chroot switch over - there really are no downsides as long as your kernel is properly configured.
|
||||
|
||||
Chroot should be no stranger to anybody who works on distros, and I suspect that the majority of Gentoo users have need for it from time to time.
|
||||
|
||||
### The Challenges of chroot ###
|
||||
|
||||
For most interactive uses it isn’t sufficient to just run chroot. Usually you need to mount /proc, /sys, and bind mount /dev so that you don’t have issues like missing ptys, etc. If you use tmpfs you might also want to mount the new tmp, var/tmp as tmpfs. Then you might want to make other bind mounts into the chroot. None of this is particularly difficult, but you usually end up writing a small script to manage it.
|
||||
|
||||
Now, I routinely do full backups, and usually that involves excluding stuff like tmp dirs, and anything resembling a bind mount. When I set up a new chroot that means updating my backup config, which I usually forget to do since most of the time the chroot mounts aren’t running anyway. Then when I do leave it mounted overnight I end up with backups consuming lots of extra space (bind mounts of large trees).
|
||||
|
||||
Finally, systemd now by default handles bind mounts a little differently when they contain other mount points (such as when using -rbind). Apparently unmounting something in the bind mount will cause systemd to unmount the corresponding directory on the other side of the bind. Imagine my surprise when I unmounted my chroot bind to /dev and discovered /dev/pts and /dev/shm no longer mounted on the host. It looks like there are ways to change that, but this isn’t the point of my post (it just spurred me to find another way).
|
||||
|
||||
### Systemd-nspawn’s Advantages ###
|
||||
|
||||
Systemd-nspawn is a tool that launches a container, and it can operate just like chroot in its simplest form. By default it automatically sets up most of the overhead like /dev, /tmp, etc. With a few options it can also set up other bind mounts as well. When the container exits all the mounts are cleaned up.
|
||||
|
||||
From the outside of the container nothing appears different when the container is running. In fact, you could spawn 5 different systemd-nspawn container instances from the same chroot and they wouldn’t have any interaction except via the filesystem (and that excludes /dev, /tmp, and so on - only changes in /usr, /etc will propagate across). Your backup won’t see the bind mounts, or tmpfs, or anything else mounted within the container.
|
||||
|
||||
The container also has all those other nifty container benefits like containment - a killall inside the container won’t touch anything outside, and so on. The security isn’t airtight - the intent is to prevent accidental mistakes.
|
||||
|
||||
Then, if you use a compatible sysvinit (which includes systemd, and I think recent versions of openrc), you can actually boot the container, which drops you to a getty inside. That means you can use fstab to do additional mounts inside the container, run daemons, and so on. You get almost all the benefits of virtualization for the cost of a chroot (no need to build a kernel, and so on). It is a bit odd to be running systemctl poweroff inside what looks just like a chroot, but it works.
|
||||
|
||||
Note that unless you do a bit more setup you will share the same network interface with the host, so no running sshd on the container if you have it on the host, etc. I won’t get into this but it shouldn’t be hard to run a separate network namespace and bind the interfaces so that the new instance can run dhcp.
|
||||
|
||||
### How to do it ###
|
||||
|
||||
So, getting it actually working will likely be the shortest bit in this post.
|
||||
|
||||
You need support for namespaces and multiple devpts instances in your kernel:
|
||||
|
||||
CONFIG_UTS_NS=y
|
||||
CONFIG_IPC_NS=y
|
||||
CONFIG_USER_NS=y
|
||||
CONFIG_PID_NS=y
|
||||
CONFIG_NET_NS=y
|
||||
CONFIG_DEVPTS_MULTIPLE_INSTANCES=y
|
||||
|
||||
From there launching a namespace just like a chroot is really simple:
|
||||
|
||||
systemd-nspawn -D .
|
||||
|
||||
That’s it - you can exit from it just like a chroot. From inside you can run mount and see that it has taken care of /dev and /tmp for you. The “.” is the path to the chroot, which I assume is the current directory. With nothing further it runs bash inside.
|
||||
|
||||
If you want to add some bind mounts it is easy:
|
||||
|
||||
systemd-nspawn -D . --bind /usr/portage
|
||||
|
||||
Now your /usr/portage is bound to your host, so no need to sync/etc. If you want to bind to a different destination add a “:dest” after the source, relative to the root of the chroot (so --bind foo is the same as --bind foo:foo).
|
||||
|
||||
If the container has a functional init that can handle being run inside, you can add a -b to boot it:
|
||||
|
||||
systemd-nspawn -D . --bind /usr/portage -b
|
||||
|
||||
Watch the init do its job. Shut down the container to exit.
|
||||
|
||||
Now, if that container is running systemd you can direct its journal to the host journal with -h:
|
||||
|
||||
systemd-nspawn -D . --bind /usr/portage -j -b
|
||||
|
||||
Now, nspawn registers the container so that it shows up in machinectl. That makes it easy to launch a new getty on it, or ssh to it (if it is running ssh - see my note above about network namespaces), or power it off from the host.
|
||||
|
||||
That’s it. If you’re running systemd I’d suggest ditching chroot almost entirely in favor of nspawn.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://rich0gentoo.wordpress.com/2014/07/14/quick-systemd-nspawn-guide/
|
||||
|
||||
作者：[rich0][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://rich0gentoo.wordpress.com/
|
||||
@ -0,0 +1,48 @@
|
||||
Vic020
|
||||
|
||||
How To Install Kodi 14 (XBMC) In Ubuntu 14.04 & Linux Mint 17
|
||||
================================================================================
|
||||
|
||||
|
||||
[Kodi][1], formerly and popularly known as XBMC, has [released its latest version 14][2] which is code named Helix. It is fairly easy to **install Kodi 14 in Ubuntu 14.04** thanks to the official PPA provided by XBMC.
|
||||
|
||||
For those who do not know already, Kodi is a media center application available for all major platforms like Windows, Linux, Mac, Android etc. It turns your device in to a full screen media center where you can manage all your music and videos, either on local or on network drive, watch You Tube, [Netflix][3], Hulu, Amazon Prime and other streaming services.
|
||||
|
||||
### Install XBMC 14 Kodi Helix in Ubuntu 14.04, 14.10 and Linux Mint 17 ###
|
||||
|
||||
Thanks to the official PPA, you can easily install Kodi 14 in Ubuntu 14.04, Ubuntu 12.04, Linux Mint 17, Pinguy OS 14.04, Deepin 2014, LXLE 14.04, Linux Lite 2.0, Elementary OS and other Ubuntu based Linux distributions. Open a terminal (Ctrl+Alt+T) and use the following commands:
|
||||
|
||||
sudo add-apt-repository ppa:team-xbmc/ppa
|
||||
sudo apt-get update
|
||||
sudo apt-get install kodi
|
||||
|
||||
The download size would be around 100 MB, which is not huge in my opinion. To install some encode addons, use the command below:
|
||||
|
||||
sudo apt-get install kodi-audioencoder-* kodi-pvr-*
|
||||
|
||||
#### Remove Kodi 14 from Ubuntu ####
|
||||
|
||||
To uninstall Kodi 14 from your system, use the command below:
|
||||
|
||||
sudo apt-get remove kodi
|
||||
|
||||
You should also remove the PPA from the software sources:
|
||||
|
||||
sudo add-apt-repository --remove ppa:team-xbmc/ppa
|
||||
|
||||
I hope this quick post helped you to install Kodi 14 in Ubuntu, Linux Mint and other Linux. How do you find Kodi 14 Helix? Do you use some other media center as an alternative to XBMC? Do share your views in the comment section.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://itsfoss.com/install-kodi-14-xbmc-in-ubuntu-14-04-linux-mint-17/
|
||||
|
||||
作者：[Abhishek][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://itsfoss.com/author/Abhishek/
|
||||
[1]:http://kodi.tv/
|
||||
[2]:http://kodi.tv/kodi-14-0-helix-unwinds/
|
||||
[3]:http://itsfoss.com/watch-netflix-in-ubuntu-14-04/
|
||||
@ -0,0 +1,47 @@
|
||||
How To Install Winusb In Ubuntu 14.04
|
||||
================================================================================
|
||||
|
||||
|
||||
[WinUSB][1] is a simple and useful tool that lets you create USB stick Windows installer from the Windows ISO image or DVD. It comprises of both GUI and command line tool and you can decide to choose which to use based on your preference.
|
||||
|
||||
In this quick post we shall see **how to install WinUSB in Ubuntu 14.04, 14.10 and Linux Mint 17**.
|
||||
|
||||
### Install WinUSB in Ubuntu 14.04 and Ubuntu 14.10 ###
|
||||
|
||||
Until Ubuntu 13.10, WinUSB was developed actively and it was available for installation via its official PPA. This PPA has not been updated for Ubuntu 14.04 Trusty Tahr and 14.10 but the binaries are still there and works fine in newer version of Ubuntu and Linux Mint. Based on [whether your Ubuntu system is 32 bit or 64 bit][2], use the command below to download the binaries:
|
||||
|
||||
Open a terminal and use the following command for 32 bit system:
|
||||
|
||||
wget https://launchpad.net/~colingille/+archive/freshlight/+files/winusb_1.0.11+saucy1_i386.deb
|
||||
|
||||
For 64 bit systems, use the command below:
|
||||
|
||||
wget https://launchpad.net/~colingille/+archive/freshlight/+files/winusb_1.0.11+saucy1_amd64.deb
|
||||
|
||||
Once you have downloaded the correct binaries, you can install WinUSB using the command below:
|
||||
|
||||
sudo dpkg -i winusb*
|
||||
|
||||
Don’t worry if you see error when you try to install WinUSB. Fix the dependency errors with this command:
|
||||
|
||||
sudo apt-get -f install
|
||||
|
||||
Afterwards, you can search for WinUSB in Unity Dash and use it to create a live USB of Windows in Ubuntu 14.04.
|
||||
|
||||
|
||||
|
||||
I hope this quick post helped you to **install WinUSB in Ubuntu 14.04, 14.10 and Linux Mint 17**.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://itsfoss.com/install-winusb-in-ubuntu-14-04/
|
||||
|
||||
作者：[Abhishek][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://itsfoss.com/author/Abhishek/
|
||||
[1]:http://en.congelli.eu/prog_info_winusb.html
|
||||
[2]:http://itsfoss.com/how-to-know-ubuntu-unity-version/
|
||||
@ -0,0 +1,189 @@
|
||||
Ubuntu apt-get & apt-cache commands with practical examples
|
||||
================================================================================
|
||||
Apt-get & apt-cache are the command line **package management** utility in **Ubuntu Linux**. GUI version of apt-get command is the Synaptic Package Manager, in this post we are going to discuss 15 different examples of apt-get & apt-cache commands.
|
||||
|
||||
### Example:1 List of all the available packages ###
|
||||
|
||||
linuxtechi@localhost:~$ apt-cache pkgnames
|
||||
account-plugin-yahoojp
|
||||
ceph-fuse
|
||||
dvd+rw-tools
|
||||
e3
|
||||
gnome-commander-data
|
||||
grub-gfxpayload-lists
|
||||
gweled
|
||||
.......................................
|
||||
|
||||
### Example:2 Search Packages using keywords ###
|
||||
|
||||
This command is very helpful when you are not sure about package name , just enter the keyword and apt-get command will list packages related to the keyword.
|
||||
|
||||
linuxtechi@localhost:~$ apt-cache search "web server"
|
||||
apache2 - Apache HTTP Server
|
||||
apache2-bin - Apache HTTP Server (binary files and modules)
|
||||
apache2-data - Apache HTTP Server (common files)
|
||||
apache2-dbg - Apache debugging symbols
|
||||
apache2-dev - Apache HTTP Server (development headers)
|
||||
apache2-doc - Apache HTTP Server (on-site documentation)
|
||||
apache2-utils - Apache HTTP Server (utility programs for web servers)
|
||||
......................................................................
|
||||
|
||||
**Note**: If you have installed “**apt-file**” package then we can also search the package using config files as shown below :
|
||||
|
||||
linuxtechi@localhost:~$ apt-file search nagios.cfg
|
||||
ganglia-nagios-bridge: /usr/share/doc/ganglia-nagios-bridge/nagios.cfg
|
||||
nagios3-common: /etc/nagios3/nagios.cfg
|
||||
nagios3-common: /usr/share/doc/nagios3-common/examples/nagios.cfg.gz
|
||||
pnp4nagios-bin: /etc/pnp4nagios/nagios.cfg
|
||||
pnp4nagios-bin: /usr/share/doc/pnp4nagios/examples/nagios.cfg
|
||||
|
||||
### Example:3 Display the basic information of Specific package. ###
|
||||
|
||||
linuxtechi@localhost:~$ apt-cache show postfix
|
||||
Package: postfix
|
||||
Priority: optional
|
||||
Section: mail
|
||||
Installed-Size: 3524
|
||||
Maintainer: LaMont Jones <lamont@debian.org>
|
||||
Architecture: amd64
|
||||
Version: 2.11.1-1
|
||||
Replaces: mail-transport-agent
|
||||
Provides: default-mta, mail-transport-agent
|
||||
.....................................................
|
||||
|
||||
### Example:4 List the dependency of Package. ###
|
||||
|
||||
linuxtechi@localhost:~$ apt-cache depends postfix
|
||||
postfix
|
||||
Depends: libc6
|
||||
Depends: libdb5.3
|
||||
Depends: libsasl2-2
|
||||
Depends: libsqlite3-0
|
||||
Depends: libssl1.0.0
|
||||
|Depends: debconf
|
||||
Depends: <debconf-2.0>
|
||||
cdebconf
|
||||
debconf
|
||||
Depends: netbase
|
||||
Depends: adduser
|
||||
Depends: dpkg
|
||||
............................................
|
||||
|
||||
### Example:5 Display the Cache Statistics using apt-cache. ###
|
||||
|
||||
linuxtechi@localhost:~$ apt-cache stats
|
||||
Total package names: 60877 (1,218 k)
|
||||
Total package structures: 102824 (5,758 k)
|
||||
Normal packages: 71285
|
||||
Pure virtual packages: 1102
|
||||
Single virtual packages: 9151
|
||||
Mixed virtual packages: 1827
|
||||
Missing: 19459
|
||||
Total distinct versions: 74913 (5,394 k)
|
||||
Total distinct descriptions: 93792 (2,251 k)
|
||||
Total dependencies: 573443 (16.1 M)
|
||||
Total ver/file relations: 78007 (1,872 k)
|
||||
Total Desc/File relations: 93792 (2,251 k)
|
||||
Total Provides mappings: 16583 (332 k)
|
||||
Total globbed strings: 171 (2,263 )
|
||||
Total dependency version space: 2,665 k
|
||||
Total slack space: 37.3 k
|
||||
Total space accounted for: 29.5 M
|
||||
|
||||
### Example:6 Update the package repository using “apt-get update” ###
|
||||
|
||||
Using the command “apt-get update” , we can resynchronize the package index files from their sources repository. Package index are retrieved from the file located at “/etc/apt/sources.list”
|
||||
|
||||
linuxtechi@localhost:~$ sudo apt-get update
|
||||
Ign http://extras.ubuntu.com utopic InRelease
|
||||
Hit http://extras.ubuntu.com utopic Release.gpg
|
||||
Hit http://extras.ubuntu.com utopic Release
|
||||
Hit http://extras.ubuntu.com utopic/main Sources
|
||||
Hit http://extras.ubuntu.com utopic/main amd64 Packages
|
||||
Hit http://extras.ubuntu.com utopic/main i386 Packages
|
||||
Ign http://in.archive.ubuntu.com utopic InRelease
|
||||
Ign http://in.archive.ubuntu.com utopic-updates InRelease
|
||||
Ign http://in.archive.ubuntu.com utopic-backports InRelease
|
||||
................................................................
|
||||
|
||||
### Example:7 Install a package using apt-get command. ###
|
||||
|
||||
linuxtechi@localhost:~$ sudo apt-get install icinga
|
||||
|
||||
In the above example we are installing a package named “icinga”
|
||||
|
||||
### Example:8 Upgrade all the Installed Packages ###
|
||||
|
||||
linuxtechi@localhost:~$ sudo apt-get upgrade
|
||||
|
||||
### Example:9 Upgrade a Particular Package. ###
|
||||
|
||||
“install” option along with “–only-upgrade” in apt-get command is used to upgrade a particular package , example is shown below :
|
||||
|
||||
linuxtechi@localhost:~$ sudo apt-get install filezilla --only-upgrade
|
||||
|
||||
### Example:10 Removing a package using apt-get command. ###
|
||||
|
||||
linuxtechi@localhost:~$ sudo apt-get remove skype
|
||||
|
||||
Above command will remove or delete the skype package only , if you want to delete its config files then use the “purge” option in the apt-get command. Example is shown below :
|
||||
|
||||
linuxtechi@localhost:~$ sudo apt-get purge skype
|
||||
|
||||
We can also use the combination of above commands :
|
||||
|
||||
linuxtechi@localhost:~$ sudo apt-get remove --purge skype
|
||||
|
||||
### Example:11 Download the package in the Current Working Directory ###
|
||||
|
||||
linuxtechi@localhost:~$ sudo apt-get download icinga
|
||||
Get:1 http://in.archive.ubuntu.com/ubuntu/ utopic/universe icinga amd64 1.11.6-1build1 [1,474 B]
|
||||
Fetched 1,474 B in 1s (1,363 B/s)
|
||||
|
||||
Above command will download icinga package in your current working directory.
|
||||
|
||||
### Example:12 Clear disk Space used by retrieved package files. ###
|
||||
|
||||
linuxtechi@localhost:~$ sudo apt-get clean
|
||||
|
||||
Above Command will clear the disk space used by apt-get command while retrieving(download) packages.
|
||||
|
||||
We can also use “**autoclean**” option in place of “**clean**“, the main difference between them is that autoclean removes package files that can no longer be downloaded, and are largely useless.
|
||||
|
||||
linuxtechi@localhost:~$ sudo apt-get autoclean
|
||||
Reading package lists... Done
|
||||
Building dependency tree
|
||||
Reading state information... Done
|
||||
|
||||
### Example:13 Remove Packages using “autoremove” option. ###
|
||||
|
||||
When we use “autoremove” option with apt-get command , then it will remove the packages that were installed to satisfy the dependency of other packages and are now no longer needed or used.
|
||||
|
||||
linuxtechi@localhost:~$ sudo apt-get autoremove icinga
|
||||
|
||||
### Example:14 Display Changelog of a Package. ###
|
||||
|
||||
linuxtechi@localhost:~$ sudo apt-get changelog apache2
|
||||
Get:1 Changelog for apache2 (http://changelogs.ubuntu.com/changelogs/pool/main/a/apache2/apache2_2.4.10-1ubuntu1/changelog) [195 kB]
|
||||
Fetched 195 kB in 3s (60.9 kB/s)
|
||||
|
||||
Above Command will download the changelog of apache2 package and will display through sensible-pager on your screen.
|
||||
|
||||
### Example:15 List broken dependencies using “check” option ###
|
||||
|
||||
linuxtechi@localhost:~$ sudo apt-get check
|
||||
Reading package lists... Done
|
||||
Building dependency tree
|
||||
Reading state information... Done
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://www.linuxtechi.com/ubuntu-apt-get-apt-cache-commands-examples/
|
||||
|
||||
作者：[Pradeep Kumar][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://www.linuxtechi.com/author/pradeep/
|
||||
@ -0,0 +1,275 @@
|
||||
如何在 Linux 上使用 HAProxy 配置 HTTP 负载均衡器
|
||||
================================================================================
|
||||
随着基于 Web 的应用和服务的增多，IT 系统管理员肩上的责任也越来越重。当遇到不可预期的事件如流量达到高峰，流量增大或者内部的挑战比如硬件的损坏或紧急维修，无论如何，你的 Web 应用都必须要保持可用性。甚至现在流行的 devops 和持续交付也可能威胁到你的 Web 服务的可靠性和性能的一致性。
|
||||
|
||||
不可预测，不一直的性能表现是你无法接受的。但是我们怎样消除这些缺点呢？大多数情况下一个合适的负载均衡解决方案可以解决这个问题。今天我会给你们介绍如何使用 [HAProxy][1] 配置 HTTP 负载均衡器。
|
||||
|
||||
###什么是 HTTP 负载均衡？ ###
|
||||
|
||||
HTTP 负载均衡是一个网络解决方案，它将发入的 HTTP 或 HTTPs 请求分配至一组提供相同的 Web 应用内容的服务器用于响应。通过将请求在这样的多个服务器间进行均衡，负载均衡器可以防止服务器出现单点故障，可以提升整体的可用性和响应速度。它还可以让你能够简单的通过添加或者移除服务器来进行横向扩展或收缩，对工作负载进行调整。
|
||||
|
||||
### 什么时候，什么情况下需要使用负载均衡？ ###
|
||||
|
||||
负载均衡可以提升服务器的使用性能和最大可用性，当你的服务器开始出现高负载时就可以使用负载均衡。或者你在为一个大型项目设计架构时，在前端使用负载均衡是一个很好的习惯。当你的环境需要扩展的时候它会很有用。
|
||||
|
||||
|
||||
### 什么是 HAProxy？ ###
|
||||
|
||||
HAProxy 是一个流行的开源的 GNU/Linux 平台下的 TCP/HTTP 服务器的负载均衡和代理软件。HAProxy 是单线程，事件驱动架构，可以轻松的处理 [10 Gbps 速率][2] 的流量，在生产环境中被广泛的使用。它的功能包括自动健康状态检查，自定义负载均衡算法，HTTPS/SSL 支持，会话速率限制等等。
|
||||
|
||||
### 这个教程要实现怎样的负载均衡 ###
|
||||
|
||||
在这个教程中，我们会为 HTTP Web 服务器配置一个基于 HAProxy 的负载均衡。
|
||||
|
||||
### 准备条件 ###
|
||||
|
||||
你至少要有一台，或者最好是两台 Web 服务器来验证你的负载均衡的功能。我们假设后端的 HTTP Web 服务器已经配置好并[可以运行][3]。
|
||||
You will need at least one, or preferably two web servers to verify functionality of your load balancer. We assume that backend HTTP web servers are already [up and running][3].
|
||||
|
||||
### 在 Linux 中安装 HAProxy ###
|
||||
|
||||
对于大多数的发行版，我们可以使用发行版的包管理器来安装 HAProxy。
|
||||
|
||||
#### 在 Debian 中安装 HAProxy ####
|
||||
|
||||
在 Debian Wheezy 中我们需要添加源，在 /etc/apt/sources.list.d 下创建一个文件 "backports.list" ，写入下面的内容
|
||||
|
||||
deb http://cdn.debian.net/debian wheezybackports main
|
||||
|
||||
刷新仓库的数据，并安装 HAProxy
|
||||
|
||||
# apt get update
|
||||
# apt get install haproxy
|
||||
|
||||
#### 在 Ubuntu 中安装 HAProxy ####
|
||||
|
||||
# apt get install haproxy
|
||||
|
||||
#### 在 CentOS 和 RHEL 中安装 HAProxy ####
|
||||
|
||||
# yum install haproxy
|
||||
|
||||
### 配置 HAProxy ###
|
||||
|
||||
本教程假设有两台运行的 HTTP Web 服务器，它们的 IP 地址是 192.168.100.2 和 192.168.100.3。我们将负载均衡配置在 192.168.100.4 的这台服务器上。
|
||||
|
||||
为了让 HAProxy 工作正常，你需要修改 /etc/haproxy/haproxy.cfg 中的一些选项。我们会在这一节中解释这些修改。一些配置可能因 GNU/Linux 发行版的不同而变化，这些会被标注出来。
|
||||
|
||||
#### 1. 配置日志功能 ####
|
||||
|
||||
你要做的第一件事是为 HAProxy 配置日志功能，在排错时日志将很有用。日志配置可以在 /etc/haproxy/haproxy.cfg 的 global 段中找到他们。下面是针对不同的 Linux 发型版的 HAProxy 日志配置。
|
||||
|
||||
**CentOS 或 RHEL:**
|
||||
|
||||
在 CentOS/RHEL中启用日志，将下面的：
|
||||
|
||||
log 127.0.0.1 local2
|
||||
|
||||
替换为：
|
||||
|
||||
log 127.0.0.1 local0
|
||||
|
||||
然后配置 HAProxy 在 /var/log 中的日志分割，我们需要修改当前的 rsyslog 配置。为了简洁和明了，我们在 /etc/rsyslog.d 下创建一个叫 haproxy.conf 的文件，添加下面的内容：
|
||||
|
||||
$ModLoad imudp
|
||||
$UDPServerRun 514
|
||||
$template Haproxy,"%msg%\n"
|
||||
local0.=info /var/log/haproxy.log;Haproxy
|
||||
local0.notice /var/log/haproxystatus.log;Haproxy
|
||||
local0.* ~
|
||||
|
||||
这个配置会基于 $template 在 /var/log 中分割 HAProxy 日志。现在重启 rsyslog 应用这些更改。
|
||||
|
||||
# service rsyslog restart
|
||||
|
||||
**Debian 或 Ubuntu:**
|
||||
|
||||
在 Debian 或 Ubuntu 中启用日志，将下面的内容
|
||||
|
||||
log /dev/log local0
|
||||
log /dev/log local1 notice
|
||||
|
||||
替换为：
|
||||
|
||||
log 127.0.0.1 local0
|
||||
|
||||
然后为 HAProxy 配置日志分割，编辑 /etc/rsyslog.d/ 下的 haproxy.conf （在 Debian 中可能叫 49-haproxy.conf），写入下面你的内容
|
||||
|
||||
$ModLoad imudp
|
||||
$UDPServerRun 514
|
||||
$template Haproxy,"%msg%\n"
|
||||
local0.=info /var/log/haproxy.log;Haproxy
|
||||
local0.notice /var/log/haproxystatus.log;Haproxy
|
||||
local0.* ~
|
||||
|
||||
这个配置会基于 $template 在 /var/log 中分割 HAProxy 日志。现在重启 rsyslog 应用这些更改。
|
||||
|
||||
# service rsyslog restart
|
||||
|
||||
#### 2. 设置默认选项 ####
|
||||
|
||||
下一步是设置 HAProxy 的默认选项。在 /etc/haproxy/haproxy.cfg 的 default 段中，替换为下面的配置：
|
||||
|
||||
defaults
|
||||
log global
|
||||
mode http
|
||||
option httplog
|
||||
option dontlognull
|
||||
retries 3
|
||||
option redispatch
|
||||
maxconn 20000
|
||||
contimeout 5000
|
||||
clitimeout 50000
|
||||
srvtimeout 50000
|
||||
|
||||
上面的配置是当 HAProxy 为 HTTP 负载均衡时建议使用的，但是并不一定是你的环境的最优方案。你可以自己研究 HAProxy 的手册并配置它。
|
||||
|
||||
#### 3. Web 集群配置 ####
|
||||
|
||||
Web 集群配置定义了一组可用的 HTTP 服务器。我们的负载均衡中的大多数设置都在这里。现在我们会创建一些基本配置，定义我们的节点。将配置文件中从 frontend 段开始的内容全部替换为下面的：
|
||||
|
||||
listen webfarm *:80
|
||||
mode http
|
||||
stats enable
|
||||
stats uri /haproxy?stats
|
||||
stats realm Haproxy\ Statistics
|
||||
stats auth haproxy:stats
|
||||
balance roundrobin
|
||||
cookie LBN insert indirect nocache
|
||||
option httpclose
|
||||
option forwardfor
|
||||
server web01 192.168.100.2:80 cookie node1 check
|
||||
server web02 192.168.100.3:80 cookie node2 check
|
||||
|
||||
"listen webfarm *:80" 定义了负载均衡器监听的地址和端口。为了教程的需要，我设置为 "\*" 表示监听在所有接口上。在真实的场景汇总，这样设置可能不太合适，应该替换为可以从 internet 访问的那个网卡接口。
|
||||
|
||||
stats enable
|
||||
stats uri /haproxy?stats
|
||||
stats realm Haproxy\ Statistics
|
||||
stats auth haproxy:stats
|
||||
|
||||
上面的设置定义了，负载均衡器的状态统计信息可以通过 http://<load-balancer-IP>/haproxy?stats 访问。访问需要简单的 HTTP 认证，用户名为 "haproxy" 密码为 "stats"。这些设置可以替换为你自己的认证方式。如果你不需要状态统计信息，可以完全禁用掉。
|
||||
|
||||
下面是一个 HAProxy 统计信息的例子
|
||||
|
||||
|
||||
|
||||
"balance roundrobin" 这一行表明我们使用的负载均衡类型。这个教程中，我们使用简单的轮询算法，可以完全满足 HTTP 负载均衡的需要。HAProxy 还提供其他的负载均衡类型：
|
||||
|
||||
- **leastconn**：将请求调度至连接数最少的服务器
|
||||
- **source**：对请求的客户端 IP 地址进行哈希计算，根据哈希值和服务器的权重将请求调度至后端服务器。
|
||||
- **uri**：对 URI 的左半部分（问号之前的部分）进行哈希，根据哈希结果和服务器的权重对请求进行调度
|
||||
- **url_param**：根据每个 HTTP GET 请求的 URL 查询参数进行调度，使用固定的请求参数将会被调度至指定的服务器上
|
||||
- **hdr(name**)：根据 HTTP 首部中的 <name> 字段来进行调度
|
||||
|
||||
"cookie LBN insert indirect nocache" 这一行表示我们的负载均衡器会存储 cookie 信息，可以将后端服务器池中的节点与某个特定会话绑定。节点的 cookie 存储为一个自定义的名字。这里，我们使用的是 "LBN"，你可以指定其他的名称。后端节点会保存这个 cookie 的会话。
|
||||
|
||||
server web01 192.168.100.2:80 cookie node1 check
|
||||
server web02 192.168.100.3:80 cookie node2 check
|
||||
|
||||
上面是我们的 Web 服务器节点的定义。服务器有由内部名称（如web01，web02），IP 地址和唯一的 cookie 字符串表示。cookie 字符串可以自定义，我这里使用的是简单的 node1，node2 ... node(n)
|
||||
|
||||
### 启动 HAProxy ###
|
||||
|
||||
如果你完成了配置，现在启动 HAProxy 并验证是否运行正常。
|
||||
|
||||
#### 在 Centos/RHEL 中启动 HAProxy ####
|
||||
|
||||
让 HAProxy 开机自启，使用下面的命令
|
||||
|
||||
# chkconfig haproxy on
|
||||
# service haproxy start
|
||||
|
||||
当然，防火墙需要开放 80 端口，想下面这样
|
||||
|
||||
**CentOS/RHEL 7 的防火墙**
|
||||
|
||||
# firewallcmd permanent zone=public addport=80/tcp
|
||||
# firewallcmd reload
|
||||
|
||||
**CentOS/RHEL 6 的防火墙**
|
||||
|
||||
把下面内容加至 /etc/sysconfig/iptables 中的 ":OUTPUT ACCEPT" 段中
|
||||
|
||||
A INPUT m state state NEW m tcp p tcp dport 80 j ACCEPT
|
||||
|
||||
重启**iptables**：
|
||||
|
||||
# service iptables restart
|
||||
|
||||
#### 在 Debian 中启动 HAProxy ####
|
||||
|
||||
#### 启动 HAProxy ####
|
||||
|
||||
# service haproxy start
|
||||
|
||||
不要忘了防火墙开放 80 端口，在 /etc/iptables.up.rules 中加入：
|
||||
|
||||
A INPUT p tcp dport 80 j ACCEPT
|
||||
|
||||
#### 在 Ubuntu 中启动HAProxy ####
|
||||
|
||||
让 HAProxy 开机自动启动在 /etc/default/haproxy 中配置
|
||||
|
||||
ENABLED=1
|
||||
|
||||
启动 HAProxy：
|
||||
|
||||
# service haproxy start
|
||||
|
||||
防火墙开放 80 端口：
|
||||
|
||||
# ufw allow 80
|
||||
|
||||
### 测试 HAProxy ###
|
||||
|
||||
检查 HAProxy 是否工作正常，我们可以这样做
|
||||
|
||||
首先准备一个 test.php 文件，文件内容如下
|
||||
|
||||
<?php
|
||||
header('Content-Type: text/plain');
|
||||
echo "Server IP: ".$_SERVER['SERVER_ADDR'];
|
||||
echo "\nX-Forwarded-for: ".$_SERVER['HTTP_X_FORWARDED_FOR'];
|
||||
?>
|
||||
|
||||
这个 PHP 文件会告诉我们哪台服务器（如负载均衡）转发了请求，哪台后端 Web 服务器实际处理了请求。
|
||||
|
||||
将这个 PHP 文件放到两个后端 Web 服务器的 Web 根目录中。然后用 curl 命令通过负载均衡器（192.168.100.4）访问这个文件
|
||||
|
||||
$ curl http://192.168.100.4/test.php
|
||||
|
||||
我们多次使用这个命令此时，会发现交替的输出下面的内容（因为使用了轮询算法）：
|
||||
|
||||
Server IP: 192.168.100.2
|
||||
X-Forwarded-for: 192.168.100.4
|
||||
|
||||
----------
|
||||
|
||||
Server IP: 192.168.100.3
|
||||
X-Forwarded-for: 192.168.100.4
|
||||
|
||||
如果我们停掉一台后端 Web 服务，curl 命令仍然正常工作，请求被分发至另一台可用的 Web 服务器。
|
||||
|
||||
### 总结 ###
|
||||
|
||||
现在你有了一个完全可用的负载均衡器，以轮询的模式对你的 Web 节点进行负载均衡。还可以去实验其他的配置选项以适应你的环境。希望这个教程可以帮会组你们的 Web 项目有更好的可用性。
|
||||
|
||||
你可能已经发现了，这个教程只包含单台负载均衡的设置。这意味着我们仍然有单点故障的问题。在真实场景中，你应该至少部署 2 台或者 3 台负载均衡以防止意外发生，但这不是本教程的范围。
|
||||
|
||||
如果 你有任何问题或建议，请在评论中提出，我会尽我的努力回答。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://xmodulo.com/haproxy-http-load-balancer-linux.html
|
||||
|
||||
作者：[Jaroslav Štěpánek][a]
|
||||
译者：[Liao](https://github.com/liaoishere)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://xmodulo.com/author/jaroslav
|
||||
[1]:http://www.haproxy.org/
|
||||
[2]:http://www.haproxy.org/10g.html
|
||||
[3]:http://xmodulo.com/how-to-install-lamp-server-on-ubuntu.html
|
||||
298
translated/tech/20141027 ntpq -p output.md
Normal file
298
translated/tech/20141027 ntpq -p output.md
Normal file
@ -0,0 +1,298 @@
|
||||
“ntpq -p”命令输出详解
|
||||
================================================================================
|
||||
[Gentoo][1]（也许其他发行版也是？）中 ["ntp -q" 的 man page][2] 只有简短的描述：“*打印出服务器已知的节点列表和它们的状态概要信息。*”
|
||||
|
||||
我还没见到关于这个命令的说明文档，因此这里对此作一个总结，可以补充进 "[man ntpq][3]" man page 中。更多的细节见这里 “[ntpq – standard NTP query program][4]”（原作者），和 [其他关于 man ntpq 的例子][5].
|
||||
|
||||
[NTP][6] 是一个设计用于通过 [udp][9] 网络 ([WAN][7] 或者 [LAN][8]) 来同步计算机时钟的协议。引用 [Wikipedia – NTP][10]：
|
||||
[NTP][6] is a protocol designed to synchronize the clocks of computers over a ([WAN][7] or [LAN][8]) [udp][9] network. From [Wikipedia – NTP][10]:
|
||||
|
||||
> 网络时间协议（英语：Network Time Protocol，NTP）一种协议和软件实现，用于通过使用有网络延迟的报文交换网络同步计算机系统间的时钟。最初由美国特拉华大学的 David L. Mills 设计，现在仍然由他和志愿者小组维护，它于 1985 年之前开始使用，是因特网中最老的协议之一。
|
||||
|
||||
想了解更多有关时间和 NTP 协议的知识，可以参考 “[The NTP FAQ, Time, what Time?][11]”和 [RFCs for NTP][12]。早期的“Network Time Protocol (Version 3) RFC” ([txt][13], or [pdf][14], Appendix E, The NTP Timescale and its Chronometry, p70) 包含了对过去 5000 年我们的计时系统的变化和关系的有趣解释。维基百科的文章 [Time][15] 和 [Calendar][16] 提供了更宏观的视角。
|
||||
|
||||
命令 "ntpq -q" 输出下面这样的一个表：
|
||||
|
||||
remote refid st t when poll reach delay offset jitter
|
||||
==============================================================================
|
||||
LOCAL(0) .LOCL. 10 l 96h 64 0 0.000 0.000 0.000
|
||||
*ns2.example.com 10.193.2.20 2 u 936 1024 377 31.234 3.353 3.096
|
||||
|
||||
### 更多细节 ###
|
||||
|
||||
#### 表头 ####
|
||||
|
||||
|
||||
- **remote** – 用于同步的远程节点或服务器。“LOCAL”表示本机 （当没有远程服务器可用时会出现）
|
||||
- **refid** – 远程的服务器进行同步的更高一级服务器
|
||||
- **st** – 远程节点或服务器的 [Stratum][17]（级别，NTP 时间同步是分层的）
|
||||
- **t** – 类型 (u: [unicast（单播）][18] 或 [manycast（选播）][19] 客户端, b: [broadcast（广播）][20] 或 [multicast（多播）][21] 客户端, l: 本地时钟, s: 对称节点（用于备份）, A: 选播服务器, B: 广播服务器, M: 多播服务器, 参见“[Automatic Server Discovery][22]“)
|
||||
- **when** – 最后一次同步到现在的时间 (默认单位为秒, “h”表示小时，“d”表示天)
|
||||
- **poll** – 同步的频率：[rfc5905][23]建议在 NTPv4 中这个值的范围在 4 (16s) 至 17 (36h) 之间（2的指数次秒），然而观察发现这个值的实际大小在一个小的多的范围内 ：64 (2的6次方)秒 至 1024 (2的10次方)秒
|
||||
- **reach** – 一个8位的左移移位寄存器值，用来测试能否和服务器连接，每成功连接一次它的值就会增加，以 [8 进制][24]显示
|
||||
- **delay** – 从本地到远程节点或服务器通信的往返时间（毫秒）
|
||||
- **offset** – 主机与远程节点或服务器时间源的时间偏移量，offset 越接近于0，主机和 NTP 服务器的时间越接近([方均根][25]表示，单位为毫秒)
|
||||
- **jitter** – 与远程节点同步的时间源的平均偏差（多个时间样本中的 offset 的偏差，单位是毫秒），这个数值的绝对值越小，主机的时间就越精确
|
||||
|
||||
#### 字段的统计代码 ####
|
||||
|
||||
表中第一个字符（统计代码）是状态标识（参见 [Peer Status Word][26]），包含 " "，"x"，"-"，"#"，"+"，"*"，"o"：
|
||||
|
||||
- " " – 无状态，表示:
|
||||
- 没有远程通信的主机
|
||||
- "LOCAL" 即本机
|
||||
- （未被使用的）高层级服务器
|
||||
- 远程主机使用的这台机器作为同步服务器
|
||||
- “**x**” – 已不再使用
|
||||
- “**-**” – 已不再使用
|
||||
- “**#**” – 良好的远程节点或服务器但是未被使用 （不在按同步距离排序的前六个节点中，作为备用节点使用）
|
||||
- “**+**” – 良好的且优先使用的远程节点或服务器（包含在组合算法中）
|
||||
- “*****” – 当前作为优先主同步对象的远程节点或服务器
|
||||
- “**o**” – PPS 节点 (当优先节点是有效时)。实际的系统同步是源于秒脉冲信号（pulse-per-second，PPS），可能通过PPS 时钟驱动或者通过内核接口。
|
||||
|
||||
参考 [Clock Select Algorithm][27].
|
||||
|
||||
#### refid ####
|
||||
|
||||
**refid** 有下面这些状态值
|
||||
|
||||
- 一个IP地址 – 远程节点或服务器的 [IP 地址][28]
|
||||
- **.LOCL.** – 本机 (当没有远程节点或服务器可用时）
|
||||
- **.PPS.** – 时间标准中的“[Pulse Per Second][29]”（秒脉冲）
|
||||
- **.IRIG.** – [Inter-Range Instrumentation Group][30] 时间码
|
||||
- **.ACTS.** – 美国 [NIST 标准时间][31] 电话调制器
|
||||
- **.NIST.** –美国 NIST 标准时间电话调制器
|
||||
- **.PTB.** – 德国 [PTB][32] 时间标准电话调制器
|
||||
- **.USNO.** – 美国 [USNO 标准时间][33] 电话调制器
|
||||
- **.CHU.** – [CHU][34] ([HF][35], Ottawa, ON, Canada) 标准时间无线电接收器
|
||||
- **.DCFa.** – [DCF77][36] ([LF][37], Mainflingen, Germany) 标准时间无线电接收器
|
||||
- **.HBG.** – [HBG][38] (LF Prangins, Switzerland) 标准时间无线电接收器
|
||||
- **.JJY.** – [JJY][39] (LF Fukushima, Japan) 标准时间无线电接收器
|
||||
- **.LORC.** – [LORAN][40]-C station ([MF][41]) 标准时间无线电接收器，注： [不再可用][42] (被 [eLORAN][43] 废弃)
|
||||
- **.MSF.** – [MSF][44] (LF, Anthorn, Great Britain) 标准时间无线电接收器
|
||||
- **.TDF.** – [TDF][45] (MF, Allouis, France)标准时间无线电接收器
|
||||
- **.WWV.** – [WWV][46] (HF, Ft. Collins, CO, America) 标准时间无线电接收器
|
||||
- **.WWVB.** – [WWVB][47] (LF, Ft. Collins, CO, America) 标准时间无线电接收器
|
||||
- **.WWVH.** – [WWVH][48] (HF, Kauai, HI, America) 标准时间无线电接收器
|
||||
- **.GOES.** – 美国 [静止环境观测卫星][49];
|
||||
- **.GPS.** – 美国 [GPS][50];
|
||||
- **.GAL.** – [伽利略定位系统][51] 欧洲 [GNSS][52];
|
||||
- **.ACST.** – 选播服务器
|
||||
- **.AUTH.** – 认证错误
|
||||
- **.AUTO.** – Autokey （NTP 的一种认证机制）顺序错误
|
||||
- **.BCST.** – 广播服务器
|
||||
- **.CRYPT.** – Autokey 协议错误
|
||||
- **.DENY.** – 服务器拒绝访问;
|
||||
- **.INIT.** – 关联初始化
|
||||
- **.MCST.** – 多播服务器
|
||||
- **.RATE.** – (轮询) 速率超出限定
|
||||
- **.TIME.** – 关联超时
|
||||
- **.STEP.** – 间隔时长改变，偏移量比危险阈值小(1000ms) 比间隔时间 (125ms)大
|
||||
|
||||
#### 操作要点 ####
|
||||
|
||||
一个时间服务器只会报告时间信息而不会从客户端更新时间（单向更新），而一个节点可以更新其他同级节点的时间，结合出一个彼此同意的时间（双向更新）。
|
||||
|
||||
[初次启动][53]时：
|
||||
|
||||
> 除非使用 iburst 选项，客户端通常需要花几分钟来和服务器同步。如果客户端在启动时时间与 NTP 服务器的时间差大于 1000 秒，守护进程会退出并在系统日志中记录，让操作者手动设置时间差小于 1000 秒后再重新启动。如果时间差小于 1000 秒，但是大于 128 秒，会自动矫正间隔，并自动重启守护进程。
|
||||
|
||||
> 当第一次启动时，时间频率文件（通常是 ntp.drift 文件，记录时间偏移）不存在，守护进程进入一个特殊模式来矫正频率。当时钟不符合[规范][54]时这会需要 900 秒。当校正完成后，守护进程创建时间频率文件进入普通模式，并分步校正剩余的偏差。
|
||||
|
||||
NTP 0 层（Stratum 0 ）的设备如原子钟（铯，铷），GPS 时钟或者其他标准时间的无线电时钟为 1 层（Stratum 1）的时间服务器提供时间信号。NTP 只报告[UTC][55] 时间（统一协调时，Coordinated Universal Time）。客户端程序使用[时区][56]从 UTC 导出本地时间。
|
||||
|
||||
NTP 协议是高精度的，使用的精度小于纳秒（2的 -32 次方）。主机的时间精度和其他参数（受硬件和操作系统限制）使用命令 “ntpq -c rl” 查看（参见 [rfc1305][57] 通用变量和 [rfc5905][58]）。
|
||||
|
||||
#### “ntpq -c rl”输出参数 ####
|
||||
|
||||
- **precision** 为四舍五入值，且为 2 的幂数。因此精度为 2 的 *precision* 此幂（秒）
|
||||
- **rootdelay** – 与同步网络中主同步服务器的总往返延时。注意这个值可以是正数或者负数，取决于时钟的精度。
|
||||
- **rootdisp** – 相对于同步网络中主同步服务器的偏差(秒)
|
||||
- **tc** – NTP 算法 [PLL][59] （phase locked loop，锁相环路） 或 [FLL][60] (frequency locked loop，锁频回路) 时间常量
|
||||
- **mintc** – NTP 算法 PLL/FLL 最小时间常亮或“最快响应
|
||||
- **offset** – 由结合算法得出的系统时钟偏移量（毫秒）
|
||||
- **frequency** – 系统时钟频率
|
||||
- **sys_jitter** – 由结合算法得出的系统时钟平均偏差（毫秒）
|
||||
- **clk_jitter** – 硬件时钟平均偏差（毫秒）
|
||||
- **clk_wander** – 硬件时钟偏移([PPM][61] – 百分之一)
|
||||
|
||||
Jitter (也叫 timing jitter) 表示短期变化大于10HZ 的频率， wander 表示长期变化大于10HZ 的频率 （Stability 表示系统的频率随时间的变化，和 aging, drift, trends 等是同义词）
|
||||
|
||||
#### 操作要点（续） ####
|
||||
|
||||
NTP 软件维护一系列连续更新的频率变化的校正值。对于设置正确的稳定系统，在非拥塞的网络中，现代硬件的 NTP 时钟同步通常与 UTC 标准时间相差在毫秒内。（在千兆 LAN 网络中可以达到何种精度？）
|
||||
|
||||
对于 UTC 时间，[闰秒][62] 可以每两年插入一次用于同步地球自传的变化。注意本地时间为[夏令时][63]时时间会有一小时的变化。在重同步之前客户端设备会使用独立的 UTC 时间，除非客户端使用了偏移校准。
|
||||
|
||||
#### [闰秒发生时会怎样][64] ####
|
||||
|
||||
> 闰秒发生时，会对当天时间增加或减少一秒。闰秒的调整在 UTC 时间当天的最后一秒。如果增加一秒，UTC 时间会出现 23:59:60。即 23:59:59 到 0:00:00 之间实际上需要 2 秒钟。如果减少一秒，时间会从 23:59:58 跳至 0:00:00 。另见 [The Kernel Discipline][65].
|
||||
|
||||
好了… 间隔阈值（step threshold）的真实值是多少: 125ms 还是 128ms？ PLL/FLL tc 的单位是什么 (log2 s? ms?)？在非拥塞的千兆 LAN 中时间节点间的精度能达到多少？
|
||||
|
||||
感谢 Camilo M 和 Chris B的评论。 欢迎校正错误和更多细节的探讨。
|
||||
|
||||
谢谢
|
||||
Martin
|
||||
|
||||
### 外传 ###
|
||||
|
||||
- [NTP 的纪元][66] 从 1900 开始而 UNIX 的从 1970开始.
|
||||
- [时间校正][67] 是逐渐进行的，因此时间的完全同步可能会画上几个小时。
|
||||
- [节点状态][68] 可以被记录到 [summarise/plot time offsets and errors][69]
|
||||
- [RMS][70] – 均方根
|
||||
- [PLL][71] – 锁相环路
|
||||
- [FLL][72] – 锁频回路
|
||||
- [PPM][73] – 百万分之一，用于描述频率的变化
|
||||
- [man ntpq (Gentoo 简明版本)][74]
|
||||
- [man ntpq (长期维护版本)][75]
|
||||
- [man ntpq (Gentoo 长期维护版本)][76]
|
||||
|
||||
### 另见 ###
|
||||
|
||||
- [ntpq – 标准 NTP 查询程序][77]
|
||||
- [The Network Time Protocol (NTP) 分布][78]
|
||||
- NTP 的简明 [历史][79]
|
||||
- 一个更多细节的简明历史 “Mills, D.L., A brief history of NTP time: confessions of an Internet timekeeper. Submitted for publication; please do not cite or redistribute” ([pdf][80])
|
||||
- [NTP RFC][81] 标准文档
|
||||
- Network Time Protocol (Version 3) RFC – [txt][82], or [pdf][83]. Appendix E, The NTP Timescale and its Chronometry, p70, 包含了对过去 5000 年我们的计时系统的变化和关系的有趣解释。
|
||||
- 维基百科: [Time][84] 和 [Calendar][85]
|
||||
- [John Harrison and the Longitude problem][86]
|
||||
- [Clock of the Long Now][87] – The 10,000 Year Clock
|
||||
- John C Taylor – [Chronophage][88]
|
||||
- [Orders of magnitude of time][89]
|
||||
- [Greenwich Time Signal][90]
|
||||
|
||||
### 其他 ###
|
||||
|
||||
SNTP （Simple Network Time Protocol, [RFC 4330][91]，简单未落协议）基本上也是NTP，但是缺少一些基于 [RFC 1305][92] 实现的 NTP 的一些不再需要的内部算法。
|
||||
|
||||
Win32 时间 [Windows Time Service][93] 是 SNTP 的非标准实现，没有精度的保证，并假设精度几乎有 1-2 秒的范围。（因为没有系统时间变化校正）
|
||||
|
||||
还有一个[PTP (IEEE 1588)][95] Precision Time Protocol（精准时间协议）。见维基百科：[Precision Time Protocol][96]。软件程序为 [PTPd][97]。虫咬的功能是这是一个 [LAN][98] 高精度主从同步系统，精度在毫秒级，使用 [International Atomic Time][99] (TAI， [monotonic][100]，无闰秒)。数据报时间戳需要在网卡中启用。支持 PTP 的网络会对数据报记录时间戳以减少交换机路由器的影响。也可以在不记录时间戳的网络中使用 PTP 但可能应为时间偏差太大而无法同步。因此使用这个需要对网络进行设置。
|
||||
|
||||
### 更老的时间同步协议 ###
|
||||
|
||||
- DTSS – DEC公司的数字时间同步服务， 被 NTP 所取代。例子： [DTSS VMS C code c2000][101]。 （哪里有关于 DTSS 的文章或文档吗？）
|
||||
- [DAYTIME protocol][102]，使用 [TCP][103] 或 [UDP][104] 13 端口同步
|
||||
- [ICMP Timestamp][105] 和 [ICMP Timestamp Reply][106]，使用 [ICMP][107] 协议同步
|
||||
- [Time Protocol][108]，使用 TCP 或 UDP 37 号端口同步
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://nlug.ml1.co.uk/2012/01/ntpq-p-output/831
|
||||
|
||||
作者：Martin L
|
||||
译者：[Liao](https://github.com/liaosishere)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
|
||||
|
||||
[1]:http://www.gentoo.org/
|
||||
[2]:http://nlug.ml1.co.uk/2012/01/man-ntpq-gentoo-brief-version/853
|
||||
[3]:http://www.thelinuxblog.com/linux-man-pages/1/ntpq
|
||||
[4]:http://www.eecis.udel.edu/~mills/ntp/html/ntpq.html
|
||||
[5]:http://linux.die.net/man/8/ntpq
|
||||
[6]:http://www.ntp.org/
|
||||
[7]:http://en.wikipedia.org/wiki/Wide_area_network
|
||||
[8]:http://en.wikipedia.org/wiki/Local_area_network
|
||||
[9]:http://en.wikipedia.org/wiki/User_Datagram_Protocol
|
||||
[10]:http://en.wikipedia.org/wiki/Network_Time_Protocol
|
||||
[11]:http://www.ntp.org/ntpfaq/NTP-s-time.htm
|
||||
[12]:http://www.ntp.org/rfc.html
|
||||
[13]:http://www.ietf.org/rfc/rfc1305.txt
|
||||
[14]:http://www.rfc-editor.org/rfc/rfc1305.pdf
|
||||
[15]:http://en.wikipedia.org/wiki/Time
|
||||
[16]:http://en.wikipedia.org/wiki/Calendar
|
||||
[17]:http://en.wikipedia.org/wiki/Network_Time_Protocol#Clock_strata
|
||||
[18]:http://en.wikipedia.org/wiki/Unicast
|
||||
[19]:http://www.eecis.udel.edu/~mills/ntp/html/manyopt.html#mcst
|
||||
[20]:http://en.wikipedia.org/wiki/Broadcasting_%28computing%29
|
||||
[21]:http://en.wikipedia.org/wiki/Multicast
|
||||
[22]:http://www.eecis.udel.edu/~mills/ntp/html/manyopt.html
|
||||
[23]:http://www.ietf.org/rfc/rfc5905.txt
|
||||
[24]:http://en.wikipedia.org/wiki/Octal#In_computers
|
||||
[25]:http://en.wikipedia.org/wiki/Root_mean_square
|
||||
[26]:http://www.eecis.udel.edu/~mills/ntp/html/decode.html#peer
|
||||
[27]:http://www.eecis.udel.edu/~mills/ntp/html/select.html
|
||||
[28]:http://en.wikipedia.org/wiki/Ip_address
|
||||
[29]:http://en.wikipedia.org/wiki/Pulse_per_second
|
||||
[30]:http://en.wikipedia.org/wiki/Inter-Range_Instrumentation_Group
|
||||
[31]:http://en.wikipedia.org/wiki/Standard_time_and_frequency_signal_service
|
||||
[32]:http://www.ptb.de/index_en.html
|
||||
[33]:http://en.wikipedia.org/wiki/United_States_Naval_Observatory#Time_service
|
||||
[34]:http://en.wikipedia.org/wiki/CHU_%28radio_station%29
|
||||
[35]:http://en.wikipedia.org/wiki/High_frequency
|
||||
[36]:http://en.wikipedia.org/wiki/DCF77
|
||||
[37]:http://en.wikipedia.org/wiki/Low_frequency
|
||||
[38]:http://en.wikipedia.org/wiki/HBG_%28time_signal%29
|
||||
[39]:http://en.wikipedia.org/wiki/JJY#Time_standards
|
||||
[40]:http://en.wikipedia.org/wiki/LORAN#Timing_and_synchronization
|
||||
[41]:http://en.wikipedia.org/wiki/Medium_frequency
|
||||
[42]:http://en.wikipedia.org/wiki/LORAN#The_future_of_LORAN
|
||||
[43]:http://en.wikipedia.org/wiki/LORAN#eLORAN
|
||||
[44]:http://en.wikipedia.org/wiki/Time_from_NPL#The_.27MSF_signal.27_and_the_.27Rugby_clock.27
|
||||
[45]:http://en.wikipedia.org/wiki/T%C3%A9l%C3%A9_Distribution_Fran%C3%A7aise
|
||||
[46]:http://en.wikipedia.org/wiki/WWV_%28radio_station%29#Time_signals
|
||||
[47]:http://en.wikipedia.org/wiki/WWVB
|
||||
[48]:http://en.wikipedia.org/wiki/WWVH
|
||||
[49]:http://en.wikipedia.org/wiki/GOES#Further_reading
|
||||
[50]:http://en.wikipedia.org/wiki/Gps#Timekeeping
|
||||
[51]:http://en.wikipedia.org/wiki/Galileo_%28satellite_navigation%29#The_concept
|
||||
[52]:http://en.wikipedia.org/wiki/Gnss
|
||||
[53]:http://www.eecis.udel.edu/~mills/ntp/html/debug.html
|
||||
[54]:http://www.ntp.org/ntpfaq/NTP-s-algo-kernel.htm
|
||||
[55]:http://en.wikipedia.org/wiki/Coordinated_Universal_Time
|
||||
[56]:http://en.wikipedia.org/wiki/Time_zone
|
||||
[57]:http://www.ietf.org/rfc/rfc1305.txt
|
||||
[58]:http://www.ietf.org/rfc/rfc5905.txt
|
||||
[59]:http://en.wikipedia.org/wiki/PLL
|
||||
[60]:http://en.wikipedia.org/wiki/Frequency-locked_loop
|
||||
[61]:http://en.wikipedia.org/wiki/Parts_per_million
|
||||
[62]:http://en.wikipedia.org/wiki/Leap_second
|
||||
[63]:http://en.wikipedia.org/wiki/Daylight_saving_time
|
||||
[64]:http://www.ntp.org/ntpfaq/NTP-s-time.htm#Q-TIME-LEAP-SECOND
|
||||
[65]:http://www.ntp.org/ntpfaq/NTP-s-algo-kernel.htm
|
||||
[66]:http://www.ntp.org/ntpfaq/NTP-s-algo.htm#AEN1895
|
||||
[67]:http://www.ntp.org/ntpfaq/NTP-s-algo.htm#Q-ACCURATE-CLOCK
|
||||
[68]:http://www.ntp.org/ntpfaq/NTP-s-trouble.htm#Q-TRB-MON-STATFIL
|
||||
[69]:http://www.ntp.org/ntpfaq/NTP-s-trouble.htm#AEN5086
|
||||
[70]:http://en.wikipedia.org/wiki/Root_mean_square
|
||||
[71]:http://en.wikipedia.org/wiki/PLL
|
||||
[72]:http://en.wikipedia.org/wiki/Frequency-locked_loop
|
||||
[73]:http://en.wikipedia.org/wiki/Parts_per_million
|
||||
[74]:http://nlug.ml1.co.uk/2012/01/man-ntpq-gentoo-brief-version/853
|
||||
[75]:http://nlug.ml1.co.uk/2012/01/man-ntpq-long-version/855
|
||||
[76]:http://nlug.ml1.co.uk/2012/01/man-ntpq-gentoo-long-version/856
|
||||
[77]:http://www.eecis.udel.edu/~mills/ntp/html/ntpq.html
|
||||
[78]:http://www.eecis.udel.edu/~mills/ntp/html/index.html
|
||||
[79]:http://www.ntp.org/ntpfaq/NTP-s-def-hist.htm
|
||||
[80]:http://www.eecis.udel.edu/~mills/database/papers/history.pdf
|
||||
[81]:http://www.ntp.org/rfc.html
|
||||
[82]:http://www.ietf.org/rfc/rfc1305.txt
|
||||
[83]:http://www.rfc-editor.org/rfc/rfc1305.pdf
|
||||
[84]:http://en.wikipedia.org/wiki/Time
|
||||
[85]:http://en.wikipedia.org/wiki/Calendar
|
||||
[86]:http://www.rmg.co.uk/harrison
|
||||
[87]:http://longnow.org/clock/
|
||||
[88]:http://johnctaylor.com/
|
||||
[89]:http://en.wikipedia.org/wiki/Orders_of_magnitude_%28time%29
|
||||
[90]:http://en.wikipedia.org/wiki/Greenwich_Time_Signal
|
||||
[91]:http://tools.ietf.org/html/rfc4330
|
||||
[92]:http://tools.ietf.org/html/rfc1305
|
||||
[93]:http://en.wikipedia.org/wiki/Network_Time_Protocol#Microsoft_Windows
|
||||
[94]:http://en.wikipedia.org/wiki/Personal_computer
|
||||
[95]:http://www.nist.gov/el/isd/ieee/ieee1588.cfm
|
||||
[96]:http://en.wikipedia.org/wiki/IEEE_1588
|
||||
[97]:http://ptpd.sourceforge.net/
|
||||
[98]:http://en.wikipedia.org/wiki/Local_area_network
|
||||
[99]:http://en.wikipedia.org/wiki/International_Atomic_Time
|
||||
[100]:http://en.wikipedia.org/wiki/Monotonic_function
|
||||
[101]:http://antinode.info/ftp/dtss_ntp/
|
||||
[102]:http://en.wikipedia.org/wiki/DAYTIME
|
||||
[103]:http://en.wikipedia.org/wiki/Transmission_Control_Protocol
|
||||
[104]:http://en.wikipedia.org/wiki/User_Datagram_Protocol
|
||||
[105]:http://en.wikipedia.org/wiki/ICMP_Timestamp
|
||||
[106]:http://en.wikipedia.org/wiki/ICMP_Timestamp_Reply
|
||||
[107]:http://en.wikipedia.org/wiki/Internet_Control_Message_Protocol
|
||||
[108]:http://en.wikipedia.org/wiki/Time_Protocol
|
||||
@ -1,25 +1,25 @@
|
||||
How To Install Websvn In CentOS 7
|
||||
CentOS 7中安装Websvn
|
||||
================================================================================
|
||||
**WebSVN** offers a view onto your subversion repositories that’s been designed to reflect the Subversion methodology. You can view the log of any file or directory and see a list of all the files changed, added or deleted in any given revision. You can also view the differences between two versions of a file so as to see exactly what was changed in a particular revision.
|
||||
**WebSVN**为你的Subversion提供了一个试图，它设计用来反映Subversion的一整套方法。你可以检查任何文件或目录的日志，以及查看任何指定修改库中修改、添加或删除过的文件列表。你也可以检查同一文件两个版本的不同之处，以便确切地查看某个特性修订版中的修改。
|
||||
|
||||
### Features ###
|
||||
### 特性 ###
|
||||
|
||||
WebSVN offers the following features:
|
||||
WebSVN提供了以下这些特性：
|
||||
|
||||
- Easy to use interface;
|
||||
- Customisable templating system;
|
||||
- Colourisation of file listings;
|
||||
- Blame view;
|
||||
- Log message searching;
|
||||
- RSS feed support.
|
||||
- 易于使用的界面；
|
||||
- 可自定义的模板系统；
|
||||
- 文件列表的着色；
|
||||
- 过错视图；
|
||||
- 日志信息搜索；
|
||||
- 支持RSS订阅；
|
||||
|
||||
### Installation ###
|
||||
### 安装 ###
|
||||
|
||||
I use the following link to install Subversion on CentOS 7.
|
||||
我使用以下链接来将Subversion安装到CentOS 7。
|
||||
|
||||
- [How To install Subversion On CentOS 7][1]
|
||||
- [CentOS 7上如何安装Subversion][1]
|
||||
|
||||
**1 – Download the websvn to /var/www/html.**
|
||||
**1 – 下载websvn到/var/www/html。**
|
||||
|
||||
cd /var/www/html
|
||||
|
||||
@ -27,7 +27,7 @@ I use the following link to install Subversion on CentOS 7.
|
||||
|
||||
wget http://websvn.tigris.org/files/documents/1380/49057/websvn-2.3.3.zip
|
||||
|
||||
**2 – Extract the zip package.**
|
||||
**2 – 解压zip包。**
|
||||
|
||||
unzip websvn-2.3.3.zip
|
||||
|
||||
@ -35,11 +35,11 @@ I use the following link to install Subversion on CentOS 7.
|
||||
|
||||
mv websvn-2.3.3 websvn
|
||||
|
||||
**3 – Installl php to your system.**
|
||||
**3 – 安装php到你的系统。**
|
||||
|
||||
yum install php
|
||||
|
||||
**4 – Edit web svn config.**
|
||||
**4 – 编辑web svn配置。**
|
||||
|
||||
cd /var/www/html/websvn/include
|
||||
|
||||
@ -82,20 +82,20 @@ I use the following link to install Subversion on CentOS 7.
|
||||
$extEnscript[".sh"] = "bash";
|
||||
~
|
||||
|
||||
save and exit.
|
||||
保存并退出。
|
||||
|
||||
**6 – Reload apache and start websvn link http://ip/websvn.**
|
||||
**6 – 重新加载apache并启动websvn链接http://ip/websvn。**
|
||||
|
||||
|
||||
|
||||
That’s it.
|
||||
一切搞定。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://www.unixmen.com/install-websvn-centos-7/
|
||||
|
||||
作者：[M.el Khamlichi][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
译者：[GOLinux](https://github.com/GOLinux)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
|
||||
77
translated/tech/Quick systemd-nspawn guide.md
Normal file
77
translated/tech/Quick systemd-nspawn guide.md
Normal file
@ -0,0 +1,77 @@
|
||||
systemd-nspawn 指南
|
||||
===========================
|
||||
我目前已从 chroot（译者注：chroot可以构建类似沙盒的环境，建议各位同学先了解chroot） 迁移到 systemd-nspawn，同时我写了一篇快速指南。简单的说，我强烈建议正在使用 systemd 的用户从 chroot 转为 systemd-nspawn，因为只要你的内核配置正确的话，它几乎没有什么缺点。
|
||||
|
||||
想必在各大发行版中的用户对 chroot 都不陌生，而且我猜想 Gentoo 用户要时不时的使用它。
|
||||
|
||||
###chroot 面临的挑战
|
||||
|
||||
大多数交互环境下，仅运行chroot还不够。通常还要挂载 /proc， /sys，另外为了确保不会出现类似“丢失 ptys”之类的错误，我们还得 bind（译者注：bind 是 mount 的一个选项） 挂载 /dev。如果你使用 tmpfs，你可能想要以 tmpfs 类型挂载新的 tmp， var/tmp。接下来你可能还想将其他的挂载点 bind 到 chroot 中。这些都不是特别难，但是一般情况下要写一个脚本来管理它。
|
||||
|
||||
现在我按照日常计划执行备份操作，当然有一些不必备份的数据如 tmp 目录，或任何 bind 挂载的内容。当我配置了一个新的 chroot 意味着我要更新我的备份配置了，但我经常忘记这点，因为大多数时间里 chroot 挂载点并没有运行。当这些挂载点任然存在的情况下执行备份的话，那么备份中会多出很多不需要的内容。
|
||||
|
||||
当 bind 挂载点包含其他挂载点时（比如挂载时使用 -rbind 选项），这种情况下 systemd 的默认处理方式略有不同。在 bind 挂载中卸载一些东西时，systemd 会将处于 bind 另一边的目录也卸载掉。想像一下，如果我卸载了 chroot 中以bind 挂载 /dev 的某个目录后发现主机上的 /dev/pts 与 /dev/shm 也不见了，我肯定会很吃惊。不过好像有其他方法可以避免，但是这不是我们此次讨论的重点。
|
||||
|
||||
### Systemd-nspawn 优点
|
||||
|
||||
Systemd-nspawn 用于启动一个容器，并且它的最简模式就可以像 chroot 那样运行。默认情况下，它自动配置容器所需的开销如 /dev, /tmp 等等。通过配合一些选项它也可配置其他的 bind 挂载点。当容器退出后，所有的挂载点都会被清除。
|
||||
|
||||
容器运行时，从外部看上去没什么变化。事实上，可以从同一个 chroot 产生5个不同的 systemd-nspawn 容器实例，并且除了文件系统（不包括 /dev, /tmp等，只有 /usr,/etc 的改变会传递）外它们之间没有任何联系。你的备份将会忽略 bind 挂载点、tmpfs 及任何挂载在容器中的内容。
|
||||
|
||||
它同时具有其它优秀容器的优点，比如 containment - 可以杀死容器内的所有活动但不影响外部，等等。它的安全性并不是无懈可击的-它的作用仅仅是防止意外的错误。
|
||||
|
||||
如果你使用的是兼容的 sysvinit（它包含了 systemd，openrc），你可以启动容器。这意味着，你可以在容器中使用 fstab 添加挂载点，运行守护进程等。只需要一个 chroot 的开销，几乎就可以获得虚拟化的所有好处（不需要构建内核等）。在一个看起来像 chroot 的容器中运行systemctl poweroff 看起来很奇怪，但这条命令能够起作用。
|
||||
|
||||
注意，如果不做额外配置的话那么容器就会共享主机的网络，所以主机上的容器不要运行 sshd。运行一个分离的网络 namespace 不是太难，为了新的实例可以使用DHCP，分离之后记得绑定接口。
|
||||
|
||||
###操作步骤
|
||||
|
||||
让它工作起来是此次讨论中最简短的部分了。
|
||||
|
||||
首先系统内核要支持 namespaces 与 devpts：
|
||||
|
||||
CONFIG_UTS_NS=y
|
||||
CONFIG_IPC_NS=y
|
||||
CONFIG_USER_NS=y
|
||||
CONFIG_PID_NS=y
|
||||
CONFIG_NET_NS=y
|
||||
CONFIG_DEVPTS_MULTIPLE_INSTANCES=y
|
||||
|
||||
像 chroot 那样启动 namespace 是非常简单的：
|
||||
|
||||
systemd-nspawn -D .
|
||||
|
||||
也可以像 chroot 那样退出。在内部可以运行 mount 并且可以看到默认它已将 /dev 与 /tmp 准备好了。 ”.“就是 chroot 的路径，也就是当前路径。在它内部运行的是 bash。
|
||||
|
||||
如果要添加一些 bind 挂载点也非常简便：
|
||||
|
||||
systemd-nspawn -D . --bind /usr/portage
|
||||
|
||||
现在，容器中的 /usr/portage 就与主机的对应目录绑定起来了，我们无需 sync /etc。如果想要绑定到指定的路径，只要在原路径后添加 ”：dest“，相当于 chroot 的 root（--bind foo 与 --bind foo:foo是一样的）。
|
||||
|
||||
如果容器具有 init 功能并且可以在内部运行，可以通过添加 -b 选项启动它：
|
||||
|
||||
systemd-nspawn -D . --bind /usr/portage -b
|
||||
|
||||
可以观察到 init 的运作。关闭容器会自动退出。
|
||||
|
||||
如果容器内运行了 systemd ，你可以使用 -h 选项将它的日志重定向到主机的systemd日志：
|
||||
|
||||
systemd-nspawn -D . --bind /usr/portage -j -b
|
||||
|
||||
使用 nspawn 注册容器以便它能够在 machinectl 中显示。如此可以方便的在主机上对它进行操作，如启动新的 getty， ssh 连接，关机等。
|
||||
|
||||
如果你正在使用 systemd 那么甩开 chroot 拥抱 nspawn 吧。
|
||||
|
||||
---------------------
|
||||
|
||||
via: http://rich0gentoo.wordpress.com/2014/07/14/quick-systemd-nspawn-guide/
|
||||
|
||||
作者：[rich0][a]
|
||||
译者：[SPccman](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://rich0gentoo.wordpress.com/
|
||||
|
||||
Loading…
Reference in New Issue
Block a user