From e4f8808dc91ca8cf102ce96d947cd886b8c9c871 Mon Sep 17 00:00:00 2001 From: Ezio Date: Tue, 7 Feb 2017 09:16:59 +0800 Subject: [PATCH] =?UTF-8?q?20170206-2=20=E9=80=89=E9=A2=98?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...te Ports are Reachable Using nc Command.md | 69 +++++++++++++++++++ 1 file changed, 69 insertions(+) create mode 100644 sources/tech/20170206 How to Check Remote Ports are Reachable Using nc Command.md diff --git a/sources/tech/20170206 How to Check Remote Ports are Reachable Using nc Command.md b/sources/tech/20170206 How to Check Remote Ports are Reachable Using nc Command.md new file mode 100644 index 0000000000..57572c3ed7 --- /dev/null +++ b/sources/tech/20170206 How to Check Remote Ports are Reachable Using nc Command.md @@ -0,0 +1,69 @@ +How to Check Remote Ports are Reachable Using ‘nc’ Command +============================================================ + +A port is a logical entity which acts as a endpoint of communication associated with an application or process on an Linux operating system. It is useful to know which ports are open and running services on a target machine before using them. + +We can easily [list open ports in Linux][3] on a local machine using the [netstat][4] or several other Linux commands such [NMAP][5]. + +In this guide, we will show you how to determine if ports on a remote host are reachable/open using simple netcat (in short nc) command. + +netcat (or nc in short) is a powerful and easy-to-use utility that can be employed for just about anything in Linux in relation to TCP, UDP, or UNIX-domain sockets. + +``` +# yum install nc [On CentOS/RHEL] +# dnf install nc [On Fedora 22+] +$ sudo apt-get install netcat [On Debian/Ubuntu] +``` + +We can use it to: open TCP connections, listen on arbitrary TCP and UDP ports, send UDP packets, do port scanning under both IPv4 and IPv6 and beyond. + +Using netcat, you can check if a single or multiple or a range of open ports as follows. The command below will help us see if the port 22 is open on the host 192.168.56.10: + +``` +$ nc -zv 192.168.1.15 22 +``` + +In the command above, the flag: + +1. `-z` – sets nc to simply scan for listening daemons, without actually sending any data to them. +2. `-v` – enables verbose mode. + +The next command will check if ports 80, 22 and 21 are open on the remote host 192.168.5.10 (we can use the hostname as well): +nc -zv 192.168.56.10 80 22 21 + +It is also possible to specify a range of ports to be scanned:’ + +``` +$ nc -zv 192.168.56.10 20-80 +``` + +For more examples and usage of netcat command, read through our articles as follows. + +1. [Transfer Files Between Linux Servers Using netcat Command][1] +2. [Linux Network Configuration and Troubleshooting Commands][2] + +That’s all. In this article, we explained how to check if ports on a remote host are reachable/open using simple netcat commands. Make use of the comment section below to write back to us concerning about this tip. + +-------------------------------------------------------------------------------- + +译者简介： + +Aaron Kili is a Linux and F.O.S.S enthusiast, an upcoming Linux SysAdmin, web developer, and currently a content creator for TecMint who loves working with computers and strongly believes in sharing knowledge. + +-------------------------------------------------------------------------------- + +via: http://www.tecmint.com/check-remote-port-in-linux/ + +作者：[Aaron Kili][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) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]:http://www.tecmint.com/author/aaronkili/ + +[1]:http://www.tecmint.com/transfer-files-between-two-linux-machines/ +[2]:http://www.tecmint.com/linux-network-configuration-and-troubleshooting-commands/ +[3]:http://www.tecmint.com/find-open-ports-in-linux/ +[4]:http://www.tecmint.com/20-netstat-commands-for-linux-network-management/ +[5]:http://www.tecmint.com/nmap-command-examples/