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How to block unwanted IP addresses on Linux efficiently
================================================================================
You may want to block IP addresses on your Linux box under various circumstances. For example, as an end user you may want to protect yourself from known spyware or tracker IP addresses. Or when you are running P2P software, you may want to filter out connections from networks associated with anti-P2P activity. If you are a sysadmin, you may want to ban access from spam IP addresses to your production mail server. Or you may wish to block web server access from certain countries for some reason. In many cases, however, your IP address block list can grow quickly to tens of thousands of IP addresses or IP address blocks. How can you deal with it?
### Problems of Netfilter/IPtables ###
In Linux, banning an IP address can be done very easily with netfilter/iptables framework:
$ sudo iptables -A INPUT -s 1.1.1.1 -p TCP -j DROP
If you want to ban a whole IP address block, you can also do it as easily:
$ sudo iptables -A INPUT -s 1.1.2.0/24 -p TCP -j DROP
However, what if you have 1,000 independent IP addresses with no common CIDR prefix that you want to ban? You would have 1,000 iptables rules! Clearly this does not scale.
$ sudo iptables -A INPUT -s 1.1.1.1 -p TCP -j DROP
$ sudo iptables -A INPUT -s 2.2.2.2 -p TCP -j DROP
$ sudo iptables -A INPUT -s 3.3.3.3 -p TCP -j DROP
. . . .
### What are IP Sets? ###
That is when [IP sets][1] come in handy. IP sets are a kernel feature which allows multiple (independent) IP addresses, MAC addresses or even port numbers to be encoded and stored efficiently within bitmap/hash kernel data structures. Once an IP set is created, you can create an iptables rule which matches against the set.
You should immediately see the benefit of using IP sets, which is that you can match against multiple IP addresses in an IP set by using a single iptables rule! You can construct IP sets using combinations of multiple IP addresses and port numbers, and can dynamically update iptables rules with IP sets without any performance impact.
### Install IPset Tool on Linux ###
To create and manage IP sets, you need to use a userspace tool called ipset.
To install ipset on Debian, Ubuntu or Linux Mint:
$ sudo apt-get install ipset
To install ipset on Fedora or CentOS/RHEL 7:
$ sudo yum install ipset
### Ban IP Addresses using IPset Command ###
Let me walk you through on how to use ipset command using simple examples.
First, let's create a new IP set named banthis (name can be arbitrary):
$ sudo ipset create banthis hash:net
The second argument (hash:net) in the above is required, and represents the type of a set being created. There are [multiple types][2] of IP sets. An IP set of hash:net type uses a hash to store multiple CIDR blocks. If you want to store individual IP addresses in a set, you can use hash:ip type instead.
Once you have created an IP set, you can check up on the set with:
$ sudo ipset list
![](https://farm8.staticflickr.com/7483/15380353464_825dbc45c2_z.jpg)
This shows a list of available IP sets, along with detailed information of each set including set membership. By default, each IP set can contain up to 65536 elements (CIDR blocks in this case). You can increase this limit by appending "maxelem N" option.
$ sudo ipset create banthis hash:net maxelem 1000000
Now let's add IP address blocks to the set:
$ sudo ipset add banthis 1.1.1.1/32
$ sudo ipset add banthis 1.1.2.0/24
$ sudo ipset add banthis 1.1.3.0/24
$ sudo ipset add banthis 1.1.4.10/24
You will see that the set membership has been changed.
$ sudo ipset list
![](https://farm8.staticflickr.com/7518/15380353474_4d6b9dbf63_z.jpg)
Now it is time to create an iptables rule using this IP set. The key here is to use "-m set --match-set <name>" option.
Let's create an iptables rule which prevents all those IP blocks in the set from accessing a web server at port 80. This can be achieved by:
$ sudo iptables -I INPUT -m set --match-set banthis src -p tcp --destination-port 80 -j DROP
If you want, you can save a specific IP set to a file, and then later restore it from the file:
$ sudo ipset save banthis -f banthis.txt
$ sudo ipset destroy banthis
$ sudo ipset restore -f banthis.txt
In the above, I tried removing an existing IP set using destroy option to see if I can restore the IP set.
### Automate IP Address Banning ###
By now you should see how powerful the concept of IP sets is. Still maintaining a up-to-date IP blacklist can be a cumbersome and time-consuming process. In fact, there are free or paid services out there which maintain these IP blacklists for you. As a bonus, let's see how we can automatically translate available IP blacklists into IP sets.
Let me grab free IP lists from [iblocklist.com][3] which publish various IP block lists for free or for a fee. Free versions are available in P2P format.
Here I am going to use an open-source python tool called iblocklist2ipset which converts P2P versions of iblocklist into IP sets.
First, you need to have pip installed (see [this guideline][4] to install pip).
Then install iblocklist2ipset as follows.
$ sudo pip install iblocklist2ipset
On some distros like Fedora, you may need to run:
$ sudo python-pip install iblocklist2ipset
Now go to [iblocklist.com][5], and grab any P2P list URL (e.g., "level1" list).
![](https://farm8.staticflickr.com/7523/15976824856_80632f35e1_z.jpg)
Then paste the URL into the following command.
$ iblocklist2ipset generate \
--ipset banthis "http://list.iblocklist.com/?list=ydxerpxkpcfqjaybcssw&fileformat=p2p&archiveformat=gz" \
> banthis.txt
After you run the above command, you will get a file named bandthis.txt created. If you check its content, you will see something like:
create banthis hash:net family inet hashsize 131072 maxelem 237302
add banthis 1.2.4.0/24
add banthis 1.2.8.0/24
add banthis 1.9.75.8/32
add banthis 1.9.96.105/32
add banthis 1.9.102.251/32
add banthis 1.9.189.65/32
add banthis 1.16.0.0/14
You can simply load this file with ipset command:
$ sudo ipset restore -f banthis.txt
Now check the automatically created IP set with:
$ sudo ipset list banthis
As of this writing, the "level1" block list contains more than 237,000 IP address blocks. You will see that that many IP address blocks have been added to the IP set.
Finally, go ahead and create a single iptables rule to block them all!
### Summary ###
In this tutorial, I demonstrated how you can block unwanted IP addresses using a powerful tool called ipset. Combine that with a third-party tool like iblocklist2ipset, and you can easily streamline the process of maintaining your IP block list. For those of you who are curious about the speed improvement of ipset, the figure below shows the benchmark result comparing iptables without and with ipset (credit to [daemonkeeper.net][6]).
![](https://farm8.staticflickr.com/7575/15815220998_e1935c94c0_z.jpg)
Tell me how much you like it. :-)
--------------------------------------------------------------------------------
via: http://xmodulo.com/block-unwanted-ip-addresses-linux.html
作者:[Dan Nanni][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/nanni
[1]:http://ipset.netfilter.org/
[2]:http://ipset.netfilter.org/features.html
[3]:https://www.iblocklist.com/lists.php
[4]:http://ask.xmodulo.com/install-pip-linux.html
[5]:https://www.iblocklist.com/lists.php
[6]:http://daemonkeeper.net/781/mass-blocking-ip-addresses-with-ipset/

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如何在Linux有效地屏蔽不需要的IP
================================================================================
你可能需要在Linux的不同的环境下屏蔽IP地址。比如作为一个终端用户你可能想要免受间谍软件或者IP追踪的困扰。或者当你在运行P2P软件时。你可能想要过滤反P2P活动的网络链接。如果你是一名系统管理员你可能想要禁止垃圾IP地址访问你们的生产邮件服务器。或者你因一些原因想要禁止某些国家访问web服务。在许多情况下然而你的IP地址屏蔽列表可能会很快地增长到几万的IP。该如何处理这个
### Netfilter/IPtables 的问题 ###
在Linux中可以很简单地用netfilter/iptables框架禁止IP地址
$ sudo iptables -A INPUT -s 1.1.1.1 -p TCP -j DROP
如果你想要完全屏蔽一个IP地址你可以用下面的命令很简单地做到
$ sudo iptables -A INPUT -s 1.1.2.0/24 -p TCP -j DROP
然而当你有1000个独立IP地址且不带CIDR无类别域间路由前缀你该怎么做你要有1000条iptable规则这显然无法扩展。
$ sudo iptables -A INPUT -s 1.1.1.1 -p TCP -j DROP
$ sudo iptables -A INPUT -s 2.2.2.2 -p TCP -j DROP
$ sudo iptables -A INPUT -s 3.3.3.3 -p TCP -j DROP
. . . .
### 什么是IP集? ###
这时候就是[IP集][1]登场了。IP集是一个内核特性它允许多个独立IP地址、MAC地址或者甚至是端口号编码并有效地存储在位图/哈希内核数据结构中。一旦IP集创建之后你可以创建一条iptable规则来匹配这个集合。
你应该马上看见IP集合的好处了它可以让你用一条iptable规则匹配多个ip地址你可以用多个IP地址和端口号的方式来构造IP集并且可以动态地更新规则而没有请能影响。
### 在Linux中安装IPset工具 ###
为了创建和管理IP集你需要使用成为ipset的用户空间工具。
要在Debian、Ubuntu或者Linux Mint上安装
$ sudo apt-get install ipset
Fedora或者CentOS/RHEL 7上安装
$ sudo yum install ipset
### 使用IPset命令禁止IP ###
让我通过简单的示例告诉你该如何使用ipset命令。
首先让我们创建一条新的IP集名为banthis名字任意
$ sudo ipset create banthis hash:net
第二个参数(hash:net)是必须的代表的是集合的类型。IP集有[多个类型][2]。hash:net类型的IP集使用哈希来存储多个CIDR块。如果你想要在一个集合中存储独立的IP地址你可以使用hash:ip类型。
一旦创建了一个IP集之后你可以用下面的命令来检查
$ sudo ipset list
![](https://farm8.staticflickr.com/7483/15380353464_825dbc45c2_z.jpg)
这显示了一个可用的IP集合列表并有包含了集合成员的详细信息。默认上每个IP集合可以包含65536个元素这里是CIDR块。你可以通过追加"maxelem N"选项来增加限制。
$ sudo ipset create banthis hash:net maxelem 1000000
现在让我们来增加IP块到这个集合中
$ sudo ipset add banthis 1.1.1.1/32
$ sudo ipset add banthis 1.1.2.0/24
$ sudo ipset add banthis 1.1.3.0/24
$ sudo ipset add banthis 1.1.4.10/24
你会看到集合成员已经改变了。
$ sudo ipset list
![](https://farm8.staticflickr.com/7518/15380353474_4d6b9dbf63_z.jpg)
现在是时候去创建一个使用IP集的iptable规则了。这里的关键是使用"-m set --match-set <name>"选项。
现在让我们创建一条让之前那些IP块不能通过80端口访问web服务的iptable规则。可以通过下面的命令
$ sudo iptables -I INPUT -m set --match-set banthis src -p tcp --destination-port 80 -j DROP
如果你想你可以保存特定的IP集到一个文件中以后可以从文件中还原
$ sudo ipset save banthis -f banthis.txt
$ sudo ipset destroy banthis
$ sudo ipset restore -f banthis.txt
上面的命令中我使用了destory选项来删除一个已有的IP集来见证我可以还原它。
### 自动IP地址禁用 ###
现在你应该看到了IP集合的强大了。维护IP黑名单是一件繁琐和费时的工作。实际上有很多免费或者收费的服务可以来帮你完成这个。一个额外的好处是让我们看看如何自动将IP黑名单家到IP集中。
首先让我们从[iblocklist.com][3]抓取免费的黑名单这个网站u有不同的免费和收费的名单。免费的版本是P2P格式。
接下来我要使用一个名为iblocklist2ipset的开源Python工具来将P2P格式的黑名单转化成IP集。
首先你需要安装了pip参考[这个指导][4]来安装pip
使用的下面命令安装iblocklist2ipset。
$ sudo pip install iblocklist2ipset
在一些发行版如Fedora你可能需要运行
$ sudo python-pip install iblocklist2ipset
现在到[iblocklist.com][5]抓取任何一个P2P列表的URL比如"level1"列表)。
![](https://farm8.staticflickr.com/7523/15976824856_80632f35e1_z.jpg)
粘帖URL到下面的命令中。
$ iblocklist2ipset generate \
--ipset banthis "http://list.iblocklist.com/?list=ydxerpxkpcfqjaybcssw&fileformat=p2p&archiveformat=gz" \
> banthis.txt
上面的命令运行之后你会得到一个名为banthis.txt的文件。如果查看它的内容你会看到像这些
create banthis hash:net family inet hashsize 131072 maxelem 237302
add banthis 1.2.4.0/24
add banthis 1.2.8.0/24
add banthis 1.9.75.8/32
add banthis 1.9.96.105/32
add banthis 1.9.102.251/32
add banthis 1.9.189.65/32
add banthis 1.16.0.0/14
你可以用下面的ipset命令来加载这个文件
$ sudo ipset restore -f banthis.txt
现在可以查看自动创建的IP集
$ sudo ipset list banthis
在写这篇文章时候“level1”类表包含了237,000个屏蔽的IP列表。你可以看到很多IP地址已经加入到IP集中了。
最后创建一条iptable命令来屏蔽它们
### 总结 ###
这篇文章中我描述了你该如何用强大的ipset来·屏蔽不想要的IP地址。同时结合了第三方工具iblocklist2ipset这样你就可以流畅地维护你的IP屏蔽列表了。对于那些对于ipset的速度提升好奇的人来说下图显示了iptables在使用和不使用ipset的基准测试结果。
![](https://farm8.staticflickr.com/7575/15815220998_e1935c94c0_z.jpg)
告诉我你多么喜欢这个。:-)
--------------------------------------------------------------------------------
via: http://xmodulo.com/block-unwanted-ip-addresses-linux.html
作者:[Dan Nanni][a]
译者:[geekpi](https://github.com/geekpi)
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/nanni
[1]:http://ipset.netfilter.org/
[2]:http://ipset.netfilter.org/features.html
[3]:https://www.iblocklist.com/lists.php
[4]:http://ask.xmodulo.com/install-pip-linux.html
[5]:https://www.iblocklist.com/lists.php
[6]:http://daemonkeeper.net/781/mass-blocking-ip-addresses-with-ipset/