CentOS / RHEL: Install ipset Administration Tool For IP Sets and IPTables

How do I install the ipset extension to Netfilter/iptables on Red Hat Enterprise Linux / CentOS Linux v6.x?

IP sets are a framework inside the Linux 2.4.x and 2.6.x kernel, which can be administered by the ipset utility. Depending on the type, currently an IP set may store IP addresses, (TCP/UDP) port numbers or IP addresses with MAC addresses in a way, which ensures lightning speed when matching an entry against a set. If you want to

  1. Store multiple IP addresses or port numbers and match against the collection by iptables at one swoop;
  2. Dynamically update iptables rules against IP addresses or ports without performance penalty;
  3. Express complex IP address and ports based rulesets with one single iptables rule and benefit from the speed of IP sets then ipset may be the proper tool for you.


First turn on EPEL repo and type the following yum command:
# yum install ipset
Sample outputs:

Loaded plugins: auto-update-debuginfo, protectbase, rhnplugin
0 packages excluded due to repository protections
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package ipset.x86_64 0:6.11-1.el6 will be installed
--> Processing Dependency: libmnl.so.0(LIBMNL_1.0)(64bit) for package: ipset-6.11-1.el6.x86_64
--> Processing Dependency: libmnl.so.0()(64bit) for package: ipset-6.11-1.el6.x86_64
--> Running transaction check
---> Package libmnl.x86_64 0:1.0.3-4.el6 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
 Package       Arch          Version             Repository                   Size
 ipset         x86_64        6.11-1.el6          rhel-x86_64-server-6         61 k
Installing for dependencies:
 libmnl        x86_64        1.0.3-4.el6         epel                         22 k
Transaction Summary
Install       2 Package(s)
Total download size: 82 k
Installed size: 46 k
Is this ok [y/N]: y
Downloading Packages:
(1/2): ipset-6.11-1.el6.x86_64.rpm                          |  61 kB     00:00     
(2/2): libmnl-1.0.3-4.el6.x86_64.rpm                        |  22 kB     00:00     
Total                                              172 kB/s |  82 kB     00:00     
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing : libmnl-1.0.3-4.el6.x86_64                                       1/2 
  Installing : ipset-6.11-1.el6.x86_64                                         2/2 
  Verifying  : libmnl-1.0.3-4.el6.x86_64                                       1/2 
  Verifying  : ipset-6.11-1.el6.x86_64                                         2/2 
  ipset.x86_64 0:6.11-1.el6                                                        
Dependency Installed:
  libmnl.x86_64 0:1.0.3-4.el6                                                      


Type the following commands:

 ## create ip set called badips (-N)    ##
## Uses a hash to  store IP  host  addresses or  network ## 
## addresses. Zero valued IP address cannot be stored    ##
## in a iphashtype of set. ##
ipset -N badips iphash
## add IP address ##
ipset -A badips
ipset -A badips
## drop all ip address stored in ipset called badips ##
iptables -A INPUT -m set --set badips src -j DROP

The recommended syntax is as follows:
# ipset create myblacklist hash:ip hashsize 4096
# iptables -A INPUT -m set --set myblacklist src -j DROP

Now, you can add IP address as follows:
# ipset add myblacklist
# ipset add myblacklist
# ipset add myblacklist

ipset has command has many more options. See man page for more details:
# man ipsets

Posted by: SXI ADMIN

The author is the creator of SXI LLC and a seasoned sysadmin, DevOps engineer, and a trainer for the Linux operating system/Unix shell scripting. Get the latest tutorials on SysAdmin, Linux/Unix and open source topics via RSS/XML feed or weekly email newsletter.