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A Red Hat training course is available for Red Hat Enterprise Linux ipset Commands

The format of the ipset command is as follows:
ipset [options] command [command-options]
Where command is one of:
create | add | del | test | destroy | list | save | restore | flush | rename | swap | help | version | - 
Allowed options are:
-exist | -output [ plain | save | xml ] | -quiet | -resolve | -sorted | -name | -terse
The create command is used to create a new data structure to store a set of IP data. The add command adds new data to the set, the data added is referred to as an element of the set.
The -exist option suppresses error message if the element already exists, and it has a special role in updating a time out value. To change a time out, use the ipset add command and specify all the data for the element again, changing only the time out value as required, and using the -exist option.
The test option is for testing if the element already exists within a set.
The format of the create command is as follows:
ipset create set-name type-name [create-options]
The set-name is a suitable name chosen by the user, the type-name is the name of the data structure used to store the data comprising the set. The format of the type-name is as follows:
The allowed methods for storing data are:
 bitmap | hash | list 
The allowed data types are:
ip | net | mac | port | iface 
When adding, deleting, or testing entries in a set, the same comma separated data syntax must be used for the data that makes up one entry, or element, in the set. For example:
ipset add set-name ipaddr,portnum,ipaddr


A set cannot contain IPv4 and IPv6 addresses at the same time. When a set is created it is bound to a family, inet for IPv4 or inet6 for IPv6, and the default is inet.

Example 2.3. Create an IP Set

To create an IP set consisting of a source IP address, a port, and destination IP address, issue a command as follows:
~]# ipset create my-set hash:ip,port,ip
Once the set is created, entries can be added as follows:
~]# ipset add my-set,80,
~]# ipset add my-set,443,
The set types have the following optional parameters in common. They must be specified when the set is created in order for them to be used:
  • timeout — The value given with the create command will be the default value for the set created. If a value is given with the add command, it will be the initial non-default value for the element.

Example 2.4. List an IP Set

To list the contents of a specific IP Set, my-set, issue a command as follows:
~]# ipset list my-set
Name: my-set
Type: hash:ip,port,ip
Header: family inet hashsize 1024 maxelem 65536 
Size in memory: 8360
References: 0
Omit the set name to list all sets.

Example 2.5. Test the Elements of an IP Set

Listing the contents of large sets is time consuming. You can test for the existence of an element as follows:
~]# ipset test my-set,80,,tcp:80, is in set my-set.