ctmark target and match support

modulename: xt_connmark.ko

configname: CONFIG_NETFILTER_XT_CONNMARK

Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>Network packet filtering framework (Netfilter)
└─>Core Netfilter Configuration
└─>ctmark target and match support
In linux kernel since version 2.6.35 (release Date: 2010-08-01)  
This option adds the "CONNMARK" target and "connmark" match.

Netfilter allows you to store a mark value per connection (a.k.a.
ctmark), similarly to the packet mark (nfmark). Using this
target and match, you can set and match on this mark.

source code: