nfmark target and match support

modulename: xt_mark.ko

configname: CONFIG_NETFILTER_XT_MARK

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

Netfilter mark matching allows you to match packets based on the
"nfmark" value in the packet.
The target allows you to create rules in the "mangle" table which alter
the netfilter mark (nfmark) field associated with the packet.

Prior to routing, the nfmark can influence the routing method (see
"Use netfilter MARK value as routing key") and can also be used by
other subsystems to change their behavior.

source code: