"connlimit" match support"

modulename: xt_connlimit.ko

configname: CONFIG_NETFILTER_XT_MATCH_CONNLIMIT

Linux Kernel Configuration
└─>Networking
└─>Networking options
└─>Network packet filtering framework (Netfilter)
└─>Core Netfilter Configuration
└─>"connlimit" match support"
In linux kernel since version 2.6.23 (release Date: 2007-10-09)  
This match allows you to match against the number of parallel
connections to a server per client IP address (or address block).

source code: