NAME¶

nfct - command line tool to configure with the connection tracking system

SYNOPSIS¶

nfct command subsystem [parameters]

DESCRIPTION¶

nfct is the command line tool that allows to configure the Connection Tracking System.

COMMANDS¶

list

List the existing objects.

add

Add new object.

delete

Delete an object.

get

Get an existing object.

flush

Flush the accounting object table.

disable

This command is for the helper subsystem. It allows you to disable enqueueing packets to userspace for helper inspection.

default-set

This command is for the timeout subsystem. It allows you to set default protocol timeouts.

default-get

This command is for the timeout subsystem. It allows you to get the default protocol timeouts.

SUBSYS¶

By the time this manpage has been written, the supported subsystems are timeout and helper.

timeout

The timeout subsystem allows you to define fine-grain timeout policies.

helper

The helper subsystem allows you to configure userspace helpers.

version

Displays the version information.

help

Displays the help message.

EXAMPLE¶

nfct add timeout test-tcp inet tcp established 100 close 10 close_wait 10

This creates a timeout policy for tcp using 100 seconds for the ESTABLISHED state, 10 seconds for CLOSE state and 10 seconds for the CLOSE_WAIT state.

Then, you can attach the timeout policy with the iptables CT target:

iptables -I PREROUTING -t raw -p tcp -j CT --timeout test-tcp

iptables -I OUTPUT -t raw -p tcp -j CT --timeout test-tcp

You can test that the timeout policy with:

conntrack -E -p tcp

It should display:

[UPDATE] tcp 6 100 ESTABLISHED src=192.168.39.100 dst=57.126.1.20 sport=56463 dport=80 src=57.126.1.20 dst=192.168.39.100 sport=80 dport=56463 [ASSURED]

SEE ALSO¶

iptables(8),conntrack(8)

BUGS¶

Please, report them to netfilter-devel@vger.kernel.org or file a bug in Netfilter's bugzilla (https://bugzilla.netfilter.org).

AUTHORS¶

Pablo Neira Ayuso wrote and maintains the nfct tool.

Man page written by Pablo Neira Ayuso <pablo@netfilter.org>.