.TH CONNTRACKD 8 "Oct 21, 2008" "" ""
.\" Man page written by Pablo Neira Ayuso <firstname.lastname@example.org> (Dec 2007)
conntrackd \- netfilter connection tracking user-space daemon
.BR "conntrackd [options]"
is the user-space daemon for the netfilter connection tracking system. This daemon synchronizes connection tracking states between several replica firewalls. Thus,
can be used to deploy highly available stateful firewalls. The daemon supports Primary-Backup and Multiprimary setups. The daemon can also be used as statistics collector.
The options recognized by
can be divided into several different groups.
These options specify the particular operation mode in which conntrackd runs. Only one of them can be specified at any given time.
.BI "-d "
Run conntrackd in daemon mode.
.SS CLIENT COMMANDS
can be used in client mode to request several information and operations to a running daemon
.BI "-i "
Dump the internal cache, i.e. show local states
.BI "-e "
Dump the external cache, i.e. show foreign states
.BI "-x "
Display output in XML format. This option is only valid in combination
with "-i" and "-e" parameters.
.BI "-f "
Flush the internal and the external cache
.BI "-k "
Kill the daemon
.BI "-s "
.BI "-R "
Force a resync against the kernel connection tracking table
.BI "-t "
Reset the in-kernel timers (See PurgeTimeout clause)
The exit code is 0 for correct function. Errors cause an exit code of 1.
The following example are illustrative, for a real use in a firewall fail-over,
check the primary-backup.sh script that comes with the sources.
.B conntrackd \-d
Runs conntrackd in daemon and synchronization mode
.B conntrackd \-i
Dumps the states held in the internal cache, i.e. those handled by this firewall
.B conntrackd \-e
Dumps the states held in the external cache, i.e. those handled by other replica firewalls
.B conntrackd \-c
Commits the external cache into the kernel connection tracking system. This is used to inject the state so that the connections can be recovered during the failover.
This daemon requires a Linux kernel version >= 2.6.18. TCP window tracking support requires >= 2.6.22, otherwise you have to disable it. Helpers are fully supported since >= 2.6.25, however, if you use any previous version, depending on the protocol helper and your setup (e.g. if you setup performs NAT sequence adjustments or not), your help connection may be successfully recovered.
There are several unsupported stateful iptables matches such as recent, connbytes and the quota matches which gather internal information to operate. Since that information does not belong to the domain of the connection tracking system, connections affected by those matches may not be fully recovered during the takeover.
The daemon requires a Linux kernel version >= 2.6.26 to support kernel-space event filtering. Otherwise, all the event filtering is done in userspace with the corresponding extra overhead. If you are not using the Filter clause in the configuration file, ignore this notice.
.SH SEE ALSO
.BR conntrack (8), iptables (8)
Please, report them to email@example.com or file a bug in
Netfilter's bugzilla (https://bugzilla.netfilter.org).
Pablo Neira Ayuso wrote and maintains the conntrackd tool
Please send bug reports to <firstname.lastname@example.org>. Subscription is required.
Man page written by Pablo Neira Ayuso <email@example.com>.