path: root/conntrack.8

.TH CONNTRACK 8 "Jun 23, 2005" "" ""

.\" Man page written by Harald Welte <laforge@netfilter.org (Jun 2005)

.SH NAME
conntrack \- administration tool for netfilter connection tracking
.SH SYNOPSIS
.BR "conntrack -L [table] [-z]"
.br
.BR "conntrack -G [table] parameters"
.br
.BR "conntrack -D [table] paramaters"
.br
.BR "conntrack -I [table] parameters"
.br
.BR "conntrack -E [table] parameters"
.br
.BR "conntrack -F [table]"
.br
.BR "conntrack -A [table] [options]"
.SH DESCRIPTION
.B conntrack
is used to search, list, inspect and maintain the netfilter connection tracking
subsystem of the Linux kernel.
.PP
Using 
.B conntrack
, you can dump a list of all (or a filtered selection of) currently tracked
connections, delete connections from the state table, and even add new ones.
.PP
In addition, you can also monitor connection tracking events, e.g. show an
event message (one line) per newly established connection.
.SH TABLES
The connection tracking subsystem maintains two internal tables:
.TP
.BR "conntrack" :
This is the default table.  It contains a list of all currently tracked
connections through the system.  If you don't use connection tracking
exemptions (NOTRACK iptables target), this means all connections that go
through the system.
.TP
.BR "expect" :
This is the table of expectations.  Connection tracking expectations are the
mechanism used to "expect" RELATED connections to existing ones.  Expectations
are generally used by "connection tracking helpers" (sometimes called
application level gateways [ALGs]) for more complex protocols such as FTP,
SIP, H.323.
.SH OPTIONS
The options recognized by 
.B conntrack
can be divided into several different groups.
.SS COMMANDS
These options specify the particular operation to perform.  Only one of them
can be specified at any given time.
.TP
.BI "-L --dump "
List connection tacking or expectation table
.TP
.BI "-G, --get "
Search for and show a particular (matching) entry in the given table.
.TP
.BI "-D, --delete "
Delete an entry from the given table.
.TP
.BI "-I, --create "
Create a new entry from the given table.
.TP
.BI "-E, --event "
Display a real-time event log.
.TP
.BI "-F, --flush "
Flush the whole given table
.TP
.BI "-A, --action "
Set an action.
.SS PARAMETERS
.TP
.BI "-z, --zero "
Atomically zero counters after reading them.  This option is only valid in
combination with the "-L, --dump" command options.
.TP
.BI "-e, --event-mask " "[ALL|NEW|RELATED|DESTROY|REFRESH|STATUS|PROTOINFO|HELPER|HELPINFO|NATINFO][,...]"
Set the bitmask of events that are to be generated by the in-kernel ctnetlink
event code.  Using this parameter, you can reduce the event messages generated
by the kernel to those types to those that you are actually interested in.
.
Please note that this is a system-wide setting, so make sure to not disable some events that other ctnetlink-using processes might need!
This option can only be used in conjunction with "-A, --action".
.TP
.BI "-m, --dump-mask " "[ALL|TUPLE|STATUS|TIMEOUT|PROTOINFO|HELPINFO|COUNTERS|MARK][,...]"
Set the bitmask of data fields that are to be sent with each message generated
by the in-kernel ctnetlink code.  Using this parameter, you can reduce the
amount of information sent by the kernel to those bits and pieces that you are
actually interested in.
Please note that this is a system-wide setting, so make sure to not disable some data fields that other ctnetlink-using processes might need!
This option can only be used in conjunction with "-A, --action".
.TP
.BI "-g, --group-mask " "[ALL|TCP|UDP|ICMP][,...]"
Set the group bitmask to those netlink groups (resembling layer 4 protocols)
that you're actually interested in. 
This option can only be used in conjunction with "-E, --event".
.SS FILTER PARAMETERS
.TP
.BI "-s, --orig-src " IP_ADDRESS
Match only entries whose source address in the original direction equals the one specified as argument.
.TP
.BI "-d, --orig-dst " IP_ADDRESS
Match only entries whose destination address in the original direction equals the one specified as argument.
.TP
.BI "-r, --reply-src " IP_ADDRESS
Match only entries whose source address in the reply direction equals the one specified as argument.
.TP
.BI "-q, --reply-dst " IP_ADDRESS
Match only entries whose destination address in the reply direction equals the one specified as argument.
.TP
.BI "-p, --proto " "PROTO "
Specify layer four (TCP, UDP, ...) protocol.
.TP
.BI "-t, --timeout " "TIMEOUT"
Specify the timeout.
.TP
.BI "-u, --status " "[EXPECTED|ASSURED|SEEN_REPLY|CONFIRMED|SNAT|DNAT|SEQ_ADJUST|UNSET][,...]"
Specify the conntrack status.
.TP
.BI "--tuple-src " IP_ADDRESS
Specify the tuple source address of an expectation.
.TP
.BI "--tuple-dst " IP_ADDRESS
Specify the tuple destination address of an expectation.
.TP
.BI "--mask-src " IP_ADDRESS
Specify the source address mask of an expectation.
.TP
.BI "--mask-dst " IP_ADDRESS
Specify the destination address mask of an expectation.
.SH DIAGNOSTICS
The exit code is 0 for correct function.  Errors which appear to be caused by
invalid command line parameters cause an exit code of 2.  Any other errors
cause an exit code of 1.
.SH BUGS
Bugs? What's this ;-)
.SH SEE ALSO
.BR iptables (8)
.br
See
.BR "http://netfilter.org/" .
.SH AUTHORS
Jay Schulist, Patrick McHardy and Harald Welte wrote the kernel-level "ctnetlink" interface that is used by the conntrack tool.
.PP
Pablo Neira wrote the conntrack tool, Harald Welte added support for conntrack based accounting counters.
.PP
Man page written by Harald Welte <laforge@netfilter.org>.