path: root/conntrack.8

.TH CONNTRACK 8 "May 6, 2007" "" ""

.\" Man page written by Harald Welte <laforge@netfilter.org (Jun 2005)
.\" Maintained by Pablo Neira Ayuso <pablo@netfilter.org (May 2007)

.SH NAME
conntrack \- command line interface 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]"
.SH DESCRIPTION
.B conntrack
provides a full featured userspace interface to the netfilter connection tracking system that is intended to replace the old /proc/net/ip_conntrack interface. This tool can be used to search, list, inspect and maintain the connection tracking subsystem of the Linux kernel.
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
.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 "-o, --output [extended,xml,timestamp,id] "
Display output in a certain format. 
.TP
.BI "-e, --event-mask " "[ALL|NEW|UPDATES|DESTROY][,...]"
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.
.
This option can only be used in conjunction with "-E, --event".
.BI "-b, --buffer-size " "value (in bytes)"
Set the Netlink socket buffer size. This option is useful if the command line
tool reports ENOBUFS errors. If you do not pass this option, the default value
available at /proc/sys/net/core/rmem_default is used. The tool reports this
problem if your process is too slow to handle all the event messages or, in 
other words, if the amount of events are big enough to overrun the socket 
buffer. Note that using a big buffer reduces the chances to hit ENOBUFS, 
however, this results in more memory consumption.
.
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 "-f, --family " "PROTO"
Specify layer three (ipv4, ipv6) protocol
This option is only required in conjunction with "-L, --dump". If this option is not passed, the default layer 3 protocol will be IPv4.
.TP
.BI "-t, --timeout " "TIMEOUT"
Specify the timeout.
.BI "-m, --mark " "MARK"
Specify the conntrack mark.
.TP
.BI "-c, --secmark " "SECMARK"
Specify the conntrack selinux security mark.
.TP
.BI "-u, --status " "[ASSURED|SEEN_REPLY|UNSET][,...]"
Specify the conntrack status.
.TP
.BI "-n, --src-nat "
Filter source NAT connections. 
.TP
.BI "-g, --dst-nat "
Filter destination NAT connections. 
.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.
.SS PROTOCOL FILTER PARAMETERS
.TP
TCP-specific fields:
.TP
.BI "--sport, --orig-port-src " "PORT"
Source port in original direction
.TP
.BI "--dport, --orig-port-dst " "PORT"
Destination port in original direction
.TP
.BI "--reply-port-src " "PORT"
Source port in reply direction
.TP
.BI "--reply-port-dst " "PORT"
Destination port in reply direction
.TP
.BI "--state " "[NONE | SYN_SENT | SYN_RECV | ESTABLISHED | FIN_WAIT | CLOSE_WAIT | LAST_ACK | TIME_WAIT | CLOSE | LISTEN]"
TCP state
.TP
UDP-specific fields:
.TP
.BI "--sport, --orig-port-src " "PORT"
Source port in original direction
.TP
.BI "--dport, --orig-port-dst " "PORT"
Destination port in original direction
.TP
.BI "--reply-port-src " "PORT"
Source port in reply direction
.TP
.BI "--reply-port-dst " "PORT"
Destination port in reply direction
.TP
ICMP-specific fields:
.TP
.BI "--icmp-type " "TYPE"
ICMP Type. Has to be specified numerically.
.TP
.BI "--icmp-code " "CODE"
ICMP Code. Has to be specified numerically.
.TP
.BI "--icmp-id " "ID"
ICMP Id. Has to be specified numerically (non-mandatory)
.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 EXAMPLES
.TP
.B conntrack \-L
Show the connection tracking table in /proc/net/ip_conntrack format
.TP
.B conntrack \-L -o extended
Show the connection tracking table in /proc/net/nf_conntrack format
.TP
.B conntrack \-L \-o xml
Show the connection tracking table in XML
.TP
.B conntrack \-L -f ipv6 -o extended
Only dump IPv6 connections in /proc/net/nf_conntrack format
.TP
.B conntrack \-L --src-nat
Show source NAT connections
.TP
.B conntrack \-E \-o timestamp
Show connection events together with the timestamp
.TP
.B conntrack \-D \-s 1.2.3.4
Delete all flow whose source address is 1.2.3.4
.TP
.B conntrack \-U \-s 1.2.3.4 \-m 1
Set connmark to 1 of all the flows whose source address is 1.2.3.4
.SH BUGS
Please, report them to netfilter-devel@vger.kernel.org or file a bug in
Netfilter's bugzilla (https://bugzilla.netfilter.org).
.SH SEE ALSO
.BR iptables (8)
.br
See
.BR "http://conntrack-tools.netfilter.org"
.SH AUTHORS
Jay Schulist, Patrick McHardy, Harald Welte and Pablo Neira Ayuso wrote the kernel-level "ctnetlink" interface that is used by the conntrack tool.
.PP
Pablo Neira Ayuso wrote and maintain the conntrack tool, Harald Welte added support for conntrack based accounting counters.
.PP
Man page written by Harald Welte <laforge@netfilter.org> and Pablo Neira Ayuso <pablo@netfilter.org>.