CONNTRACK

Section: (8)
Updated: May 6, 2007

NAME

conntrack - command line interface for netfilter connection tracking

SYNOPSIS

conntrack -L [table] [-z]
conntrack -G [table] parameters
conntrack -D [table] paramaters
conntrack -I [table] parameters
conntrack -E [table] parameters
conntrack -F [table]

DESCRIPTION

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 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.

In addition, you can also monitor connection tracking events, e.g. show an event message (one line) per newly established connection.

TABLES

The connection tracking subsystem maintains two internal tables:

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.
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.

OPTIONS

The options recognized by conntrack can be divided into several different groups.

COMMANDS

These options specify the particular operation to perform. Only one of them can be specified at any given time.

-L --dump: List connection tacking or expectation table
-G, --get: Search for and show a particular (matching) entry in the given table.
-D, --delete: Delete an entry from the given table.
-I, --create: Create a new entry from the given table.
-E, --event: Display a real-time event log.
-F, --flush: Flush the whole given table

PARAMETERS

-z, --zero: Atomically zero counters after reading them. This option is only valid in combination with the "-L, --dump" command options.
-o, --output [extended,xml,timestamp]: Display output in a certain format. This option is only valid in combination with the "-L, --dump", "-E, --event" and "-G, --get" command options.
-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".

FILTER PARAMETERS

-s, --orig-src IP_ADDRESS: Match only entries whose source address in the original direction equals the one specified as argument.
-d, --orig-dst IP_ADDRESS: Match only entries whose destination address in the original direction equals the one specified as argument.
-r, --reply-src IP_ADDRESS: Match only entries whose source address in the reply direction equals the one specified as argument.
-q, --reply-dst IP_ADDRESS: Match only entries whose destination address in the reply direction equals the one specified as argument.
-p, --proto PROTO: Specify layer four (TCP, UDP, ...) protocol.
-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.
-t, --timeout TIMEOUT: Specify the timeout. -m, --mark MARK Specify the conntrack mark.
-c, --secmark SECMARK: Specify the conntrack selinux security mark.
-u, --status [ASSURED|SEEN_REPLY|UNSET][,...]: Specify the conntrack status.
-n, --src-nat: Filter source NAT connections.
-g, --dst-nat: Filter destination NAT connections.
--tuple-src IP_ADDRESS: Specify the tuple source address of an expectation.
--tuple-dst IP_ADDRESS: Specify the tuple destination address of an expectation.
--mask-src IP_ADDRESS: Specify the source address mask of an expectation.
--mask-dst IP_ADDRESS: Specify the destination address mask of an expectation.

PROTOCOL FILTER PARAMETERS

TCP-specific fields:
--orig-port-src PORT: Source port in original direction
--orig-port-dst PORT: Destination port in original direction
--reply-port-src PORT: Source port in reply direction
--reply-port-dst PORT: Destination port in reply direction
--state [NONE | SYN_SENT | SYN_RECV | ESTABLISHED | FIN_WAIT | CLOSE_WAIT | LAST_ACK | TIME_WAIT | CLOSE | LISTEN]: TCP state
UDP-specific fields:
--orig-port-src PORT: Source port in original direction
--orig-port-dst PORT: Destination port in original direction
--reply-port-src PORT: Source port in reply direction
--reply-port-dst PORT: Destination port in reply direction
ICMP-specific fields:
--icmp-type TYPE: ICMP Type. Has to be specified numerically.
--icmp-code CODE: ICMP Code. Has to be specified numerically.
--icmp-id ID: ICMP Id. Has to be specified numerically (non-mandatory)

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.

EXAMPLES

conntrack -L: Dump the connection tracking table in /proc/net/ip_conntrack format
conntrack -L -o extended: Dump the connection tracking table in /proc/net/nf_conntrack format
conntrack -L -o xml: Dump the connection tracking table in XML
conntrack -L -f ipv6 -o extended: Only dump IPv6 connections in /proc/net/nf_conntrack format
conntrack -L --src-nat: Dump source NAT connections
conntrack -E -o timestamp: Show connection events together with the timestamp

BUGS

Bugs? What's this ;-)

AUTHORS

Jay Schulist, Patrick McHardy, Harald Welte and Pablo Neira wrote the kernel-level "ctnetlink" interface that is used by the conntrack tool.

Pablo Neira wrote the conntrack tool, Harald Welte added support for conntrack based accounting counters.

Man page written by Harald Welte <laforge@netfilter.org> and Pablo Neira Ayuso <pablo@netfilter.org>.

This document was created by man2html, using the manual pages.
Time: 12:38:23 GMT, December 28, 2007