Ubuntu Manpage: conntrack - command line interface for netfilter connection tracking

NAME

       conntrack - command line interface for netfilter connection tracking

SYNOPSIS

       conntrack -L [table] [options] [-z]
       conntrack -G [table] parameters
       conntrack -D [table] parameters
       conntrack -I [table] parameters
       conntrack -A [table] parameters
       conntrack -U [table] parameters
       conntrack -E [table] [options]
       conntrack -F [table]
       conntrack -C [table]
       conntrack -S
       conntrack -R file

DESCRIPTION

       The  conntrack  utility  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 several 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 or H.323.

dying: This table shows the conntrack entries, that have expired and that have been
destroyed by the connection tracking system itself, or via the conntrack utility.

unconfirmed:
This table shows new entries, that are not yet inserted into the conntrack table.
These entries are attached to packets that are traversing the stack, but did not
reach the confirmation point at the postrouting hook.

The tables "dying" and "unconfirmed" are basically only useful for debugging
purposes. Under normal operation, it is hard to see entries in any of them. There
are corner cases, where it is valid to see entries in the unconfirmed table, eg.
when packets that are enqueued via nfqueue, and the dying table, eg. when
conntrackd(8) runs in event reliable mode.

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 tracking 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, it fails if it already exists.

-A, --add
Add a new entry from the given table.

-U, --update
Update an entry from the given table.

-E, --event
Display a real-time event log.

-F, --flush
Flush the whole given table

-C, --count
Show the table counter.

-S, --stats
Show the in-kernel connection tracking system statistics.

-R, --load-file
Load entries from a given file. To read from stdin, "-" should be specified.

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,save,timestamp,id,ktimestamp,labels]
Display output in a certain format. With the extended output option, this tool
displays the layer 3 information. With ktimestamp, it displays the in-kernel
timestamp available since 2.6.38 (you can enable it via the sysctl(8) key
net.netfilter.nf_conntrack_timestamp). The labels output option tells conntrack to
show the names of connection tracking labels that might be present. The userspace
output option tells if the event has been triggered by a process.

-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 the types that you are actually interested in. This option can only be
used in conjunction with "-E, --event".

-b, --buffer-size value
Set the Netlink socket buffer size in bytes. This option is useful if the command
line tool reports ENOBUFS errors. If you do not pass this option, the default value
available at sysctl(8) key 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 is 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".

FILTER PARAMETERS
-s, --src, --orig-src IP_ADDRESS
Match only entries whose source address in the original direction equals the one
specified as argument. Implies "--mask-src" when CIDR notation is used.

-d, --dst, --orig-dst IP_ADDRESS
Match only entries whose destination address in the original direction equals the
one specified as argument. Implies "--mask-dst" when CIDR notation is used.

-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[/MASK]
Specify the conntrack mark. Optionally, a mask value can be specified. In
"--update" mode, this mask specifies the bits that should be zeroed before XORing
the MARK value into the ctmark. Otherwise, the mask is logically ANDed with the
existing mark before the comparison. In "--create" mode, the mask is ignored.

-l, --label LABEL
Specify a conntrack label. This option is only available in conjunction with "-L,
--dump", "-E, --event", "-U --update" or "-D --delete". Match entries whose labels
include those specified as arguments. Use multiple -l options to specify multiple
labels that need to be set.

--label-add LABEL
Specify the conntrack label to add to the selected conntracks. This option is only
available in conjunction with "-I, --create", "-A, --add" or "-U, --update".

--label-del [LABEL]
Specify the conntrack label to delete from the selected conntracks. If no label is
given, all labels are deleted. This option is only available in conjunction with
"-U, --update".

-c, --secmark SECMARK
Specify the conntrack selinux security mark.

-n, --src-nat
Filter source NAT connections.

-g, --dst-nat
Filter destination NAT connections.

-j, --any-nat
Filter any NAT connections.

-w, --zone
Filter by conntrack zone. See iptables CT target for more information.

--orig-zone
Filter by conntrack zone in original direction. See iptables CT target for more
information.

--reply-zone
Filter by conntrack zone in reply direction. See iptables CT target for more
information.

--tuple-src IP_ADDRESS
Specify the tuple source address of an expectation. Implies "--mask-src" when CIDR
notation is used.

--tuple-dst IP_ADDRESS
Specify the tuple destination address of an expectation. Implies "--mask-dst" when
CIDR notation is used.

--mask-src IP_ADDRESS
Specify the source address mask. For conntracks this option is only available in
conjunction with "-L, --dump", "-E, --event", "-U --update" or "-D --delete". For
expectations this option is only available in conjunction with "-I, --create".

--mask-dst IP_ADDRESS
Specify the destination address mask. Same limitations as for "--mask-src".

PROTOCOL FILTER PARAMETERS
TCP-specific fields:

--sport, --orig-port-src PORT
Source port in original direction

--dport, --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 state
TCP state, one of NONE, SYN_SENT, SYN_RECV, ESTABLISHED, FIN_WAIT, CLOSE_WAIT,
LAST_ACK, TIME_WAIT, CLOSE or LISTEN.

UDP-specific fields:

--sport, --orig-port-src PORT
Source port in original direction

--dport, --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)

UDPlite-specific fields:

--sport, --orig-port-src PORT
Source port in original direction

--dport, --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

SCTP-specific fields:

--sport, --orig-port-src PORT
Source port in original direction

--dport, --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 state
SCTP state, one of NONE, CLOSED, COOKIE_WAIT, COOKIE_ECHOED, ESTABLISHED,
SHUTDOWN_SENT, SHUTDOWN_RECD, SHUTDOWN_ACK_SENT.

--orig-vtag value
Verification tag (32-bits value) in the original direction

--reply-vtag value
Verification tag (32-bits value) in the reply direction

DCCP-specific fields (needs Linux >= 2.6.30):

--sport, --orig-port-src PORT
Source port in original direction

--dport, --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 state
DCCP state, one of NONE, REQUEST, RESPOND, PARTOPEN, OPEN, CLOSEREQ, CLOSING,
TIMEWAIT.

--role [client|server]
Role that the original conntrack tuple is tracking

GRE-specific fields:

--srckey, --orig-key-src KEY
Source key in original direction (in hexadecimal or decimal)

--dstkey, --orig-key-dst KEY
Destination key in original direction (in hexadecimal or decimal)

--reply-key-src KEY
Source key in reply direction (in hexadecimal or decimal)

--reply-key-dst KEY
Destination key in reply direction (in hexadecimal or decimal)

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
              Show the connection tracking table in /proc/net/ip_conntrack format

       conntrack -L -o extended
              Show   the   connection  tracking  table  in  /proc/net/nf_conntrack  format,  with
              additional information.

       conntrack -L -o xml
              Show the connection tracking table in XML

       conntrack -L -o save
              Show the connection tracking table in conntrack syntax format

       conntrack -L -f ipv6 -o extended
              Only dump  IPv6  connections  in  /proc/net/nf_conntrack  format,  with  additional
              information.

       conntrack -L --src-nat
              Show source NAT connections

       conntrack -E -o timestamp
              Show connection events together with the timestamp

       conntrack -D -s 1.2.3.4
              Delete all flows whose source address is 1.2.3.4

       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

       conntrack -L -w 11 -o save | sed s/-w 11/-w 12/g | conntrack --load-file -
              Copy all entries from ct zone 11 to ct zone 12

BUGS

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

AUTHORS

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

       Pablo  Neira  Ayuso wrote and maintains 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>.

                                           Aug 9, 2019                               CONNTRACK(8)

NAME

SYNOPSIS

DESCRIPTION

TABLES

OPTIONS

DIAGNOSTICS

EXAMPLES

BUGS

SEE ALSO

AUTHORS