Ubuntu Manpage: conntrack - shorewall6 conntrack file

NAME

       conntrack - shorewall6 conntrack file

SYNOPSIS


       /etc/shorewall6/conntrack

DESCRIPTION

The original intent of the notrack file was to exempt certain traffic from Netfilter connection tracking.
Traffic matching entries in the file were not to be tracked.

The role of the file was expanded in Shorewall 4.4.27 to include all rules that can be added in the
Netfilter raw table. In 4.5.7, the file's name was changed to conntrack.

The file supports two different column layouts: FORMAT 1, FORMAT 2, and FORMAT 3, FORMAT 1 being the
default. The three differ as follows:

• in FORMAT 2 and 3, there is an additional leading ACTION column.

• in FORMAT 3, the SOURCE column accepts no zone name; rather the ACTION column allows a SUFFIX that
determines the chain(s) that the generated rule will be added to.

When an entry in the following form is encountered, the format of the following entries are assumed to be
of the specified format.
?FORMAT
format

where format is either 1,2 or 3.

Format 3 was introduced in Shorewall 4.5.10.

Comments may be attached to Netfilter rules generated from entries in this file through the use of
?COMMENT lines. These lines begin with ?COMMENT; the remainder of the line is treated as a comment which
is attached to subsequent rules until another ?COMMENT line is found or until the end of the file is
reached. To stop adding comments to rules, use a line with only ?COMMENT.

The columns in the file are as follows (where the column name is followed by a different name in
parentheses, the different name is used in the alternate specification syntax).

ACTION -
{NOTRACK|CT:helper:name[(arg=val[,...])|CT:ctevents:event[,...]|CT:expevents:new|notrack|DROP|LOG|NFLOG(nflog-parameters)|IP6TABLES(target)}[:log-level[:log-tag]][:chain-designator]
This column is only present when FORMAT >= 2. Values other than NOTRACK require CT Targetsupport in
your iptables and kernel.

• NOTRACK or CT:notrack

Disables connection tracking for this packet. If a log-level is specified, the packet will also
be logged at that level.

• helper:name

Attach the helper identified by the name to this connection. This is more flexible than loading
the conntrack helper with preset ports. If a log-level is specified, the packet will also be
logged at that level.

At this writing, the available helpers are:

amanda
Requires that the amanda netfilter helper is present.

ftp
Requires that the FTP netfilter helper is present.

irc
Requires that the IRC netfilter helper is present.

netbios-ns
Requires that the netbios_ns (sic) helper is present.

RAS and Q.931
These require that the H323 netfilter helper is present.

pptp
Requires that the pptp netfilter helper is present.

sane
Requires that the SANE netfilter helper is present.

sip
Requires that the SIP netfilter helper is present.

snmp
Requires that the SNMP netfilter helper is present.

tftp
Requires that the TFTP netfilter helper is present.

May be followed by an option list of arg=val pairs in parentheses:

• ctevents=event[,...]

Only generate the specified conntrack events for this connection. Possible event types are:
new, related, destroy, reply, assured, protoinfo, helper, mark (this is connection mark, not
packet mark), natseqinfo, and secmark. If more than one event is listed, the event list must
be enclosed in parentheses (e.g., ctevents=(new,related)).

• expevents=new

Only generate new expectation events for this connection.

• ctevents:event[,...]

Added in Shorewall 4.6.10. Only generate the specified conntrack events for this connection.
Possible event types are: new, related, destroy, reply, assured, protoinfo, helper, mark (this is
connection mark, not packet mark), natseqinfo, and secmark.

• expevents=new

Added in Shorewall 4.6.10. Only generate new expectation events for this connection.

• DROP

Added in Shorewall 4.5.10. Silently discard the packet. If a log-level is specified, the packet
will also be logged at that level.

• IP6TABLES(target)

Added in Shorewall 4.6.0. Allows you to specify any iptables target with target options (e.g.,
"IP6TABLES(AUDIT --type drop)"). If the target is not one recognized by Shorewall, the following
error message will be issued:
ERROR: Unknown target
(target)
This error message may be eliminated by adding target as a builtin action in
shorewall6-actions(5)[1].

• LOG

Added in Shoreawll 4.6.0. Logs the packet using the specified log-level and log-tag (if any). If
no log-level is specified, then 'info' is assumed.

• NFLOG

Added in Shoreawll 4.6.0. Queues the packet to a backend logging daemon using the NFLOG netfilter
target with the specified nflog-parameters.

When FORMAT = 1, this column is not present and the rule is processed as if NOTRACK had been entered
in this column.

Beginning with Shorewall 4.5.10, when FORMAT = 3, this column can end with a colon followed by a
chain-designator. The chain-designator can be one of the following:

P
The rule is added to the raw table PREROUTING chain. This is the default if no chain-designator
is present.

O
The rule is added to the raw table OUTPUT chain.

PO or OP
The rule is added to the raw table PREROUTING and OUTPUT chains.

SOURCE (formats 1 and 2) – zone[:interface][:address-list]
where zone is the name of a zone, interface is an interface to that zone, and address-list is a
comma-separated list of addresses (may contain exclusion - see shorewall6-exclusion[2] (5)).

Beginning with Shorewall 4.5.7, all can be used as the zone name to mean all zones.

Beginning with Shorewall 4.5.10, all- can be used as the zone name to mean all off-firewall zones.

SOURCE (format 3) – {-|interface[:address-list]|address-list}
Where interface is an interface to that zone, and address-list is a comma-separated list of addresses
(may contain exclusion - see shorewall6-exclusion[2] (5)).

COMMENT is only allowed in format 1; the remainder of the line is treated as a comment that will be
associated with the generated rule(s).

DEST – {-|interface[:address-list]|address-list}
where address-list is a comma-separated list of addresses (may contain exclusion - see
shorewall6-exclusion[2] (5)).

PROTO – protocol-name-or-number[,...]
A protocol name from /etc/protocols or a protocol number.

Beginning with Shorewall 4.5.12, this column can accept a comma-separated list of protocols.

DPORT - {-|port-number/service-name-list|+ipset}
A comma-separated list of port numbers and/or service names from /etc/services. May also include port
ranges of the form low-port:high-port if your kernel and iptables include port range support.

Beginning with Shorewall 4.6.0, an ipset name can be specified in this column. This is intended to be
used with bitmap:port ipsets.

This column was formerly labelled DEST PORT(S).

SPORT - {-|port-number/service-name-list|+ipset}
A comma-separated list of port numbers and/or service names from /etc/services. May also include port
ranges of the form low-port:high-port if your kernel and iptables include port range support.

Beginning with Shorewall 4.5.15, you may place '=' in this column, provided that the DPORT column is
non-empty. This causes the rule to match when either the source port or the destination port in a
packet matches one of the ports specified in DPORT.

Beginning with Shorewall 4.6.0, an ipset name can be specified in this column. This is intended to be
used with bitmap:port ipsets.

This column was formerly labelled SOURCE PORT(S).

USER – [user][:group]
May only be specified if the SOURCE zone is $FW. Specifies the effective user id and or group id of
the process sending the traffic.

This column was formerly labelled USER/GROUP.

SWITCH - [!]switch-name[={0|1}]
Added in Shorewall6 4.5.10 and allows enabling and disabling the rule without requiring shorewall6
restart.

Enables the rule if the value stored in /proc/net/nf_condition/switch-name is 1. Disables the rule if
that file contains 0 (the default). If '!' is supplied, the test is inverted such that the rule is
enabled if the file contains 0.

Within the switch-name, '@0' and '@{0}' are replaced by the name of the chain to which the rule is a
added. The switch-name (after '@...' expansion) must begin with a letter and be composed of letters,
decimal digits, underscores or hyphens. Switch names must be 30 characters or less in length.

Switches are normally off. To turn a switch on:
echo 1 >
/proc/net/nf_condition/switch-name
To turn it off again:
echo 0 >
/proc/net/nf_condition/switch-name
Switch settings are retained over shorewall6 restart.

When the switch-name is followed by =0 or =1, then the switch is initialized to off or on
respectively by the start command. Other commands do not affect the switch setting.

EXAMPLES

       Example 1:

       Use the FTP helper for TCP port 21 connections from the firewall itself.

           FORMAT 2
           #ACTION                       SOURCE            DEST               PROTO            DPORT             SPORT               USER
           CT:helper:ftp(expevents=new)  fw                -                  tcp              21

       Example 2 (Shorewall 4.5.10 or later):

       Drop traffic to/from all zones to IP address 2001:1.2.3::4

           FORMAT 2
           #ACTION                       SOURCE             DEST               PROTO            DPORT             SPORT               USER
           DROP                          all-:2001:1.2.3::4 -
           DROP                          all                2001:1.2.3::4

       or

           FORMAT 3
           #ACTION                       SOURCE             DEST               PROTO            DPORT             SPORT               USER
           DROP:P                        2001:1.2.3::4      -
           DROP:PO                       -                  2001:1.2.3::4

FILES

       /etc/shorewall6/notrack

NOTES