Ubuntu Manpage: rules - Shorewall rules file

NAME

       rules - Shorewall rules file

SYNOPSIS

       /etc/shorewall[6]/rules

DESCRIPTION

Entries in this file govern connection establishment by defining exceptions to the
policies laid out in shorewall-policy[1](5). By default, subsequent requests and responses
are automatically allowed using connection tracking. For any particular (source,dest) pair
of zones, the rules are evaluated in the order in which they appear in this file and the
first terminating match is the one that determines the disposition of the request. All
rules are terminating except LOG and COUNT rules.

Warning
If you masquerade or use SNAT from a local system to the internet, you cannot use an
ACCEPT rule to allow traffic from the internet to that system. You must use a DNAT
rule instead.

The rules file is divided into sections. Each section is introduced by a "Section Header"
which is a line beginning with ?SECTION and followed by the section name.

Sections are as follows and must appear in the order listed:

ALL
This section was added in Shorewall 4.4.23. Rules in this section are applied,
regardless of the connection tracking state of the packet and are applied before rules
in the other sections.

ESTABLISHED
Packets in the ESTABLISHED state are processed by rules in this section.

The only ACTIONs allowed in this section are ACCEPT, DROP, REJECT, LOG, NFLOG, NFQUEUE
and QUEUE

There is an implicit ACCEPT rule inserted at the end of this section.

RELATED
Packets in the RELATED state are processed by rules in this section.

The only ACTIONs allowed in this section are ACCEPT, DROP, REJECT, LOG, NFLOG, NFQUEUE
and QUEUE

There is an implicit rule added at the end of this section that invokes the
RELATED_DISPOSITION (shorewall.conf[2](5)).

INVALID
Added in Shorewall 4.5.13. Packets in the INVALID state are processed by rules in this
section.

The only Actions allowed in this section are ACCEPT, DROP, REJECT, LOG, NFLOG, NFQUEUE
and QUEUE.

There is an implicit rule added at the end of this section that invokes the
INVALID_DISPOSITION (shorewall.conf[2](5)).

UNTRACKED
Added in Shorewall 4.5.13. Packets in the UNTRACKED state are processed by rules in
this section.

The only Actions allowed in this section are ACCEPT, DROP, REJECT, LOG, NFLOG, NFQUEUE
and QUEUE.

There is an implicit rule added at the end of this section that invokes the
UNTRACKED_DISPOSITION (shorewall.conf[2](5)).

NEW
Packets in the NEW state are processed by rules in this section. If the INVALID and/or
UNTRACKED sections are empty or not included, then the packets in the corresponding
state(s) are also processed in this section.

Note
If you are not familiar with Netfilter to the point where you are comfortable with the
differences between the various connection tracking states, then it is suggested that
you place all of your rules in the NEW section (That's after the line that reads
?SECTION NEW').

Warning
If you specify FASTACCEPT=Yes in shorewall.conf[2](5) then the ALL, ESTABLISHED and
RELATED sections must be empty.

An exception is made if you are running Shorewall 4.4.27 or later and you have
specified a non-default value for RELATED_DISPOSITION or RELATED_LOG_LEVEL. In that
case, you may have rules in the RELATED section of this file.

You may omit any section that you don't need. If no Section Headers appear in the file
then all rules are assumed to be in the NEW section.

When defining rules that rewrite the destination IP address and/or port number (namely
DNAT and REDIRECT rules), it is important to keep straight which columns in the file
specify the packet before rewriting and which specify how the packet will look after
rewriting.

• The DEST column specifies the final destination for the packet after rewriting and can
include the final IP address and/or port number.

• The remaining columns specify characteristics of the packet before rewriting. In
particular, the ORIGDEST column gives the original destination IP address of the
packet and the DPORT column give the original destination port(s).

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 - target[:{log-level|none}[!][:tag]]
Specifies the action to be taken if the connection request matches the rule. target
must be one of the following.

ACCEPT
Allow the connection request.

ACCEPT+
like ACCEPT but also excludes the connection from any subsequent matching DNAT[-]
or REDIRECT[-] rules. Use with IPv6 requires Shorewall 4.5.14 or later.

ACCEPT!
like ACCEPT but exempts the rule from being suppressed by OPTIMIZE=1 in
shorewall.conf[2](5).

action
The name of an action declared in shorewall-actions[3](5) or in
/usr/share/shorewall[6]/actions.std.

ADD(ipset:flags[:timeout])
Added in Shorewall 4.4.12. Causes addresses and/or port numbers to be added to the
named ipset. The flags specify the address or tuple to be added to the set and
must match the type of ipset involved. For example, for an iphash ipset, either
the SOURCE or DESTINATION address can be added using flags src or dst respectively
(see the -A command in ipset (8)).

Beginning with Shorewall 5.0.3, an optional timeout can be specified. This is the
number of seconds that the new entry in the ipset is to remain valid and overrides
any timeout specified when the ipset was created.

ADD is non-terminating. Even if a packet matches the rule, it is passed on to the
next rule.

AUDIT[(accept|drop|reject)]
Added in Shorewall 4.5.10. Audits the packet with the specified type; if the type
is omitted, then drop is assumed. Require AUDIT_TARGET support in the kernel and
iptables.

A_ACCEPT, A_ACCEPT+ and A_ACCEPT!
Added in Shorewall 4.4.20. Audited versions of ACCEPT, ACCEPT+ and ACCEPT!
respectively. Require AUDIT_TARGET support in the kernel and iptables. A_ACCEPT+
with IPv6 requires Shorewall 4.5.14 or later.

A_DROP and A_DROP!
Added in Shorewall 4.4.20. Audited versions of DROP and DROP! respectively.
Require AUDIT_TARGET support in the kernel and iptables.

A_REJECT AND A_REJECT!
Added in Shorewall 4.4.20. Audited versions of REJECT and REJECT! respectively.
Require AUDIT_TARGET support in the kernel and iptables.

?COMMENT
the rest of the line will be attached as a comment to the Netfilter rule(s)
generated by the following entries. The comment will appear delimited by "/* ...
*/" in the output of "shorewall show <chain>". To stop the comment from being
attached to further rules, simply include ?COMMENT on a line by itself.

CONMARK({mark})
Added in Shorewall 5.0.7, CONNMARK is identical to MARK with the exception that
the mark is assigned to connection to which the packet belongs is marked rather
than to the packet itself.

CONTINUE
For experts only.

Do not process any of the following rules for this (source zone,destination zone).
If the source and/or destination IP address falls into a zone defined later in
shorewall-zones[4](5) or in a parent zone of the source or destination zones, then
this connection request will be passed to the rules defined for that (those)
zone(s). See shorewall-nesting[5](5) for additional information.

CONTINUE!
like CONTINUE but exempts the rule from being suppressed by OPTIMIZE=1 in
shorewall.conf[2](5).

COUNT
Simply increment the rule's packet and byte count and pass the packet to the next
rule.

DEL(ipset:flags)
Added in Shorewall 4.4.12. Causes an entry to be deleted from the named ipset. The
flags specify the address or tuple to be deleted from the set and must match the
type of ipset involved. For example, for an iphash ipset, either the SOURCE or
DESTINATION address can be deleted using flags src or dst respectively (see the -D
command in ipset (8)).

DEL is non-terminating. Even if a packet matches the rule, it is passed on to the
next rule.

DNAT
Forward the request to another system (and optionally another port). Use with IPv6
requires Shorewall 4.5.14 or later.

DNAT-
Advanced users only.

Like DNAT but only generates the DNAT iptables rule and not the companion ACCEPT
rule. Use with IPv6 requires Shorewall 4.5.14 or later.

DROP
Ignore the request.

DROP!
like DROP but exempts the rule from being suppressed by OPTIMIZE=1 in
shorewall.conf[2](5).

HELPER
Added in Shorewall 4.5.7. This action requires that the HELPER column contains the
name of the Netfilter helper to be associated with connections matching this
connection. May only be specified in the NEW section and is useful for being able
to specify a helper when the applicable policy is ACCEPT. No destination zone
should be specified in HELPER rules.

INLINE[(action)]
Added in Shorewall 4.5.16. This action allows you to construct most of the rule
yourself using iptables syntax. The part that you specify must follow two
semicolons (';;') (preferred) or a single semicolon (';') (deprecated) and is
completely free-form. If the target of the rule (the part following 'j') is
something that Shorewall supports in the ACTION column, then you may enclose it in
parentheses (e.g., INLINE(ACCEPT)). Otherwise, you can include it after the
semicolon(s). In this case, you must declare the target as a builtin action in
shorewall-actions[3](5).

Some considerations when using INLINE:

• The p, s, d, i, o, policy, and state match (state or conntrack --ctstate)
matches will always appear in the front of the rule in that order.

• When multiple matches are specified, the compiler will keep them in the order
in which they appear (excluding the above listed ones), but they will not
necessarily be at the end of the generated rule. For example, if addresses are
specified in the SOURCE and/or DEST columns, their generated matches will
appear after those specified using ';;' or ';'.

IPTABLES({iptables-target [option ...])
IPv4 only. This action allows you to specify an iptables target with options
(e.g., 'IPTABLES(MARK --set-xmark 0x01/0xff)'. If the iptables-target is not one
recognized by Shorewall, the following error message will be issued:

ERROR: Unknown target (iptables-target)

This error message may be eliminated by adding the iptables-target as a builtin
action in shorewall-actions[3](5).

Important
If you specify REJECT as the iptables-target, the target of the rule will be
the iptables REJECT target and not Shorewall's builtin 'reject' chain which is
used when REJECT (see below) is specified as the target in the ACTION column.

IP6TABLES({ip6tables-target [option ...])
IPv6 only. This action allows you to specify an ip6tables target with options
(e.g., 'IPTABLES(MARK --set-xmark 0x01/0xff)'. If the ip6tables-target is not one
recognized by Shorewall, the following error message will be issued:

ERROR: Unknown target (ip6tables-target)

This error message may be eliminated by adding the ip6tables-target as a builtin
action in shorewall-actions[6](5).

Important
If you specify REJECT as the ip6tables-target, the target of the rule will be
the i6ptables REJECT target and not Shorewall's builtin 'reject' chain which
is used when REJECT (see below) is specified as the target in the ACTION
column.

LOG:level
Simply log the packet and continue with the next rule.

macro[(macrotarget)]
The name of a macro defined in a file named macro.macro. If the macro accepts an
action parameter (Look at the macro source to see if it has PARAM in the TARGET
column) then the macro name is followed by the parenthesized macrotarget (ACCEPT,
DROP, REJECT, ...) to be substituted for the parameter.

Example: FTP(ACCEPT).

The older syntax where the macro name and the target are separated by a slash
(e.g. FTP/ACCEPT) is still allowed but is deprecated.

MARK({mark})
where mark is a packet mark value.

Added in Shorewall 5.0.7, MARK requires "Mark in filter table" support in your
kernel and iptables.

Normally will set the mark value of the current packet. If preceded by a vertical
bar ("|"), the mark value will be logically ORed with the current mark value to
produce a new mark value. If preceded by an ampersand ("&"), will be logically
ANDed with the current mark value to produce a new mark value.

Both "|" and "&" require Extended MARK Target support in your kernel and iptables.

The mark value may be optionally followed by "/" and a mask value (used to
determine those bits of the connection mark to actually be set). When a mask is
specified, the result of logically ANDing the mark value with the mask must be the
same as the mark value.

NFLOG[(nflog-parameters)]
Added in Shorewall 4.5.9.3. Queues matching packets to a back end logging daemon
via a netlink socket then continues to the next rule. See
http://www.shorewall.net/shorewall_logging.html[7].

The nflog-parameters are a comma-separated list of up to 3 numbers:

• The first number specifies the netlink group (0-65535). If omitted (e.g.,
NFLOG(,0,10)) then a value of 0 is assumed.

• The second number specifies the maximum number of bytes to copy. If omitted, 0
(no limit) is assumed.

• The third number specifies the number of log messages that should be buffered
in the kernel before they are sent to user space. The default is 1.

NFLOG is similar to LOG:NFLOG[(nflog-parameters)], except that the log level is
not changed when this ACTION is used in an action or macro body and the invocation
of that action or macro specifies a log level.

NFQUEUE[([queuenumber1[:queuenumber2[c]][,bypass]]|bypass)]
Queues the packet to a user-space application using the nfnetlink_queue mechanism.
If a queuenumber1 is not specified, queue zero (0) is assumed. Beginning with
Shorewall 4.6.10, the keyword bypass can be given. By default, if no userspace
program is listening on an NFQUEUE, then all packets that are to be queued are
dropped. When this option is used, the NFQUEUE rule is silently bypassed instead.
The packet will move on to the next rule. Also beginning in Shorewall 4.6.10, a
second queue number (queuenumber2) may be specified. This specifies a range of
queues to use. Packets are then balanced across the given queues. This is useful
for multicore systems: start multiple instances of the userspace program on queues
x, x+1, .. x+n and use "x:x+n". Packets belonging to the same connection are put
into the same nfqueue.

Beginning with Shorewall 5.1.0, queuenumber2 may be followed by the letter 'c' to
indicate that the CPU ID will be used as an index to map packets to the queues.
The idea is that you can improve performance if there's a queue per CPU. Requires
the NFQUEUE CPU Fanout capability in your kernel and iptables.

NFQUEUE![([queuenumber1[:queuenumber2[c]][,bypass]]|bypass)]
like NFQUEUE but exempts the rule from being suppressed by OPTIMIZE=1 in
shorewall.conf[2](5).

NONAT
Excludes the connection from any subsequent DNAT[-] or REDIRECT[-] rules but
doesn't generate a rule to accept the traffic. Use with IPv6 requires Shorewall
4.5.14 or later.

QUEUE
Queue the packet to a user-space application such as ftwall
(http://p2pwall.sf.net). The application may reinsert the packet for further
processing.

QUEUE!
like QUEUE but exempts the rule from being suppressed by OPTIMIZE=1 in
shorewall.conf[2](5).

REJECT[(option)]
disallow the request and return an icmp-unreachable or an RST packet. If no option
is passed, Shorewall selects the appropriate option based on the protocol of the
packet.

Beginning with Shorewall 5.0.8, the type of reject may be specified in the option
paramater. Valid IPv4 option values are:
icmp-net-unreachable
icmp-host-unreachable
icmp-port-unreachable
icmp-proto-unreachable
icmp-net-prohibited
icmp-host-prohibited
icmp-admin-prohibited
icmp-tcp-reset (the PROTO column
must specify TCP). Beginning with Shorewall 5.1.3, this
option may also be specified as
tcp-reset.
Valid IPv6 option values are:
icmp6-no-route
no-route
icmp6-adm-prohibited
adm-prohibited
icmp6-addr-unreachable
addr-unreach
icmp6-port-unreachable
tcp-reset (the PROTO column must
specify TCP)

REJECT!
like REJECT but exempts the rule from being suppressed by OPTIMIZE=1 in
shorewall.conf[2](5).

REDIRECT
Redirect the request to a server running on the firewall. Use with IPv6 requires
Shorewall 4.5.14 or later.

REDIRECT-
Advanced users only.

Like REDIRECT but only generates the REDIRECT iptables rule and not the companion
ACCEPT rule. Use with IPv6 requires Shorewall 4.5.14 or later.

TARPIT [(tarpit | honeypot | reset)]
Added in Shorewall 4.6.6.

TARPIT captures and holds incoming TCP connections using no local per-connection
resources.

TARPIT only works with the PROTO column set to tcp (6), and is totally application
agnostic. This module will answer a TCP request and play along like a listening
server, but aside from sending an ACK or RST, no data is sent. Incoming packets
are ignored and dropped. The attacker will terminate the session eventually. This
module allows the initial packets of an attack to be captured by other software
for inspection. In most cases this is sufficient to determine the nature of the
attack.

This offers similar functionality to LaBrea <http://www.hackbusters.net/LaBrea/>
but does not require dedicated hardware or IPs. Any TCP port that you would
normally DROP or REJECT can instead become a tarpit.

The target accepts a single optional parameter:

tarpit
This mode is the default and completes a connection with the attacker but
limits the window size to 0, thus keeping the attacker waiting long periods of
time. While he is maintaining state of the connection and trying to continue
every 60-240 seconds, we keep none, so it is very lightweight. Attempts to
close the connection are ignored, forcing the remote side to time out the
connection in 12-24 minutes.

honeypot
This mode completes a connection with the attacker, but signals a normal
window size, so that the remote side will attempt to send data, often with
some very nasty exploit attempts. We can capture these packets for decoding
and further analysis. The module does not send any data, so if the remote
expects an application level response, the game is up.

reset
This mode is handy because we can send an inline RST (reset). It has no other
function.

ULOG[(ulog-parameters)]
IPv4 only. Added in Shorewall 4.5.10. Queues matching packets to a back end
logging daemon via a netlink socket then continues to the next rule. See
shorewall-logging(5)[8].

Similar to LOG:ULOG[(ulog-parameters)], except that the log level is not changed
when this ACTION is used in an action or macro body and the invocation of that
action or macro specifies a log level.

The target may optionally be followed by ":" and a syslog log level (e.g, REJECT:info
or Web(ACCEPT):debug). This causes the packet to be logged at the specified level.
Note that if the ACTION involves destination network address translation (DNAT,
REDIRECT, etc.) then the packet is logged before the destination address is rewritten.

If the ACTION names an action declared in shorewall-actions[3](5) or in
/usr/share/shorewall/actions.std then:

• If the log level is followed by "!' then all rules in the action are logged at the
log level.

• If the log level is not followed by "!" then only those rules in the action that
do not specify logging are logged at the specified level.

• The special log level none! suppresses logging by the action.

You may also specify ULOG (IPv4 only) or NFLOG (must be in upper case) as a log
level.This will log to the ULOG or NFLOG target for routing to a separate log through
use of ulogd (shorewall-logging(5)[8]).

Actions specifying logging may be followed by a log tag (a string of alphanumeric
characters) which is appended to the string generated by the LOGPREFIX (in
shorewall.conf[2](5)).

Example: ACCEPT:info:ftp would include 'ftp ' at the end of the log prefix generated
by the LOGPREFIX setting.

SOURCE - source-spec[,...]
Source hosts to which the rule applies.

source-spec is one of the following:

zone[,...[+]]
The name of a zone defined in shorewall-zones[4](5). When only the zone name is
specified, the packet source may be any host in that zone.

zone may also be one of the following:

all[+][-]
all, without the "-" means "All Zones, including the firewall zone". If the
"-" is included, the firewall zone is omitted. Normally all omits intra-zone
traffic, but intra-zone traffic can be included specifying "+".

any[+][-]
any is equivalent to all when there are no nested zones. When there are nested
zones, any only refers to top-level zones (those with no parent zones). Note
that any excludes all vserver zones, since those zones are nested within the
firewall zone.

none
When none is used either in the SOURCE or DEST column, the rule is ignored.

Similar to with all and any, intra-zone traffic is normally excluded when multiple
zones are listed. Intra-zone traffic may be included by following the list with a
plus sign ("+").

all and any may be followed by an exclamation point ("!") and a comma-separated
list of zone names to be omitted.

zone:interface
When this form is used, interface must be the name of an interface associated with
the named zone in either shorewall-interfaces[9](5) or shorewall-hosts[10](5).
Only packets from hosts in the zone that arrive through the named interface will
match the rule.

zone:address[,...]
where address can be:

• A host or network IP address. A network address may be followed by exclusion
(see shorewall-exclusion[11](5)).

• An address range, specified using the syntax lowaddress-highaddress.

• +ipset where ipset is the name of an ipset and must be preceded by a plus sign
("+").

• A MAC address in Shorewall format (preceded by a tilde ("~") and with the hex
byte values separated by dashes (e.g., "~00-0a-f6-04-9c-7d").

• ^country-code where country-code is a two-character ISO-3661 country code
preceded by a caret ("^").

• ^country-code-list where country-code-list is a comma-separated list of up to
15 ISO-3661 country codes enclosed in square brackets ("[...]").

• The primary IP address of a firewall interface can be specified by an
ampersand ('&') followed by the logical name of the interface as found in the
INTERFACE column of shorewall-interfaces[9] (5).

zone:interface:address[,...]
This form combines the preceding two and requires that both the incoming interface
and source address match.

zone:exclusion
This form matches if the host IP address does not match any of the entries in the
exclusion (see shorewall-exclusion[11](5)).

zone:interface:exclusion
This form matches packets from the named zone entering through the specified
interface where the source address does not match any entry in the exclusion.

Beginning with Shorewall 5.1.0, multiple source-specs may be listed, provided that
extended forms of the source-spec are used: zone:(interface)

zone:(address[,...])

zone:(interface:address[,...])

zone:(exclusion)

zone:(interface:exclusion) Examples:

dmz:192.168.2.2
Host 192.168.2.2 in the DMZ

net:155.186.235.0/24
Subnet 155.186.235.0/24 on the Internet

loc:192.168.1.1,192.168.1.2
Hosts 192.168.1.1 and 192.168.1.2 in the local zone.

loc:~00-A0-C9-15-39-78
Host in the local zone with MAC address 00:A0:C9:15:39:78.

net:192.0.2.11-192.0.2.17
Hosts 192.0.2.11-192.0.2.17 in the net zone.

net:!192.0.2.11-192.0.2.17
All hosts in the net zone except for 192.0.2.11-192.0.2.17.

net:155.186.235.0/24!155.186.235.16/28
Subnet 155.186.235.0/24 on the Internet except for 155.186.235.16/28

$FW:&eth0
The primary IP address of eth0 in the firewall zone.

loc,dmz
Both the loc and dmz zones.

all!dmz
All but the dmz zone.

net:^CN
China.

loc:(eth1:1.2.3.4,2.3.4.5),dmz:(eth2:5.6.7.8,9.10.11.12),net
Hosts 1.2.3.4 and 2.3.4.5 in the loc zone when the packet arrives through eth1
plus hosts 5.6.7.8 and 9.10.11.12 in the dmz zone when the packet arrives through
eth2 plus all of the net zone.

dmz:[2002:ce7c:2b4:1::2]
Host 2002:ce7c:92b4:1::2 in the DMZ

net:2001:4d48:ad51:24::/64
Subnet 2001:4d48:ad51:24::/64 on the Internet

loc:[2002:cec792b4:1::2],[2002:cec792b4:1::44]
Hosts 2002:cec792b4:1::2 and 2002:cec792b4:1::44 in the local zone.

loc:~00-A0-C9-15-39-78
Host in the local zone with MAC address 00:A0:C9:15:39:78.

net:[2001:4d48:ad51:24::]/64![2001:4d48:ad51:24:6::]/80
Subnet 2001:4d48:ad51:24::/64 on the Internet except for 2001:4d48:ad51:24:6::/80.

DEST - dest-spec[,...]
Destination hosts to which the rule applies.

dest-spec is one of the following:

zone[,...[+]]
The name of a zone defined in shorewall-zones[4](5). When only the zone name is
specified, the packet destination may be any host in that zone.

zone may also be one of the following:

none
When none is used either in the SOURCE or DEST column, the rule is ignored.

Similar to with all and any, intra-zone traffic is normally excluded when multiple
zones are listed. Intra-zone traffic may be included by following the list with a
plus sign ("+").

all and any may be followed by an exclamation point ("!") and a comma-separated
list of zone names to be omitted.

zone:interface
When this form is used, interface must be the name of an interface associated with
the named zone in either shorewall-interfaces[9](5) or shorewall-hosts[12](5).
Only packets to hosts in the zone that are sent through the named interface will
match the rule.

zone:address[,...]
where address can be:

• A host or network IP address. A network address may be followed by exclusion
(see shorewall-exclusion[11](5)).

• An address range, specified using the syntax lowaddress-highaddress.

• +ipset where ipset is the name of an ipset and must be preceded by a plus sign
("+").

• ^country-code where country-code is a two-character ISO-3661 country code
preceded by a caret ("^").

• ^country-code-list where country-code-list is a comma-separated list of up to
15 ISO-3661 country codes enclosed in square brackets ("[...]").

zone:interface:address[,...]
This form combines the preceding two and requires that both the outgoing interface
and destinationaddress match.

zone:exclusion
This form matches if the host IP address does not match any of the entries in the
exclusion (see shorewall-exclusion[11](5)).

zone:interface:exclusion
This form matches packets to the named zone leaving through the specified
interface where the destination address does not match any entry in the exclusion.

[zone]:[server-IP][:port-or-port-range[:random]]
This form applies when the ACTION is DNAT[-] or REDIRECT[-]. The zone may be
omitted in REDIRECT rules ($FW is assumed) and must be omitted in DNAT-, REDIRECT-
and NONAT rules.

server-IP is not allowed in REDIRECT rules and may be omitted in DNAT[-] rules
provided that port-or-port-range is included.

• The IP address of the server to which the packet is to be sent.

• A range of IP address with the low and high address separated by a dash
(:"-"). Connections are distributed among the IP addresses in the range.

If server-IP is omitted in a DNAT[-] rule, only the destination port number is
modified by the rule.

port-or-port-range may be:

• An integer port number in the range 1 - 65535.

• The name of a service from /etc/services.

• A port range with the low and high integer port numbers separated by a dash
("-"). Connections are distributed among the ports in the range.

If random is specified, port mapping will be randomized.

If the DEST zone is a bport zone, then either:

1. the SOURCE must be all[+][-], or

2. the SOURCE zone must be another bport zone associated with the same bridge, or

3. the SOURCE zone must be an ipv4 zone that is associated with only the same bridge.

Beginning with Shorewall 5.1.0, multiple dest-specs may be listed, provided that
extended forms of the source-spec are used: zone:(interface)

zone:(address[,...])

zone:(interface:address[,...])

zone:(exclusion)

zone:(interface:exclusion) Multiple dest-specs are not permitted in DNAT[-] and
REDIRECT[-] rules.

Examples:

dmz:192.168.2.2
Host 192.168.2.2 in the DMZ

net:155.186.235.0/24
Subnet 155.186.235.0/24 on the Internet

loc:192.168.1.1,192.168.1.2
Hosts 192.168.1.1 and 192.168.1.2 in the local zone.

net:192.0.2.11-192.0.2.17
Hosts 192.0.2.11-192.0.2.17 in the net zone.

net:!192.0.2.11-192.0.2.17
All hosts in the net zone except for 192.0.2.11-192.0.2.17.

net:155.186.235.0/24!155.186.235.16/28
Subnet 155.186.235.0/24 on the Internet except for 155.186.235.16/28

$FW:&eth0
The primary IP address of eth0 in the firewall zone.

loc,dmz
Both the loc and dmz zones.

all!dmz
All but the dmz zone.

net:^CN
China.

dmz:192.168.10.4:25
Port 25 on server 192.168.10.4 in the dmz zone (DNAT rule).

PROTO- {-|tcp:[!]syn|ipp2p|ipp2p:udp|ipp2p:all|protocol-number|protocol-name|all}
Optional Protocol - ipp2p* requires ipp2p match support in your kernel and iptables.
tcp:syn implies tcp plus the SYN flag must be set and the RST, ACK and FIN flags must
be reset. Beginning with Shorewall 5.1.3, you may also specify tcp:!syn, which matches
if SYN is not set or if RST, ACK or FIN is set.

Beginning with Shorewall 4.4.19, this column can contain a comma-separated list of
protocol-numbers and/or protocol names.

DPORT - {-|port-name-number-or-range[,port-name-number-or-range]...|+ipset}
Optional destination Ports. A comma-separated list of Port names (from services(5)),
port numbers or port ranges; if the protocol is icmp, this column is interpreted as
the destination icmp-type(s). ICMP types may be specified as a numeric type, a numeric
type and code separated by a slash (e.g., 3/4), or a typename. See
http://www.shorewall.net/configuration_file_basics.htm#ICMP[13]. Note that prior to
Shorewall 4.4.19, only a single ICMP type may be listed.

If the protocol is ipp2p, this column is interpreted as an ipp2p option without the
leading "--" (example bit for bit-torrent). If no port is given, ipp2p is assumed.

A port range is expressed as lowport:highport.

This column is ignored if PROTO = all but must be entered if any of the following
columns are supplied. In that case, it is suggested that this field contain a dash
(-).

If your kernel contains multi-port match support, then only a single Netfilter rule
will be generated if in this list and the SPORT list below:

1. There are 15 or less ports listed.

2. No port ranges are included or your kernel and iptables contain extended multi-port
match 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-name-number-or-range[,port-name-number-or-range]...|+ipset}
Optional port(s) used by the client. If omitted, any source port is acceptable.
Specified as a comma- separated list of port names, port numbers or port ranges.

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 DEST
PORTS(S). Use of '=' requires multi-port match in your iptables and kernel.

Warning
Unless you really understand IP, you should leave this column empty or place a
dash (-) in the column. Most people who try to use this column get it wrong.
If you don't want to restrict client ports but need to specify an ORIGDEST in the next
column, then place "-" in this column.

If your kernel contains multi-port match support, then only a single Netfilter rule
will be generated if in this list and the DPORT list above:

1. There are 15 or less ports listed.

2. No port ranges are included or your kernel and iptables contain extended multi-port
match 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 SOURCE PORT(S).

ORIGDEST - [-|address[,address]...[exclusion]|exclusion]
Optional. If ACTION is DNAT[-] or REDIRECT[-] then if this column is included and is
different from the IP address given in the DEST column, then connections destined for
that address will be forwarded to the IP and port specified in the DEST column.

A comma-separated list of addresses may also be used. This is most useful with the
REDIRECT target where you want to redirect traffic destined for particular set of
hosts. Finally, if the list of addresses begins with "!" (exclusion) then the rule
will be followed only if the original destination address in the connection request
does not match any of the addresses listed.

Beginning with Shorewall 4.4.17, the primary IP address of a firewall interface can be
specified by an ampersand ('&') followed by the logical name of the interface as found
in the INTERFACE column of shorewall-interfaces[9] (5).

For other actions, this column may be included and may contain one or more addresses
(host or network) separated by commas. Address ranges are not allowed. When this
column is supplied, rules are generated that require that the original destination
address matches one of the listed addresses. This feature is most useful when you want
to generate a filter rule that corresponds to a DNAT- or REDIRECT- rule. In this
usage, the list of addresses should not begin with "!".

It is also possible to specify a set of addresses then exclude part of those
addresses. For example, 192.168.1.0/24!192.168.1.16/28 specifies the addresses
192.168.1.0-182.168.1.15 and 192.168.1.32-192.168.1.255. See
shorewall-exclusion[11](5).

See http://www.shorewall.net/PortKnocking.html[14] for an example of using an entry in
this column with a user-defined action rule.

This column was formerly labelled ORIGINAL DEST.

RATE - limit
where limit is one of:
[-|[{s|d}:[[name]:]]]rate/{sec|min|hour|day}[:burst]
[name1]:rate1/{sec|min|hour|day}[:burst1],[name2]:rate2/{sec|min|hour|day}[:burst2]
You may optionally rate-limit the rule by placing a value in this column:

rate* is the number of connections per interval (sec or min) and burst* is the largest
burst permitted. If no burst is given, a value of 5 is assumed. There may be no no
white-space embedded in the specification.

Example: 10/sec:20

When s: or d: is specified, the rate applies per source IP address or per destination
IP address respectively. The names may be chosen by the user and specify a hash table
to be used to count matching connections. If not given, the name shorewallN (where N
is a unique integer) is assumed. Where more than one rule or POLICY specifies the same
name, the connections counts for the rules are aggregated and the individual rates
apply to the aggregated count.

Beginning with Shorewall 4.6.5, two limits may be specified, separated by a comma. In
this case, the first limit (name1, rate1, burst1) specifies the per-source IP limit
and the second limit specifies the per-destination IP limit.

Example: client:10/sec:20,:60/sec:100

In this example, the 'client' hash table will be used to enforce the per-source limit
and the compiler will pick a unique name for the hash table that tracks the
per-destination limit.

This column was formerly labelled RATE LIMIT.

USER - [!][user-name-or-number][:group-name-or-number][,...]
This optional column may only be non-empty if the SOURCE is the firewall itself.

When this column is non-empty, the rule applies only if the program generating the
output is running under the effective user and/or group specified (or is NOT running
under that id if "!" is given).

Beginning with Shorewall 4.5.8, multiple user or group names/ids separated by commas
may be specified.

Examples:

joe
program must be run by joe

:kids
program must be run by a member of the 'kids' group

!:kids
program must not be run by a member of the 'kids' group

2001-2099
UIDs 2001 through 2099 (Shorewall 4.5.6 and later)

This column was formerly labelled USER/GROUP.

MARK - [!]value[/mask][:C]
Defines a test on the existing packet or connection mark. The rule will match only if
the test returns true.

If you don't want to define a test but need to specify anything in the following
columns, place a "-" in this field.

!
Inverts the test (not equal)

value
Value of the packet or connection mark.

mask
A mask to be applied to the mark before testing.

:C
Designates a connection mark. If omitted, the packet mark's value is tested.

CONNLIMIT - [d:][!]limit[:mask]
May be used to limit the number of simultaneous connections to/from each individual
host or network to limit connections. Requires connlimit match in your kernel and
iptables. While the limit is only checked on rules specifying CONNLIMIT, the number of
current connections is calculated over all current connections from the SOURCE or
DESTINATION host. By default, limiting is done by SOURCE host or net, but if the
specification begins with d:, then limiting will be donw by destination host or net.

By default, the limit is applied to each host but can be made to apply to networks of
hosts by specifying a mask. The mask specifies the width of a VLSM mask to be applied
to the source address; the number of current connections is then taken over all hosts
in the subnet source-address/mask. When ! is specified, the rule matches when the
number of connection exceeds the limit.

TIME - timeelement[&timeelement...]
May be used to limit the rule to a particular time period each day, to particular days
of the week or month, or to a range defined by dates and times. Requires time match
support in your kernel and iptables.

timeelement may be:

timestart=hh:mm[:ss]
Defines the starting time of day.

timestop=hh:mm[:ss]
Defines the ending time of day.

contiguous
Added in Shoreawll 5.0.12. When timestop is smaller than timestart value, match
this as a single time period instead of distinct intervals.

utc
Times are expressed in Greenwich Mean Time.

localtz
Deprecated by the Netfilter team in favor of kerneltz. Times are expressed in
Local Civil Time (default).

kerneltz
Added in Shorewall 4.5.2. Times are expressed in Local Kernel Time (requires
iptables 1.4.12 or later).

weekdays=ddd[,ddd]...
where ddd is one of Mon, Tue, Wed, Thu, Fri, Sat or Sun

monthdays=dd[,dd],...
where dd is an ordinal day of the month

datestart=yyyy[-mm[-dd[Thh[:mm[:ss]]]]]
Defines the starting date and time.

datestop=yyyy[-mm[-dd[Thh[:mm[:ss]]]]]
Defines the ending date and time.

HEADERS - [!][any:|exactly:]header-list (Optional - Added in Shorewall 4.4.15)
This column is only used in IPv6. In IPv4, supply "-" in this column if you with to
place a value in one of the following columns.

The header-list consists of a comma-separated list of headers from the following list.

auth, ah, or 51
Authentication Headers extension header.

esp, or 50
Encrypted Security Payload extension header.

hop, hop-by-hop or 0
Hop-by-hop options extension header.

route, ipv6-route or 43
IPv6 Route extension header.

frag, ipv6-frag or 44
IPv6 fragmentation extension header.

none, ipv6-nonxt or 59
No next header

proto, protocol or 255
Any protocol header.

If any: is specified, the rule will match if any of the listed headers are present. If
exactly: is specified, the will match packets that exactly include all specified
headers. If neither is given, any: is assumed.

If ! is entered, the rule will match those packets which would not be matched when !
is omitted.

SWITCH - [!]switch-name[={0|1}]
Added in Shorewall 4.4.24 and allows enabling and disabling the rule without requiring
shorewall restart.

The rule is enabled if the value stored in /proc/net/nf_condition/switch-name is 1.
The rule is disabled 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 shorewall restart.

Beginning with Shorewall 4.5.10, 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.

HELPER - [helper]
Added in Shorewall 4.5.7.

In the NEW section, causes the named conntrack helper to be associated with this
connection; the contents of this column are ignored unless ACTION is ACCEPT*, DNAT* or
REDIRECT*.

In the RELATED section, will only match if the related connection has the named helper
associated with it.

The helper may be one of:
amanda
ftp
irc
netbios-ns
pptp
Q.931
RAS
sane
sip
snmp
tftp
If the HELPERS option is specified in shorewall.conf[2](5), then any module specified
in this column must be listed in the HELPERS setting.

EXAMPLES

       Example 1:
           Accept SMTP requests from the DMZ to the internet

                        #ACTION SOURCE  DEST      PROTO      DPORT   SPORT   ORIGDEST
                        ACCEPT  dmz     net       tcp        smtp

       Example 2:
           Forward all ssh and http connection requests from the internet to local system
           192.168.1.3

                       #ACTION SOURCE  DEST            PROTO   DPORT   SPORT   ORIGDEST
                       DNAT    net     loc:192.168.1.3 tcp     ssh,http

       Example 3:
           Forward all http connection requests from the internet to local system 192.168.1.3
           with a limit of 3 per second and a maximum burst of 10

                       #ACTION SOURCE DEST             PROTO  DPORT SPORT   ORIGDEST RATE
                       DNAT    net    loc:192.168.1.3  tcp    http  -       -        3/sec:10

       Example 4:
           Redirect all locally-originating www connection requests to port 3128 on the firewall
           (Squid running on the firewall system) except when the destination address is
           192.168.2.2

                       #ACTION  SOURCE DEST      PROTO DPORT   SPORT   ORIGDEST
                       REDIRECT loc    3128      tcp   www      -      !192.168.2.2

       Example 5:
           All http requests from the internet to address 130.252.100.69 are to be forwarded to
           192.168.1.3

                       #ACTION  SOURCE DEST            PROTO   DPORT   SPORT   ORIGDEST
                       DNAT      net   loc:192.168.1.3 tcp     80      -       130.252.100.69

       Example 6:
           You want to accept SSH connections to your firewall only from internet IP addresses
           130.252.100.69 and 130.252.100.70

                       #ACTION  SOURCE DEST            PROTO   DPORT   SPORT   ORIGDEST
                       ACCEPT   net:130.252.100.69,130.252.100.70 \
                                       $FW             tcp     22

       Example 7:
           You wish to accept connections from the internet to your firewall on port 2222 and you
           want to forward them to local system 192.168.1.3, port 22

                       #ACTION  SOURCE DEST                PROTO   DPORT   SPORT   ORIGDEST
                       DNAT     net    loc:192.168.1.3:22  tcp     2222

       Example 8:
           You want to redirect connection requests to port 80 randomly to the port range 81-90.

                       #ACTION  SOURCE DEST                PROTO DPORT   SPORT   ORIGDEST
                       REDIRECT net    $FW::81-90:random   tcp   www

       Example 9:
           Shorewall does not impose as much structure on the Netfilter rules in the 'nat' table
           as it does on those in the filter table. As a consequence, when using Shorewall
           versions before 4.1.4, care must be exercised when using DNAT and REDIRECT rules with
           zones defined with wildcard interfaces (those ending with '+'. Here is an example:

           shorewall-zones[4](5):

                       #ZONE       TYPE    OPTIONS
                       fw          firewall
                       net         ipv4
                       dmz         ipv4
                       loc         ipv4

           shorewall-interfaces[9](5):

                       #ZONE       INTERFACE       BROADCAST      OPTIONS
                       net         ppp0
                       loc         eth1            detect
                       dmz         eth2            detect
                       -           ppp+                           # Addresses are assigned from 192.168.3.0/24

           shorewall-host[12](5):

                       #ZONE       HOST(S)              OPTIONS
                       loc         ppp+:192.168.3.0/24

           rules:

                       #ACTION     SOURCE          DEST       PROTO       DPORT
                       REDIRECT    loc             3128       tcp         80

           Note that it would have been tempting to simply define the loc zone entirely in
           shorewall-interfaces(8):

                       #******************* INCORRECT *****************
                       #ZONE       INTERFACE       BROADCAST      OPTIONS
                       net         ppp0
                       loc         eth1            detect
                       loc         ppp+
                       dmz         eth2

           This would have made it impossible to run a internet-accessible web server in the DMZ
           because all traffic entering ppp+ interfaces would have been redirected to port 3128
           on the firewall and there would have been no net->fw ACCEPT rule for that traffic.

       Example 10:
           Add the tuple (source IP, dest port, dest IP) of an incoming SSH connection to the
           ipset S:

                       #ACTION                       SOURCE           DEST           PROTO       DPORT
                       ADD(+S:dst,src,dst)           net              fw             tcp         22

       Example 11:
           You wish to limit SSH connections from remote systems to 1/min with a burst of three
           (to allow for limited retry):

                       #ACTION     SOURCE          DEST       PROTO       DPORT        SPORT     ORIGDEST         RATE
                       SSH(ACCEPT) net             all        -           -            -         -                s:1/min:3

       Example 12:
           Forward port 80 to dmz host $BACKUP if switch 'primary_down' is on.

                       #ACTION     SOURCE          DEST        PROTO       DPORT        SPORT     ORIGDEST   RATE      USER      MARK    CONNLIMIT     TIME     HEADERS    SWITCH
                       DNAT        net             dmz:$BACKUP tcp         80           -         -          -         -         -       -             -        -          primary_down

       Example 13:
           Drop all email from the Anonymous Proxy and Satellite Provider address ranges:

                       #ACTION                       SOURCE           DEST           PROTO       DPORT
                       DROP                          net:^A1,A2       fw             tcp         25

       Example 14:
           You want to generate your own rule involving iptables targets and matches not
           supported by Shorewall.

                       #ACTION                       SOURCE           DEST           PROTO       DPORT
                       INLINE                        $FW              net ; -p 6 -m mickey-mouse --name test -m set --match-set set1 src -m mickey-mouse --name test2 -j SECCTX --name test3

           The above will generate the following iptables-restore input:

                       -A fw2net -p 6 -m mickey-mouse --name test -m set --match-set set1 src -m mickey-mouse --name test2 -j SECCTX --name test3

           Note that SECCTX must be defined as a builtin action in shorewall-actions[3](5):

                       #ACTION            OPTIONS
                       SECCTX             builtin

       Example 15:
           You want to accept SSH connections to your firewall only from internet IP addresses
           2002:ce7c::92b4:1::2 and 2002:ce7c::92b4:1::22

                       #ACTION  SOURCE DEST            PROTO   DPORT   SPORT   ORIGDEST
                       ACCEPT   net:<2002:ce7c::92b4:1::2,2002:ce7c::92b4:1::22> \
                                       $FW              tcp     22

FILES

       /etc/shorewall/rules

       /etc/shorewall6/rules

NOTES