SHOREWALL-RULES(5)SHOREWALL-RULES(5)NAME
rules - Shorewall rules file
SYNOPSIS
/etc/shorewall/rules
DESCRIPTION
Entries in this file govern connection establishment by defining
exceptions to the policies layed 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:
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 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 and QUEUE
There is an implicit ACCEPT rule inserted at the end of this
section.
NEW
Packets in the NEW, INVALID and UNTRACKED states are processed by
rules 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 omit the ESTABLISHED and
RELATED sections and 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
ESTABLISHED and RELATED sections must be empty.
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 ORIGINAL DEST column gives the
original destination IP address of the packet and the DEST PORT(S)
column give the original destination port(s).
The columns in the file are as follows.
ACTION -
{ACCEPT[+|!]|NONAT|DROP[!]|REJECT[!]|DNAT[-]|REDIRECT[-]|CONTINUE[!]|LOG|QUEUE[!]|NFQUEUE[!]|COUNT[(queuenumber)]|COMMENT|action|macro[(target)]}[:{log-level|none}[!][:tag]]
Specifies the action to be taken if the connection request matches
the rule. 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
ACCEPT!
like ACCEPT 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.
DROP
Ignore the request.
DROP!
like DROP but exempts the rule from being suppressed by
OPTIMIZE=1 in shorewall.conf[2](5).
REJECT
disallow the request and return an icmp-unreachable or an RST
packet.
REJECT!
like REJECT but exempts the rule from being suppressed by
OPTIMIZE=1 in shorewall.conf[2](5).
DNAT
Forward the request to another system (and optionally another
port).
DNAT-
Advanced users only.
Like DNAT but only generates the DNAT iptables rule and not the
companion ACCEPT rule.
REDIRECT
Redirect the request to a server running on the firewall.
REDIRECT-
Advanced users only.
Like REDIRECT but only generates the REDIRECT iptables rule and
not the companion ACCEPT rule.
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[3](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[4](5) for additional information.
CONTINUE!
like CONTINUE but exempts the rule from being suppressed by
OPTIMIZE=1 in shorewall.conf[2](5).
LOG
Simply log the packet and continue with the next rule.
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).
NFQUEUE
Queues the packet to a user-space application using the
nfnetlink_queue mechanism. If a queuenumber is not specified,
queue zero (0) is assumed.
NFQUEUE!
like NFQUEUE 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.
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.
action
The name of an action declared in shorewall-actions[5](5) or in
/usr/share/shorewall/actions.std.
macro
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 target (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.
The ACTION 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[5](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 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
(http://www.netfilter.org/projects/ulogd/index.html).
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 -
{zone|{all|any}[+][-]}[:interface][:{address-or-range[,address-or-range]...[exclusion]|exclusion|+ipset}
Source hosts to which the rule applies. May be a zone declared in
/etc/shorewall/zones, $FW to indicate the firewall itself, all,
all+, all-, all+- or none.
When none is used either in the SOURCE or DEST column, the rule is
ignored.
all means "All Zones", including the firewall itself. all- means
"All Zones, except the firewall itself". When all[-] is used either
in the SOURCE or DEST column intra-zone traffic is not affected.
When all+[-] is "used, intra-zone traffic is affected.
Except when all[+][-] is specified, clients may be further
restricted to a list of networks and/or hosts by appending ":" and
a comma-separated list of network and/or host addresses. Hosts may
be specified by IP or MAC address; mac addresses must begin with
"~" and must use "-" as a separator.
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).
Hosts may also be specified as an IP address range using the syntax
lowaddress-highaddress. This requires that your kernel and iptables
contain iprange match support. If your kernel and iptables have
ipset match support then you may give the name of an ipset prefaced
by "+". The ipset name may be optionally followed by a number from
1 to 6 enclosed in square brackets ([]) to indicate the number of
levels of source bindings to be matched.
You may exclude certain hosts from the set already defined through
use of an exclusion (see shorewall-exclusion[6](5)).
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
DEST -
{zone|{all|any}[+][-]}[:{interface|address-or-range[,address-or-range]...[exclusion]|exclusion|+ipset}][:port[:random]]
Location of Server. May be a zone declared in
shorewall-zones[3](5), $FW to indicate the firewall itself, all.
all+ or none.
When none is used either in the SOURCE or DEST column, the rule is
ignored.
When all is used either in the SOURCE or DEST column intra-zone
traffic is not affected. When all+ is used, intra-zone traffic is
affected.
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).
The zone should be omitted in DNAT-, REDIRECT- and NONAT rules.
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.
Except when all[+]|[-] is specified, the server may be further
restricted to a particular network, host or interface by
appending ":" and the network, host or interface. See SOURCE
above.
You may exclude certain hosts from the set already defined
through use of an exclusion (see shorewall-exclusion[6](5)).
Restrictions:
1. MAC addresses are not allowed (this is a Netfilter
restriction).
2. You may not specify both an interface and an address.
Like in the SOURCE column, you may specify a range of IP
addresses using the syntax lowaddress-highaddress. When the
ACTION is DNAT or DNAT-, the connections will be assigned to
addresses in the range in a round-robin fashion.
If you kernel and iptables have ipset match support then you
may give the name of an ipset prefaced by "+". The ipset name
may be optionally followed by a number from 1 to 6 enclosed in
square brackets ([]) to indicate the number of levels of
destination bindings to be matched. Only one of the SOURCE and
DEST columns may specify an ipset name.
The port that the server is listening on may be included and
separated from the server´s IP address by ":". If omitted, the
firewall will not modifiy the destination port. A destination
port may only be included if the ACTION is DNAT or REDIRECT.
Example:
loc:192.168.1.3:3128 specifies a local server at IP address
192.168.1.3 and listening on port 3128.
The port may be specified as a service name. You may specify a port
range in the form lowport-highport to cause connections to be
assigned to ports in the range in round-robin fashion. When a port
range is specified, lowport and highport must be given as integers;
service names are not permitted. Additionally, the port range may
be optionally followed by :random which causes assignment to ports
in the list to be random.
If the ACTION is REDIRECT or REDIRECT-, this column needs only to
contain the port number on the firewall that the request should be
redirected to. That is equivalent to specifying $FW::port.
PROTO (Optional) -
{-|tcp:syn|ipp2p|ipp2p:udp|ipp2p:all|protocol-number|protocol-name|all}
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.
DEST PORT(S) (Optional) -
{-|port-name-number-or-range[,port-name-number-or-range]...}
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 numberic type and code
separated by a slash (e.g., 3/4), or a typename. See
http://www.shorewall.net/configuration_file_basics.htm#ICMP.
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
CLIENT PORT(S) list below:
1. There are 15 or less ports listed.
2. No port ranges are included or your kernel and iptables contain
extended multiport match support.
SOURCE PORT(S) (Optional) -
{-|port-name-number-or-range[,port-name-number-or-range]...}
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.
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
ORIGINAL DEST 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
DEST PORT(S) list above:
1. There are 15 or less ports listed.
2. No port ranges are included or your kernel and iptables contain
extended multiport match support.
ORIGINAL DEST (Optional) -
[-|address[,address]...[exclusion]|exclusion]
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.
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[6](5).
See http://shorewall.net/PortKnocking.html[7] for an example of
using an entry in this column with a user-defined action rule.
RATE LIMIT (Optional) - [-|[{s|d}:[[name]:]]]rate/{sec|min}[:burst]
You may 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 whitespace 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 name may be chosen
by the user and specifies a hash table to be used to count matching
connections. If not give, the name shorewallN (where N is a unique
integer) is assumed. Where more than one rule specifies the same
name, the connections counts for the rules are aggregated and the
individual rates apply to the aggregated count.
Example: s:ssh:3/min:5
USER/GROUP (Optional) -
[!][user-name-or-number][:group-name-or-number][+program-name]
This 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).
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
+upnpd
program named upnpd
Important
The ability to specify a program name was removed from
Netfilter in kernel version 2.6.14.
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 - [!]limit[:mask]
May be used to limit the number of simultaneous connections from
each individual host 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 host. 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[&timelement...]
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.
utc
Times are expressed in Greenwich Mean Time.
localtz
Times are expressed in Local Civil Time (default).
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.
EXAMPLES
Example 1:
Accept SMTP requests from the DMZ to the internet
#ACTION SOURCE DEST PROTO DEST SOURCE ORIGINAL
# PORT PORT(S) DEST
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 DEST SOURCE ORIGINAL
# PORT PORT(S) DEST
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 DEST SOURCE ORIGINAL RATE
# PORT PORT(S) DEST LIMIT
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 DEST SOURCE ORIGINAL
# PORT PORT(S) DEST
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 DEST SOURCE ORIGINAL
# PORT PORT(S) DEST
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 DEST SOURCE ORIGINAL
# PORT PORT(S) DEST
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 DEST SOURCE ORIGINAL
# PORT PORT(S) DEST
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 DEST SOURCE ORIGINAL
# PORT PORT(S) DEST
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[3](8):
#ZONE TYPE OPTIONS
fw firewall
net ipv4
dmz ipv4
loc ipv4
shorewall-interfaces[8](8):
#ZONE INTERFACE BROADCAST OPTIONS
net ppp0
loc eth1 detect
dmz eth2 detect
- ppp+ # Addresses are assigned from 192.168.3.0/24
shorewall-host[9](8):
#ZONE HOST(S) OPTIONS
loc ppp+:192.168.3.0/24
rules:
#ACTION SOURCE DEST PROTO DEST
# PORT(S)
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.
FILES
/etc/shorewall/rules
SEE ALSOshorewall(8), shorewall-accounting(5), shorewall-actions(5),
shorewall-blacklist(5), shorewall-hosts(5), shorewall-interfaces(5),
shorewall-ipsec(5), shorewall-maclist(5), shorewall-masq(5),
shorewall-nat(5), shorewall-netmap(5), shorewall-params(5),
shorewall-policy(5), shorewall-providers(5), shorewall-proxyarp(5),
shorewall-route_rules(5), shorewall-routestopped(5), shorewall.conf(5),
shorewall-tcclasses(5), shorewall-tcdevices(5), shorewall-tcrules(5),
shorewall-tos(5), shorewall-tunnels(5), shorewall-zones(5)NOTES
1. shorewall-policy
shorewall-policy.html
2. shorewall.conf
shorewall.conf.html
3. shorewall-zones
shorewall-zones.html
4. shorewall-nesting
shorewall-nesting.html
5. shorewall-actions
shorewall-actions.html
6. shorewall-exclusion
shorewall-exclusion.html
7. http://shorewall.net/PortKnocking.html
../PortKnocking.html
8. shorewall-interfaces
shorewall-interfaces.html
9. shorewall-host
shorewall-hosts.html
05/07/2010 SHOREWALL-RULES(5)
