shorewall-rules 5 rules Shorewall rules file /etc/shorewall/rules Description Entries in this file govern connection establishment by defining exceptions to the policies layed out in shorewall-policy(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 QUEUE rules. 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 and INVALID states are processed by rules in this section. 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'). If you specify FASTACCEPT=Yes in shorewall.conf(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[-]|SAME[-]|REDIRECT[-]|CONTINUE[]|LOG|QUEUE[]|NFQUEUE[(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(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(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(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. SAME Similar to DNAT except that the port may not be remapped and when multiple server addresses are listed, all requests from a given remote system go to the same server. Support for SAME is scheduled for removal from the Linux kernel in 2008. SAME- Advanced users only. Like SAME but only generates the nat 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(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) for additional information. CONTINUE! like CONTINUE but exempts the rule from being suppressed by OPTIMIZE=1 in shorewall.conf(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(5). NFQUEUE Only supported by Shorewall-perl >= 4.0.3. 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(5). 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) 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 DNAT:debug). This causes the packet to be logged at the specified level. Note that if the ACTION involves destination network address translation (DNAT, REDIRECT, SAME, etc.) then the packet is logged before the destination address is rewritten. If the ACTION names an action declared in shorewall-actions(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(5)). Example: ACCEPT:info:ftp would include 'ftp ' at the end of the log prefix generated by the LOGPREFIX setting.
SOURCE - {zone|all[+][-]}[: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. 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(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
Alternatively, clients may be specified by interface by appending ":" to the zone name followed by the interface name. For example, loc:eth1 specifies a client that communicates with the firewall system through eth1. This may be optionally followed by another colon (":") and an IP/MAC/subnet address as described above (e.g., loc:eth1:192.168.1.5). It is important to note that when using Shorewall-shell and specifying an address list that will be split (i.e., a comma separated list), there is a subtle behavior which has the potential to cause confusion. Consider the two examples below:
Examples: loc:eth1:192.168.1.3,192.168.1.5 Hosts 192.168.1.3 and 192.168.1.5 in the Local zone, with 192.168.1.3 coming from eth1 and 192.168.1.5 originating from any interface in the zone. loc:eth1:192.168.1.3,eth1:192.168.1.5 Hosts 192.168.1.3 and 192.168.1.5 in the Local zone, with both originating from eth1.
That is, the interface name must be explicitly stated for each member of the comma separated list. Again, this distinction in behavior only occurs when using Shorewall-shell.
DEST - {zone|all[+][-]}[:{interface|address-or-range[,address-or-range]...[exclusion]|exclusion|+ipset}][port[:random]] Location of Server. May be a zone declared in shorewall-zones(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. Beginning with Shorewall 4.1.4, the zone should be omitted in DNAT-, REDIRECT- and NONAT rules. If the DEST zone is a bport zone, then either: the SOURCE must be , or the SOURCE zone must be another bport zone associated with the same bridge, or 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(5)). Restrictions: 1. MAC addresses are not allowed (this is a Netfilter restriction). 2.Prior to Shorewall 4.1.4, only IP addresses are allowed in DNAT rules; no DNS names are permitted. In no case may a network be specified as the server. 3. 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. If you are using Shorewall-shell or Shorewall-perl before version 4.0.5, then the port number MUST be specified as an integer and not as a name from services(5). Shorewall-perl 4.0.5 and later permit the port to be specified as a service name. Additionally, Shorewall-perl 4.0.5 and later permit specifying 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. Beginning with Shorewall 4.0.6, 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 ::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). 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. Otherwise, unless you are using Shorewall-perl, a separate rule will be generated for each port. Shorewall-perl does not automatically break up lists into individual rules. 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. 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. Otherwise, unless you are using Shorewall-perl, a separate rule will be generated for each port. Shorewall-perl does not automatically break up lists into individual rules.
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 SERVER 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(5). See http://shorewall.net/PortKnocking.html for an example of using an entry in this column with a user-defined action rule. RATE LIMIT (Optional) - [-|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 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 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. This option is only supported by Shorewall-perl. CONNLIMIT - [!]limit[:mask] Added in Shorewall-perl 4.2.1. 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...] Added in Shorewall-perl 4.2.1. 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 , , , , , or monthdays=dd[,dd],... where dd is an ordinal day of the month datestart=yyyy[-mm[-dd[hh[:mm[:ss]]]]] Defines the starting date and time. datestop=yyyy[-mm[-dd[hh[:mm[:ss]]]]] Defines the ending date and time. Restrictions Unless you are using Shorewall-perl and your iptables/kernel have Repeat Match support (see the output of shorewall show capabilities), if you specify a list of DEST PORT(S), then you may not specify SOURCE PORT(S) and vice versa. Example 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(8): #ZONE TYPE OPTIONS fw firewall net ipv4 dmz ipv4 loc ipv4 shorewall-interfaces(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(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 ALSO shorewall(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)