shorewall-rules 5 Configuration Files rules Shorewall rules file /etc/shorewall/rules Entries in this file govern connection establishment by defining exceptions to the policies laid 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 COUNT 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: 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. 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 rule added at the end of this section that invokes the RELATED_DISPOSITION (shorewall.conf(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 and QUEUE. There is an implicit rule added at the end of this section that invokes the INVALID_DISPOSITION (shorewall.conf(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 and QUEUE. There is an implicit rule added at the end of this section that invokes the UNTRACKED_DISPOSITION (shorewall.conf(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. 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 non-blacklisting 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 ALL, ESTABLISHED and RELATED sections must be empty. An except 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. ACCEPT! like ACCEPT but exempts the rule from being suppressed by OPTIMIZE=1 in shorewall.conf(5). action The name of an action declared in shorewall-actions(5) or in /usr/share/shorewall/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_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(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). 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). DNAT- Advanced users only. Like DNAT but only generates the DNAT iptables rule and not the companion ACCEPT rule. DROP Ignore the request. DROP! like DROP but exempts the rule from being suppressed by OPTIMIZE=1 in shorewall.conf(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 a semicolon (';') 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. In this case, you must declare the target as a builtin action in shorewall-actions(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 ';'. IPTABLES({iptables-target [option ...]) 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(5). 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. 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. 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][,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. NFQUEUE[([queuenumber1[,queuenumber2][,bypass]]|bypass)] like NFQUEUE but exempts the rule from being suppressed by OPTIMIZE=1 in shorewall6.conf(5). NONAT Excludes the connection from any subsequent DNAT[-] or REDIRECT[-] rules but doesn't generate a rule to accept the traffic. 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). 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). 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. 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)] 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 http://www.shorewall.net/shorewall_logging.html. 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(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|zone-list[+]|{all|any}[+][-]}[:interface][:{address-or-range[,address-or-range]...[exclusion]|exclusion|+ipset|^countrycode-list} 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. Beginning with Shorewall 4.4.13, you may use a zone-list which consists of a comma-separated list of zones declared in shorewall-zones (5). This zone-list may be optionally followed by "+" to indicate that the rule is to apply to intra-zone traffic as well as inter-zone traffic. 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. Beginning with Shorewall 4.4.13, exclusion is supported -- see see shorewall-exclusion(5). Except when all[+][-] or any[+][-] 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. The above restriction on all[+][-] and any[+][-] is removed in Shorewall-4.4.13. 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. Beginning with Shorewall 4.4.13, exclusion is supported with any -- see see shorewall-exclusion(5). 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. 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 (5). Beginning with Shorewall 4.5.4, A countrycode-list may be specified. A countrycode-list is a comma-separated list of up to 15 two-character ISO-3661 country codes enclosed in square brackets ('[...]') and preceded by a caret ('^'). When a single country code is given, the square brackets may be omitted. A list of country codes supported by Shorewall may be found at http://www.shorewall.net/ISO-3661.html. Specifying a countrycode-list requires GeoIP Match support in your iptables and Kernel. 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 $FW:&eth0 The primary IP address of eth0 in the firewall zone (Shorewall 4.4.17 and later). loc,dmz Both the loc and dmz zones. all!dmz All but the dmz zone. DEST - {zone|zone-list[+]|{all|any}[+][-]}[:{interface|address-or-range[,address-or-range]...[exclusion]|exclusion|+ipset|^countrycode-list}][:port[:random]] Location of Server. May be a zone declared in shorewall-zones(5), $FW to indicate the firewall itself, all. all+ or none. Beginning with Shorewall 4.4.13, you may use a zone-list which consists of a comma-separated list of zones declared in shorewall-zones (5). This zone-list may be optionally followed by "+" to indicate that the rule is to apply to intra-zone traffic as well as inter-zone traffic. Beginning with Shorewall 4.5.4, A countrycode-list may be specified. A countrycode-list is a comma-separated list of up to 15 two-character ISO-3661 country codes enclosed in square brackets ('[...]') and preceded by a caret ('^'). When a single country code is given, the square brackets may be omitted. A list of country codes supported by Shorewall may be found at http://www.shorewall.net/ISO-3661.html. Specifying a countrycode-list requires GeoIP Match support in your iptables and Kernel. 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. Beginning with Shorewall 4.4.13, exclusion is supported -- see see shorewall6-exclusion(5). 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. Except when all[+][-] or any[+][-] 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. 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 4.4.13, exclusion is supported -- see see shorewall-exclusion(5). 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 all[+][-], 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|any}[+]|[-] 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)). Restriction: MAC addresses are not allowed (this is a Netfilter restriction). 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 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 destination bindings to be matched. Only one of the SOURCE and DEST columns may specify an ipset name. 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 (5). 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 modify 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- {-|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 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. 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. 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 (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(5). See http://www.shorewall.net/PortKnocking.html 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. 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 Added in Shorewall 4.4.15. Not used in IPv4 configurations. If you with to supply a value for one of the later columns, enter '-' in this column. 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(5), then any module specified in this column must be listed in the HELPERS setting. 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(5): #ZONE TYPE OPTIONS fw firewall net ipv4 dmz ipv4 loc ipv4 shorewall-interfaces(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(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(5): #ACTION OPTIONS SECCTX builtin /etc/shorewall/rules http://www.shorewall.net/ipsets.html http://www.shorewall.net/configuration_file_basics.htm#Pairs http://www.shorewall.net/shorewall_logging.html shorewall(8), shorewall-accounting(5), shorewall-actions(5), shorewall-blacklist(5), shorewall-blrules(5), shorewall-hosts(5), shorewall_interfaces(5), shorewall-ipsets(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-rtrules(5), shorewall-routestopped(5), shorewall.conf(5), shorewall-secmarks(5), shorewall-tcclasses(5), shorewall-tcdevices(5), shorewall-mangle(5), shorewall-tos(5), shorewall-tunnels(5), shorewall-zones(5)