shorewall-rules 5 rules Shorewall rules file /etc/shorewall/rules Rules in this file govern connection establishment. 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 match is the one that determines the disposition of the request. In most places where an IP address or subnet is allowed, you can preceed the address/subnet with "!" (e.g., !192.168.1.0/24) to indicate that the rule matches all addresses except the address/subnet given. Notice that no white space is permitted between "!" and the address/subnet. 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 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 I suggest 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. The columns in the file are as follows. ACTION Must be one of the following. ACCEPT Allow the connection request. ACCEPT+ like ACCEPT but also excludes the connection from any subsequent DNAT[-] or REDIRECT[-] rules 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. REJECT disallow the request and return an icmp-unreachable or an RST packet. 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. 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 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), this connection request will be passed to the rules defined for that (those) zone(s). LOG Simply log the packet and continue. QUEUE Queue the packet to a user-space application such as ftwall (http://p2pwall.sf.net). COMMENT the rest of the line will be attached as a comment to the Netfilter rule(s) generated by the following entres. 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 defined in shorewall-actions(5) or in /usr/share/shorewall/actions.std. macro The name of a macro defined in a file named 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 "/" and the action (ACCEPT, DROP, REJECT, ...) to be substituted for the parameter. Example: FTP/ACCEPT. 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. If the ACTION names an action defined 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 (must be in upper case) as a log level.This will log to the ULOG target for routing to a separate log through use of ulogd (http://www.gnumonks.org/projects/ulogd). Actions specifying logging may be followed by a log tag (a string of alphanumeric characters) are 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 Source hosts to which the rule applies. May be a zone defined 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 subnets and/or hosts by appending ":" and a comma-separated list of subnets and/or hosts. Hosts may be specified by IP or MAC address; mac addresses must begin with "~" and must use "-" as a separator. Hosts may be specified as an IP address range using the syntax lowaddress-highaddress. This requires that your kernel and iptables contain iprange match support. 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 source bindings to be matched. 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. 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). DEST Location of Server. May be a zone defined 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. Except when all[+] is specified, the server may be further restricted to a particular subnet, host or interface by appending ":" and the subnet, host or interface. See above. Restrictions: 1. MAC addresses are not allowed. 2. In DNAT rules, only IP addresses are allowed; no FQDNs or subnet addresses are permitted. 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: 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 number MUST be specified as an integer and not as a name from services(5). if the ACTION is REDIRECT, this column needs only to contain the port number on the firewall that the request should be redirected to. PROTO (Optional) Protocol - Must be tcp, tcp:syn, udp, icmp, ipp2p, ipp2p:udp, ipp2p:all a number, or all. 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) 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, a separate rule will be generated for each port. SOURCE PORT(S) (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. Unless you really understand TCP/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, a separate rule will be generated for each port. ORIGINAL DEST (Optional) If ACTION is DNAT[-] or REDIRECT[-] then if included and different from the IP address given in the SERVER column, this is an address on some interface on the firewall and connections to 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 usually 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 "!" 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 "!". 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) You may rate-limit the rule by placing a value in this column: rate/interval[:burst] where 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) This column may only be non-empty if the SOURCE is the firewall itself. The column may contain: [!][user name or number][:group name or number][+program name] 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. 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 ACCEPT net loc:192.168.1.3:22 tcp 2222 /etc/shorewall/rules 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_routes(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)