shorewall-nesting 5 Nesting Shorewall Nested Zones child-zone[:parent-zone[,parent-zone]...] In shorewall-zones(5), a zone may be declared to be a sub-zone of one or more other zones using the above syntax. Where zones are nested, the CONTINUE policy in shorewall-policy(5) allows hosts that are within multiple zones to be managed under the rules of all of these zones. /etc/shorewall/zones: #ZONE TYPE OPTION fw firewall net ipv4 sam:net ipv4 loc ipv4 /etc/shorewall/interfaces: #ZONE INTERFACE BROADCAST OPTIONS - eth0 detect dhcp,norfc1918 loc eth1 detect /etc/shorewall/hosts: #ZONE HOST(S) OPTIONS net eth0:0.0.0.0/0 sam eth0:206.191.149.197 /etc/shorewall/policy: #SOURCE DEST POLICY LOG LEVEL loc net ACCEPT sam all CONTINUE net all DROP info all all REJECT info The second entry above says that when Sam is the client, connection requests should first be processed under rules where the source zone is sam and if there is no match then the connection request should be treated under rules where the source zone is net. It is important that this policy be listed BEFORE the next policy (net to all). You can have this policy generated for you automatically by using the IMPLICIT_CONTINUE option in shorewall.conf(5). Partial /etc/shorewall/rules: #ACTION SOURCE DEST PROTO DEST PORT(S) ... DNAT sam loc:192.168.1.3 tcp ssh DNAT net loc:192.168.1.5 tcp www ... Given these two rules, Sam can connect to the firewall's internet interface with ssh and the connection request will be forwarded to 192.168.1.3. Like all hosts in the net zone, Sam can connect to the firewall's internet interface on TCP port 80 and the connection request will be forwarded to 192.168.1.5. The order of the rules is not significant. Sometimes it is necessary to suppress port forwarding for a sub-zone. For example, suppose that all hosts can SSH to the firewall and be forwarded to 192.168.1.5 EXCEPT Sam. When Sam connects to the firewall's external IP, he should be connected to the firewall itself. Because of the way that Netfilter is constructed, this requires two rules as follows: #ACTION SOURCE DEST PROTO DEST PORT(S) ... ACCEPT+ sam $FW tcp ssh DNAT net loc:192.168.1.3 tcp ssh ... The first rule allows Sam SSH access to the firewall. The second rule says that any clients from the net zone with the exception of those in the “sam” zone should have their connection port forwarded to 192.168.1.3. If you need to exclude more than one zone, simply use multiple ACCEPT+ rules. This technique also may be used when the ACTION is REDIRECT. /etc/shorewall/zones /etc/shorewall/interfaces /etc/shorewall/hosts /etc/shorewall/policy /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_rules(5), shorewall-routestopped(5), shorewall-rules(5), shorewall.conf(5), shorewall-tcclasses(5), shorewall-tcdevices(5), shorewall-tcrules(5), shorewall-tos(5), shorewall-tunnels(5), shorewall-zones(5)