Hello everybody,
i have got a question about the routing process in iptables. i am currently working on a document for the university wich discribes a little firewall configuration with iptables. i am using the book linux-firewalls from Robert L. Zigler as a reference.

now my question. zigler discribes in his book a dual homed firewall. the interesting thing is, that he discribes that the firewall rules for the FORWARD chain define also the routing of the firewall. so he does not mention any word about ip_forward in /pric/sys/net/....
he says the only the firewall rules make the packets move from one interface to the oher. is that correct so? i searched many forums and howtos on the internet but i did not find anything that gives me a hint that that is correct. i thing ip_forwarding must be active. then it is right what ziegler is writing beause wihout a filter rule the routing from one interface to the oher is forbidden. with the rule it is allowed and so it can be done.

perhabes zigler wrote that because he uses redhat 7.2 as the basic distribution. does anyone know if ip_forward is activated by default on this distribution? that would explain ziegler.

thanks for your support

patrick

in order to route packets ip forwarding must be enabled otherwise no data would be copied from one NIC to another. Nice idea disable routing, secure the login shell and have a proxy to connect to the web (or other ressources) add some INPUT packet filters... ready is poor man's firewall.

Without routing a FORWARD chain would be obsolete - IMHO :-)

read u
o|iver