Linux Firewalls, Third Edition

Converting the Gateway from Local Services to Forwarding

The gateway firewall from Chapter 4 needs some further adjustments to its rules. The services that had been hosted on the gateway have moved to the DMZ. This chapter has shown the forwarding rules on at least one of the two firewalls when the rules were the same, and on both firewalls when the respective rules were a bit different. I don't want to be unnecessarily repetitive and belabor the rules on the gateway.

In the interests of space and patience, yours and mine, the modified prelude to the example from Chapter 4 is not presented here. The modifications are simply to convert the error-checking rules from the local INPUT and OUTPUT chains to the FORWARD chain because the local services ...