7.5. DMZs and iptables

Rules can also be set to route traffic to certain machines, such as a dedicated HTTP or FTP server, preferably one that is isolated from the internal network on a de-militarized zone (DMZ). To set a rule for routing all incoming HTTP requests to a dedicated HTTP server at IP address and port 80 (outside of the range of the LAN), network address translation (NAT) calls a PREROUTING table to forward the packets to the proper destination:

iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j DNAT \

With this command, all HTTP connections to port 80 from the outside of the LAN are routed to the HTTP server on a separate network from the rest of the internal network. This form of network segmentation can prove safer than allowing HTTP connections to a machine on the network. If the HTTP server is configured to accept secure connections, then port 443 must be forwarded as well.