A firewall is a system that is designed to prevent unauthorizedaccess to private computers or networks. Firewalls can beimplemented in hardware, like the DFL-700, or software, like ZoneAlarm. All data entering or leaving the computer must pass throughthe firewall. The purpose of a firewall is to allow the data youwant to get through, like the web sites you´re looking at, oryour email or the network games you are playing, while keepinghackers out.
Routers use NAT which will act as a firewall. Some of theD-Link routers will have advanced firewall rules to have morecontrol of the incoming and outgoing traffic. You cannot "turn thefirewall off". A way to allow traffic in from the internet is toopen ports or enable DMZ to allow all traffic to 1computer.
By default, all D-Link routers block all incoming ports.