ZyWALL 5/35/70 Series User’s Guide
Any protocol that operates in this way must be supported on a
10.6 Guidelines For Enhancing Security With Your Firewall
1Change the default password via SMT or web configurator.
2Think about access control before you connect a console port to the network in any way, including attaching a modem to the port. Be aware that a break on the console port might give unauthorized individuals total control of the firewall, even with access control configured.
3Limit who can telnet into your router.
4Don't enable any local service (such as SNMP or NTP) that you don't use. Any enabled service could present a potential security risk. A determined hacker might be able to find creative ways to misuse the enabled services to access the firewall or the network.
5For local services that are enabled, protect against misuse. Protect by configuring the services to communicate only with specific peers, and protect by configuring rules to block packets for the services at specific interfaces.
6Protect against IP spoofing by making sure the firewall is active.
7Keep the firewall in a secured (locked) room.
10.7Packet Filtering Vs Firewall
Below are some comparisons between the ZyWALL’s filtering and firewall functions.
10.7.1Packet Filtering:
•The router filters packets as they pass through the router’s interface according to the filter rules you designed.
•Packet filtering is a powerful tool, yet can be complex to configure and maintain, especially if you need a chain of rules to filter a service.
•Packet filtering only checks the header portion of an IP packet.
10.7.1.1 When To Use Filtering
1To block/allow LAN packets by their MAC addresses.
2To block/allow special IP packets which are neither TCP nor UDP, nor ICMP packets.
3To block/allow both inbound (WAN to LAN) and outbound (LAN to WAN) traffic between the specific inside host/network "A" and outside host/network "B". If the filter blocks the traffic from A to B, it also blocks the traffic from B to A. Filters cannot distinguish traffic originating from an inside host or an outside host by IP address.
4To block/allow IP trace route.
Chapter 10 Firewalls | 208 |