16
Firewall
This chapter introduces the ZyWALL’s firewall and shows you how to configure your ZyWALL’s firewall.
16.1 Firewall Overview
The ZyWALL’s firewall is a stateful inspection firewall. The ZyWALL restricts access by screening data packets against defined access rules. It can also inspect sessions. For example, traffic from one zone is not allowed unless it is initiated by a computer in another zone first.
A zone is a group of interfaces or VPN tunnels. Group the ZyWALL’s interfaces into different zones based on your needs. You can configure firewall rules for data passing between zones or even between interfaces and/or VPN tunnels in a zone.
This example shows the ZyWALL’s default firewall behavior for WAN to LAN traffic and how stateful inspection works. A LAN user can initiate a Telnet session from within the LAN zone and the firewall allows the response. However, the firewall blocks Telnet traffic initiated from the WAN zone and destined for the LAN zone. The firewall allows VPN traffic between any of the networks.
Figure 18 Default Firewall Action
LAN | WAN |
Your customized rules take precedence and override the ZyWALL’s default settings. The ZyWALL checks the schedule, user name (user’s login name on the ZyWALL), source IP address, destination IP address and IP protocol type of network traffic against the firewall rules (in the order you list them). When the traffic matches a rule, the ZyWALL takes the action specified in the rule.
For example, if you want to allow a specific user from any computer to access one zone by logging in to the ZyWALL, you can set up a rule based on the user name only. If you also apply a schedule to the firewall rule, the user can only access the network at the scheduled time. A
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