Security 9-31
Output filter 1: This filter forwards all outgoing traffic to make sure that no outgoing connections from the LAN are blocked.
Basic Firewall is suitable for a LAN containing only client hosts that want to access servers on the WAN, but not for a LAN containing servers providing services to clients on the WAN. Basic Firewall’s general strategy is to explicitly forward
A more complicated filter set would be required to provide WAN access to a
Possible modifications
You can modify the sample filter set Basic Firewall to allow incoming traffic using the examples below. These modifications are not intended to be combined. Each modification is to be the only one used with Basic Firewall.
The results of combining filter set modifications can be difficult to predict. It is recommended that you take special care if you are making more than one modification to the sample filter set.
Trusted host. To allow unlimited access by a trusted remote host with the IP address a.b.c.d (corresponding to a numbered IP address such as 163.176.8.243), insert the following input filter ahead of the current input filter 1:
•Enabled: Yes
•Forward: Yes
•Source IP Address: a.b.c.d
•Source IP Address Mask: 255.255.255.255
•Dest. IP Address: 0.0.0.0
•Dest. IP Address Mask: 0.0.0.0
•Protocol Type: 0
Trusted subnet. To allow unlimited access by a trusted remote subnet with subnet address a.b.c.d (corresponding to a numbered IP address such as 163.176.8.0) and subnet mask e.f.g.h (corresponding to a numbered IP mask such as 255.255.255.0), insert the following input filter ahead of the current input filter 1:
•Enabled: Yes
•Forward: Yes
•Source IP Address: a.b.c.d
•Source IP Address Mask: e.f.g.h
•Dest. IP Address: 0.0.0.0
•Dest. IP Address Mask: 0.0.0.0
•Protocol Type: 0
