These clients on the inside network have a NAT translation, but that doesn't necessarily mean that they are allowed access. They now need a rule to allow them to access the outside network (the Internet). That rule will also allow the return traffic to come back in.
To make a rule to allow these users port 80 (Web browsing), you would type this:
PIX1(config)# access-list outbound permit tcp 10.0.0.0 255.0.0.0 any eq 80
PIX1(config)# access-group outbound in interface inside
PIX1(config)#
Note that PIX access lists, unlike router access lists, use a normal subnet mask, not a wildcard mask.
With this access list, you have restricted the inside hosts to accessing Web servers only on the outside network (routers).
PIX firewall configuration
Step 1: The basics
Step 2: Guidelines
Step 3: Configuration setup
Step 4: PIX configuration
Step 5: Network address translation
Step 6: Firewall rules
Step 7: Showing and saving configuration
About the author
David Davis (CCIE #9369, CWNA, MCSE, CISSP, Linux+, CEH) has been in the IT industry for 15 years. Currently, he manages a group of systems/network administrators for a privately owned retail company and authors IT-related material in his spare time. He has written more than 50 articles, eight practice tests and three video courses and has co-authored one book. His Web site is HappyRouter.com.
This tip originally appeared on SearchNetworking.com.
