If your ISP has you defined as a single user connection (only 1 IP address) then you need to fake the ISP out by using Masquerading. This causes all traffic from your inside network to appear to come from the linux machine itself. If you don't use masquerading, the ISP doesn't know to route the responses back to your machine. You also need to make sure you have IP forwarding on. I have a similar network here. 9 PCs on the inside that connect to the ISP through a single IP address. I'm am running RedHat 6.2, which used ipchains instead of iptables so I can't give you any specifics. There is a howto on masquerading. I'd be glad to answer any questions you have. > Philip Denny wrote: > > I just discovered the Linux User Group on the web. I am looking for > Linux assistance to solve a problem. I am new to Linux/Unix but after > using for about 6 months, I can see that it is great OS. Can you > recommend one of your members or a student to help me solve what I > believe is a small problem. I am attempting to setup iptables on > Redhat 7.2. The Linux box will be placed in front of a 4 node > windows network. I an able to ping both the inside and outside network > card from any of my windows PCs. But I can't ping anything on the > internet from inside. I can also surf the web from the linux box. I > have down loaded gShield and attempted to install. > > What am I doing wrong? > > Philip