Can someone tell me what is the best and easiest way to give the users on your LAN internet access where the server (2003) is the gateway, not the router? This way I'm protected by the firewall on the server.

I know I can use Routing and Remote Access or a Proxy server but is there another way?

I used to have it set up where for my lan users I'd force them to use my server as their gateway and dns and the server would forward dns requests through my ISP's dns. But I guess it's not returning these requests back to the lan users now.

I'd rather not use a proxy as I want the users to have unrestricted internet access where ftp'ing, telnetting and p2p sharing works. If I use a proxy then I'd have to keep updating its configuration to allow all the ports necessary for them to be able to do all that.

Unfortunately, since reinstalling the server I can't manage to figure out how I did that before as it's not working now.

I set my ISP's DNS as a forwarder in Win'2003.

The setup looks like this:

Win'2003:

IP: 192.168.1.100
Gateway: 192.168.1.1 (router)
DNS: 192.168.1.100

LAN:

IP: via DHCP
Gateway: 192.168.1.1
DNS: 192.168.1.1

Can they not get internet access with this method?

You gave them the wrong ip for dns. It needs to be your dns server 192.168.1.100. This should be the only alteration you have to make to dhcp since you state you have the isp dns in the forwarders tab.

wksts need to point to your dns server. dns then handles the forwarding of name resolution requests to the isps dns server.

I think you went a little haywire because of this "This way I'm protected by the firewall on the server." You are setting up dns the correct way and this has nothing to do with proxy's, or firewall on the server [hardware is always better than software]

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