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Problems with chained proxy servers

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11 replies

by tom_a_morris

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Here is my problem. When I was running 1 MS Proxy 2.0 server, with a direct connection to the Internet, I was able to get to all sites, including my intranet site via my browser.

Then I installed a second MS Proxy, but this Proxy is chained to an upstream Proxy located out of state. All works fine on this new Proxy, other than I can no longer get to my intranet site. It gives me a message saying "Host not found".

Both the initial Proxy and the new downstream(chained) proxy use the same DNS servers.

Question: When you are using chained proxy servers, is the name resolution process (DNS)any different than when the proxy servers are not chained?

If not, does anyone have any ideas on why the chained proxy server cannot see myintranet?

Tom Morris

11 replies

by dheupel

The chained proxy server must have two NICs installed, one with the way it set to the downstream, outbound, out-of-state proxy server now, and another NIC with its default gateway address set to the router on the subnet where the upstream in-house proxy server that can see your intranet resides.

Good luck.

by tom_a_morris

Your observations are correct and are in place. Problem still exists.

I assume you are referring to the upstream proxy server needing 2 NIC's. My local downstream chained proxy has only 1 NIC.

by Former member

I'm getting a faint feeling that your gateway information is not quite correct. Somewhere along the way, you have to be sure your routing is working properly through the paths of your proxy servers. I would start testing this by pinging and tracerouting.

by tom_a_morris

Connectivity is not a problem. I can ping throughout. As I said in my post, all other web access works fine via either the standalone or chained proxy. Its just my intranet that is not accessible from the chained proxy. It makes me think it is a name resolution problem, but both proxies access the same DNS server and are on the same LAN segment.

by mckaytech

This doesn't directly answer your question but you can separate out routing(connectivity) issues from name resolution issues by seeing if you can connect to your Intranet using the IP address of the Intranet server (rather than the name). If you can, that confirms it is a DNS issue rather than a routing issue (such as a gateway or subnet mask problem).

If that is the case, I would use nslookup (or download one of the DNS tools packages like Cyberkit) to check the name records on your DNS servers.

paul

by dheupel

I thnk you have misunderstood where I was going with this...

Your downstream chained proxy also requires two NICs.

In your chained proxy, you have your current NIC card that can communicate with the out-of-state proxy server. This is good because it ensure your outbound communications. Place a second NIC in the chained proxy server, and configure it so that its default gateway is either 1) the router that talks directly to your Intranet server, or 2) the Intranet server itself.

Also,enable IP forwarding on the chained proxy server, and double-check any custom packet filters if you have configured any of those.

Good luck.

by Former member

LOL, Now I'm confused. You said: "I can ping throughout, which I stated" (you did not state this) and then you say you get errors like "Host not found" and you say that you cannot access your intranet, which obvious means that you CANNOT ping your intranet, and therefore CANNOT ping it!

Cmon, can you ping your intranet or not? Can you ping names? Can you ping DNS names? Are names resolving and are you being routed to the intranet...This is the whole point I was trying to tell you . Do some troubleshooting and tracing...

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