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Wierd Proxy Exception issue

Last response: in Networking
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October 8, 2007 9:58:25 AM

I'm getting some weird proxy issues.

I'm trying to access an application at another company, which is connected via a VPN tunnel. It should not pass through the proxy server at my company.

If I add the hostname and the ip address into the proxy exceptions in IE, then it cannot access the application, coming up with a dns_server_failure error using the hostname, and a tcp_error using the IP address.

If I skip the proxy entirely, it can access the application.

I'd have expected the two actions to be functionally identical, so what might be going wrong ?

Thanks,
Chris
October 9, 2007 2:44:17 PM

Another company is connected to your company via VPN?

Your proxy is rerouting outside the VPN because its only recognizing a one way tunnel. When your request goes out, it his your proxy which then forwards the request on somewhere else. When you remove your proxy your request goes wherever, which is why I imagine that works.

Possibly, the other application computer isn't being registered in your DNS because its not setup to. Creating a static entry may resolve this.

I imagine if you use the IP address over the name (http://applicationserver.com = http://10.1.1.100) it may work.
October 9, 2007 2:50:17 PM

riser said:
Another company is connected to your company via VPN?


Yes

Your proxy is rerouting outside the VPN because its only recognizing a one way tunnel. When your request goes out, it his your proxy which then forwards the request on somewhere else. When you remove your proxy your request goes wherever, which is why I imagine that works.
said:
Your proxy is rerouting outside the VPN because its only recognizing a one way tunnel. When your request goes out, it his your proxy which then forwards the request on somewhere else. When you remove your proxy your request goes wherever, which is why I imagine that works.


The question is, why is it going to the proxy, when it is listed in the proxy exceptions, which should mean it doesn't.


Possibly, the other application computer isn't being registered in your DNS because its not setup to. Creating a static entry may resolve this.

I imagine if you use the IP address over the name (http://applicationserver.com = http://10.1.1.100) it may work. said:

Possibly, the other application computer isn't being registered in your DNS because its not setup to. Creating a static entry may resolve this.

I imagine if you use the IP address over the name (http://applicationserver.com = http://10.1.1.100) it may work.


As I stated, the IP address doesn't work when using the proxy (and with the proxy exceptions in place), but does when the proxy is disabled, so it doesn't look like a DNS error, although that is what it is reporting. It isn't the first time I've had DNS error reported in the browser, whilst nslookup works perfectly on the same address. I'm starting to wonder if IE uses some other method somehow.

Chris
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October 9, 2007 5:36:16 PM

Are you accessing a web based application?

Make sure you have multiple entries for the proxy exception; Http://, IP address, just the name, etc.

Are you sure you have the correct address in there? Its not being changed to a different name/IP when you first go to it?
October 10, 2007 9:44:26 AM

riser said:
Are you accessing a web based application?

Make sure you have multiple entries for the proxy exception; Http://, IP address, just the name, etc.

Are you sure you have the correct address in there? Its not being changed to a different name/IP when you first go to it?


Well, trying to access one !

I turned on success monitoring on the firewall, so I could see the traffic passing. When I don't use a proxy, it only goes to that particular IP address, so it's not a wrong address. When I use a proxy with that IP address specified as an exception, it only goes to the proxy, and never tries the IP address directly. Other exceptions in the proxy do not seem to have the same behaviour.

Chris
October 10, 2007 1:32:18 PM

Can you add that exception in your router at work? Or DNS?

Are you using WINS?
!