Using ISA as a Proxy Server in your ASP.NET apps

If the web server your web application or web service is running on is accessing a resource on the outside (a 3rd party web service for example) and it cannot, it could be that the web server your application is running on has an internal IP address. The issue is that it is not being instructed to use ISA as a proxy server. There are a couple of ways of doing this, but one way that has been proven to work is as follows.

The first thing is to change your app's web.config to specify the following section. This should be in a level within the .... Please note that case and spaces are important.


...


usesystemdefault = "false"
proxyaddress="http://YourISAServer:YourPort"
bypassonlocal="true"
/>


...


Once this has been done, you need to tell your Network Admins to setup a rule for allowing your application to pass through the ISA to outside resource. You can either supply them with the URLs of the outside resource or they can monitor the ISA server to see what is being denied. Once the ISA server is configured with the appropriate rules, then you should back in business.