When you are behind a proxy that uses NTLM authentication, many applications will refuse to work. What is worse, some applications don’t even support passing a name and password to the proxy.

As an example, I take BlogJet. BlogJet supports proxies and authentication. In fact, version 1.6 should support proxies that support NTLM and even Digest. But I could not get it to work with an upstream ISA server.

To get an application like that to work anyway, use NTLMAPS. NTLMAPS stands for NTLM Authorization Proxy Server. Basically, it is a proxy server that you install on your local machine. When you configure an application like BlogJet to use your local machine and the port that NTLMAPPS listens on, NTLMAPPS will take the (anonymous) request from the application and then pass it on to the upstream proxy servers using NTLM authentication with a name and password.

NTLMAPPS comes with a configuration file (server.cfg) where you have to configure the upstream proxy name, port, user name and password. If you don’t type the password, NTLMAPPS will ask it during start. You can also configure the user-agent string so the request looks like it is coming from Internet Explorer 6 or anything you want.

Configuration in BlogJet:

Now, whenever BlogJet needs to connect to the Internet, it will connect to NTLMAPPS on 5865. In turn, NTLMAPPS will connect to the upstream proxy you configured in server.cfg.

NTLMAPPS itself is written in Python, so you will need to install Python on your local machine. It is a great solution to allow any application that can use a proxy to work through MS Proxy or ISA Server.