You can find out by attempting to connect to the Internet through the proxy using an HTTP request. Follow these instructions:
- Open telnet by going to Start Menu->Run and type telnet.
- Open an connection to the proxy server on the port Internet Explorer uses and past the following HTTP request:
telnet> open address.of.proxy 8080
Code:
GET http://www.google.com/ HTTP/1.0
Host: www.google.com
You should recieve a response which looks something like this:
Code:
HTTP/1.0 407 Proxy Authentication Required
Date: Thu, 20 Oct 2005 22:37:11 GMT
Content-Type: text/html
Content-Length: 1302
Expires: Thu, 20 Oct 2005 22:37:11 GMT
Proxy-Authenticate: Basic realm="Cache name"
Proxy-Connection: close
I have highlighted the line that you interested in. It lists the authentication shcemes that the server supports.
If the server requires NTLM authntication, the PC may need to be a member of the domain and the user authenticated on that domain. This may explain why it works on some PC's and not others.