I have install XmlRpcPlugin and HttpAuthPlugin, I am not sure, where exactly is the error. when I connect by my .NET client to the XmlRpc?, I get this exception from request.GetResponse?() (.NET method)
I debugged it by fiddler HTTP debugger and I have found, that trac send wrong Content-Length (23bytes). It sends text "Authentication required" which is exactly 23bytes. But there is small HTML block appended, which cause, that content length is wrong. I can reproduce it with python 2.5 and python 2.7 as well. I have attached the output of fiddler, please see bellow. I find interesting, that the request is made via HTTP 1.1, but in repsonse HTTP 0.9 is mentioned.
POST http://10.250.10.55/mew/login/xmlrpc HTTP/1.1
HTTP/1.1 401 Unauthorized
Server: tracd/0.12.2 Python/2.7
Date: Wed, 02 Mar 2011 14:07:38 GMT
WWW-Authenticate: Basic realm="Control Panel"
Expires: Fri, 01 Jan 1999 00:00:00 GMT
<p>Error code 400.
<p>Message: Bad HTTP/0.9 request type ('<?xml').
<p>Error code explanation: 400 = Bad request syntax or unsupported method.