I've been doing a lot of reading on this... I've got the proxy working in either of these two modes: 1) As a browser configuration proxy 2) with http_port 3128 transparent, in redirected mode I've got NTLM authentication working just fine with #1 above. However, with #2 I never get a password prompt. I don't really care about transparency; I just want to authenticate users that are outbound without having to configure their browser. I asked this question a couple of months back and there are people stating that they are doing the authentication with transparent mode. Some of the references I've found in my searches also seem to corroborate the possibility of this working (but it's not working for me). However, in the documentation it seems that this should not be possible. Am I barking up the wrong tree or is this truly possible? Thanks Scott