Having a rather difficult to fathom problem with a user logging into some external Outlook WebAccess webmail server. I've read a bunch of posts about the problems with NTLM and Squid <= 2.5, but this one is stumping me. A little bit about our setup -- using multiple squid and dg boxes and a WCCP router to transparently cache/filter the web. Most of our squid caches are 2.6, but we still have two remaining that are version 2.5 that we're phasing out. The odd thing is, the login seems to work correctly with squid 2.5 and incorrectly with 2.6, which is exactly backwards of what I expect. When I proxy directly to one of the squid 2.6 boxes, specifically: Squid Cache: Version 2.6.STABLE18 configure options: '--prefix=/usr' '--sysconfdir=/etc/squid' '--bindir=/usr/sbin' '--sbindir=/usr/sbin' '--localstatedir=/var' '--libexecdir=/usr/sbin' '--datadir=/usr/share/squid' '--mandir=/usr/share/man' '--with-maxfd=4096' '--disable-useragent-log' '--enable-ssl' '--with-openssl' '--disable-ident-lookups' '--enable-poll' '--enable-truncate' '--enable-gnuregex' '--enable-async-io' '--with-pthreads' '--with-aio' '--with-dl' '--enable-storeio=aufs,diskd,ufs,coss,null' '--enable-removal-policies=heap,lru' '--enable-kill-parent-hack' '--enable-forw-via-db' '--enable-linux-netfilter' '--enable-underscores' '--enable-x-accelerator-vary' I get a login box (in firefox) that reads: Enter username and password for "" at http://mail.example.com When I put in the credentials and click OK, the box just keeps coming back. When I click cancel, I get a different login box: Enter username and password for "mail.example.com" at http://mail.example.com and the login works. If I proxy directly to one of the 2.5 boxes: Squid Cache: Version 2.5.STABLE4 configure options: --disable-useragent-log --enable-ssl --with-openssl --disable-ident-lookups --enable-poll --enable-truncate --enable-gnuregex --enable-async-io --with-pthreads --with-aio --with-dl --enable-storeio=aufs,diskd,ufs,coss,null --enable-removal-policies=heap,lru --enable-kill-parent-hack --enable-forw-via-db --enable-linux-netfilter --enable-underscores --enable-x-accelerator-vary It goes directly to the second login box. Any thoughts? Any information I can provide to be helpful? Sean