[modauthkerb] Negotiate and SVN clients

[<pe...@bi...>]

I'm trying to setup an SVN server on Redhat 4 using Apache 2.2.6 and 
mod_auth_kerb 5.4.

So far, I'm able to access the SVN repository using Firefox 3.0.7 from a 
Fedora 8 workstation, but I can't seem to get a command line SVN client to 
work from the same workstation.

I've tried a 1.5.5 client I built from source and it reports:

   svn: Negotiate authentication not supported.
   Authentication failed

This binary is using the ra_serf module.  The Apache server log shows:

   ... "OPTIONS https://svn.mycompany.com/svnrepo HTTP/1.1" 401 401 "-" "SVN/1.5.5 (r34862) serf/0.1.2"

I also tried using the Collabnet 1.5.6 Redhat client and it reports:

   svn: OPTIONS of 'https://svn.mycompany.com/svnrepo': authorization failed (https://svn.mycompany.com)

The binary contains both ra_serf and ra_neon modules, but from looking at 
the Apache log it appears to use the ra_neon module:

   ... "OPTIONS /svnrepo HTTP/1.1" 401 401 "-" "SVN/1.5.6 (r36142) neon/0.28.3"

Is there something else I need to configure with the SVN clients?

PS. What about other SVN clients, TortoiseSVN, Eclipse, SVNKit?  I have 
lots of users on different platforms (mostly Mac, Linux, Windows) using 
lots of different SVN clients.  How common is support of Kerberos 
negotiate auth with SVN clients?