When IPv6 is enabled on a Linux system, ALL inbound remote logins using IPv4 to kdm fail with an error message( when kdm debugging turned on ) stating: "ConvertAddr returning -1 for family 10." This causes the ~/.Xauthority file to not be able to be updated, which causes the login to be denied. Without kdm debugging turned on the error manifiests itself in the system log as: "can't update authorization file in home dir /home/myhomedir" I took a peek at the KDE source code( both 3.1.5 and 3.2 ) and noticed that the function ConvertAddr doesn't handle IPv6 at all. Specifically, inbound IPv4 addrs get mapped to IPv6 addrs, and are then passed to ConvertAddr(). To workaround the problem X has to be emerged with USE='-ipv6'( to get around a similar problem with XFS ) and IPv6 support in the kernel disabled. Then everything works fine. Reproducible: Always Steps to Reproduce: 1. Setup KDM to allow remote logins. 2. Emerge X with ipv6 support. 3. Have a kernel that supports IPv6 4. Start kdm with the command line "kdm debug 1" 5. Attempt a remote login( I was using Cygwin/X so XWin32.exe -query KDM_MACHINE_IP -fp XFS_MACHINE_IP ). See additional information about notes regarding XFS. 6. Look at the system log. There is a bug with XFS( X Font Server, not the filesystem ) that requires kernel IPv6 support to be loaded if X was emerged with IPv6 support. Otherwise XFS won't accept remote connections. This makes testing kind of hairy. I'll file a seperate bug on this issue.
Regarding XFS: There is already a similar bug filed against XFree in general: http://bugs.gentoo.org/show_bug.cgi?id=22517
Please file a bug report at bugs.kde.org as it's an upstream issue.
Filed with KDE bug tracker. ID# 75238. http://bugs.kde.org/show_bug.cgi?id=75238
