The ssh client and sshd server have incorrect paths to xauth hardcoded into tme. This breaks X11 forwarding on PPC clients and servers. This package needs to be rebuilt with the correct paths (probably just matter of running ./configure.) Until then, a work around is to set, in your system-wide /etc/ssh/ssh_config:
XAuthLocation /usr/bin/xauth
and the same in /etc/ssh/sshd_config Here's the results of dumping the strings from ssh looking for xauth.
$ strings /usr/bin/ssh | grep xauth /usr/X11R6/bin/xauth xauthlocation No xauth program. %s/xauthfile Warning: No xauth data; using fake authentication data for X11 forwarding.
and here's the same process on the sshd binary:
$ strings /usr/sbin/sshd | grep xauth /usr/X11R6/bin/xauth xauthlocation maxauthtries No xauth program; cannot forward with spoofing.
The correct path for the xauth binary is /usr/bin/xauth. The package version effected is 4.6p1-3, which at the time of this writing is the version in the package db. Matthew Cox