"su" from VNC session doesn't work but works ok when at the terminal

lightsp33d · 11-18-2009, 07:26 PM

When I connect to my workstation via Real VNC Viewer 4 to Xvnc running on the workstation, and running "su -" I get authentication failure as follows:

Nov 18 16:24:00 localhost su: pam_unix(su-l:auth): authentication failure; logname=xyz uid=500 euid=0 tty=pts/6 ruser=xyz rhost= user=root

So, effectively I cannot su when connected via VNC.

But if I'm at my workstation, I can su just fine:

Nov 18 16:24:30 localhost su: pam_unix(su-l:session): session opened for user root by xyz(uid=500)

Interestingly enough, I cannot su to my own userid over vnc, i.e.

su xyz

In /var/log/secure I get:

Nov 18 17:23:58 localhost su: pam_unix(su:auth): authentication failure; logname=xyz uid=500 euid=0 tty=pts/6 ruser=xyz rhost= user=xyz

I suspect it has something to do with PAM, but cannot figure it out.

Any help?

lightsp33d · 11-18-2009, 07:50 PM

I'd also like to add that when I'm connected via VNC to my workstation and then ssh to my workstation (ssh xyz@localhost), then I can "su" successfully. So it appears that "su" works fine via ssh, even though the initial connection is via VNC.

exvor · 11-18-2009, 09:24 PM

This might be the same problem people have when trying to su in a X windows session and it does not work. Try adding your userid to the wheel group. For some reason that still escapes me it causes su issues.