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ssh X11 forwarding with Mepis 8.5

I'm having problems forwarding X11 with my test machine I recently successfully (Other than this issue...) upgraded from Mepis 8.0 to 8.5. It was all working fine before the upgrade and I made sure the sshd_config file I was using was maintained but I keep getting cannot open display and/or cannot connect to server messages when I try to start an app remotely. I can ssh onto the box without issues but the forwarding thing has me stumped. I'm not sure if it's a KDE4 issue or something trivial I've overlooked...

When you connect via ssh, what does 'echo $DISPLAY' show ?

Interestingly enough, it returns nothing! I logged in using ssh -XC user@host and echo $DISPLAY resulted in a blank line followed by my command prompt being displayed again.

Just posted this on MepisLovers.

I think I might be onto something... I added -v to an attempt to ssh onto my machine. Amongst the debug was a line that said no xauth program. After a bit of Googling, I found that sshd looks for xauth in /usr/bin/X11/xauth. The thing is, xauth seems to be there... Any thoughts?

Maybe /etc/ssh/sshd_config no longer has 'X11Forwarding yes' after your upgrade ...

It's not that. Here's my sshd_config.

Code:

#      $OpenBSD: sshd_config,v 1.38 2001/04/15 21:41:29 deraadt Exp $



# This sshd was compiled with PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin



# This is the sshd server system-wide configuration file.  See sshd(8)

# for more information.



Port 22

#Protocol 2,1

#ListenAddress 0.0.0.0

#ListenAddress ::

HostKey /etc/ssh/ssh_host_key

HostKey /etc/ssh/ssh_host_rsa_key

HostKey /etc/ssh/ssh_host_dsa_key

ServerKeyBits 768

LoginGraceTime 600

KeyRegenerationInterval 3600

PermitRootLogin no

AllowUsers sshl0gin rich@192.168.1.*

#

# Don't read ~/.rhosts and ~/.shosts files

IgnoreRhosts yes

# Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication

#IgnoreUserKnownHosts yes

StrictModes yes

X11Forwarding yes

X11DisplayOffset 10

PrintMotd no

PrintLastLog no

TCPKeepAlive yes



# Logging

SyslogFacility AUTH

LogLevel INFO

#obsoletes QuietMode and FascistLogging



#RhostsAuthentication no

#

# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts

RhostsRSAAuthentication no

# similar for protocol version 2

HostbasedAuthentication no

#

RSAAuthentication yes



# To disable tunneled clear text passwords, change to no here!

PasswordAuthentication yes

PermitEmptyPasswords no



# Uncomment to disable s/key passwords

#ChallengeResponseAuthentication no



# Uncomment to enable PAM keyboard-interactive authentication

# Warning: enabling this may bypass the setting of 'PasswordAuthentication'

#PAMAuthenticationViaKbdInt yes



# To change Kerberos options

# NB: Debian's ssh ships without Kerberos Support

#KerberosAuthentication no

#KerberosOrLocalPasswd yes

#AFSTokenPassing no

#KerberosTicketCleanup no



# Kerberos TGT Passing does only work with the AFS kaserver

#KerberosTgtPassing yes



#CheckMail yes

#UseLogin no



#MaxStartups 10:30:60

Banner /home/shared/banner

#ReverseMappingCheck yes



Subsystem sftp /usr/lib/openssh/sftp-server

UsePAM yes



DenyUsers onthego

Interesting ... running strings against mine indicates it looks in /usr/bin :

Code:

# strings /usr/sbin/sshd | grep xauth

/usr/bin/xauth

xauthlocation

maxauthtries

No xauth program; cannot forward with spoofing.

# which xauth

/usr/bin/xauth

According to the sshd_config man page:

Quote:

XAuthLocation
Specifies the full pathname of the xauth(1) program. The default
is /usr/bin/xauth.

hth

I now think that it's an issue of ssh not being able to set DISPLAY. Any thoughts on how I can diagnose exactly where the problem lies?

Try running sshd with the '-d' flag, this should provide enough output to troubleshoot with

I cracked it!!!

After much Googling, I added:

Code:

AddressFamily inet

to sshd_config in order to disable ipv6 and X11 forwarding now seems to work!

I wonder if the need for this is something to do with the kernel upgrade I did as part of the 8.0 to 8.5 upgrade...?