Xclock Error: Can't open display: - after upgrading to openSSH 5.2p1

Question

I have got two servers apssvrX and apssvrZ on OEL. Both were built by the same team using their standard build scripts.
Having received the servers I had installed Oracle (ODI) product on it successfully.
Then as a part of requirement and as per Oracle support's advise, I had upgraded the ssh version on apssvrX server from OpenSSH_4.3p2 To OpenSSH_5.2p1, so that, I can implement the chroot jailing.
As per Oracle advise, I had downloaded the 3 RPMs from "_http://layer1.rack911.com/openssh/rhel5/x86_64/" to run them on my first server i.e., apssvrX and then configured the sshd services following the below steps:
a) Modify /etc/ssh/sshd_config to comment the below line:
#Subsystem sftp /usr/libexec/openssh/sftp-server
b) Add below lines:
Subsystem sftp internal-sftp
Match Group sftponly
ChrootDirectory %h
X11Forwarding no
AllowTcpForwarding no
ForceCommand internal-sftp
Then lastly, Restart sshd services complete the configuration
# /etc/init.d/sshd restart
apssvrX server current details are as below:
apssvrX$ uname -a
Linux apssvrX 2.6.18-128.el5 #1 SMP Wed Jan 21 08:45:05 EST 2009 x86_64 x86_64 x86_64 GNU/Linux
apssvrX$ ssh -V
OpenSSH_5.2p1, OpenSSL 0.9.8e-fips-rhel5 01 Jul 2008
My problems started from this point onwards. I want to install another Oracle product using OUI, but when I try to execute xclock using the Exceed HummingBird tool on apssvrX server then it fails with the error - (xclock) Error: Can't open display:
I tried the DISPLAY variable setup as well but to no use.
Whereas I can successfully execute the xclock on apssvrZ and OUI as well. Its config details are as below:
apssvrZ$ uname -a
Linux apssvrZ 2.6.18-128.el5 #1 SMP Wed Jan 21 08:45:05 EST 2009 x86_64 x86_64 x86_64 GNU/Linux
apssvrZ$ ssh -V
OpenSSH_4.3p2, OpenSSL 0.9.8e-fips-rhel5 01 Jul 2008
Please advise the way forward.

Answer 1

Tried but still same error.
Affected servers's sshd_config is as below:
[root@apssvrX]# cat /etc/ssh/sshd_config
# $OpenBSD: sshd_config,v 1.73 2005/12/06 22:38:28 reyk Exp $
# This is the sshd server system-wide configuration file. See
# sshd_config(5) for more information.
# This sshd was compiled with PATH=/usr/local/bin:/bin:/usr/bin
# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented. Uncommented options change a
# default value.
#Port 22
Protocol 2
Protocol 2
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::
# HostKey for protocol version 1
#HostKey /etc/ssh/ssh_host_key
# HostKeys for protocol version 2
#HostKey /etc/ssh/ssh_host_rsa_key
#HostKey /etc/ssh/ssh_host_dsa_key
# Lifetime and size of ephemeral version 1 server key
#KeyRegenerationInterval 1h
#ServerKeyBits 768
# Logging
# obsoletes QuietMode and FascistLogging
#SyslogFacility AUTH
SyslogFacility AUTHPRIV
#LogLevel INFO
# Authentication:
#LoginGraceTime 2m
PermitRootLogin without-password
#StrictModes yes
#MaxAuthTries 6
#RSAAuthentication yes
#PubkeyAuthentication yes
#AuthorizedKeysFile .ssh/authorized_keys
# 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
# Change to yes if you don't trust ~/.ssh/known_hosts for
# RhostsRSAAuthentication and HostbasedAuthentication
#IgnoreUserKnownHosts no
# Don't read the user's ~/.rhosts and ~/.shosts files
#IgnoreRhosts yes
# To disable tunneled clear text passwords, change to no here!
#PasswordAuthentication yes
#PermitEmptyPasswords no
PasswordAuthentication yes
# Change to no to disable s/key passwords
#ChallengeResponseAuthentication yes
ChallengeResponseAuthentication no
# Kerberos options
#KerberosAuthentication no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes
#KerberosGetAFSToken no
# GSSAPI options
#GSSAPIAuthentication no
GSSAPIAuthentication yes
#GSSAPICleanupCredentials yes
GSSAPICleanupCredentials yes
# Set this to 'yes' to enable PAM authentication, account processing,
# and session processing. If this is enabled, PAM authentication will
# be allowed through the ChallengeResponseAuthentication mechanism.
# Depending on your PAM configuration, this may bypass the setting of
# PasswordAuthentication, PermitEmptyPasswords, and
# "PermitRootLogin without-password". If you just want the PAM account and
# session checks to run without PAM authentication, then enable this but set
# ChallengeResponseAuthentication=no
#UsePAM no
UsePAM yes
# Accept locale-related environment variables
AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES
AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT
AcceptEnv LC_IDENTIFICATION LC_ALL
#AllowTcpForwarding yes
#GatewayPorts no
#X11Forwarding no
X11Forwarding yes
#X11DisplayOffset 10
#X11UseLocalhost yes
#PrintMotd yes
#PrintLastLog yes
#TCPKeepAlive yes
#UseLogin no
#UsePrivilegeSeparation yes
#PermitUserEnvironment no
#Compression delayed
#ClientAliveInterval 0
#ClientAliveCountMax 3
#ShowPatchLevel no
#UseDNS yes
#PidFile /var/run/sshd.pid
#MaxStartups 10
#PermitTunnel no
# no default banner path
#Banner /some/path
# override default of no subsystems
Subsystem sftp /usr/libexec/openssh/sftp-server
## Commented the sftp jailing configuration
##Subsystem sftp internal-sftp
##Match Group sftponly
## ChrootDirectory %h
## X11Forwarding no
## AllowTcpForwarding no
## ForceCommand internal-sftp