Question & Answer
Question
Why did X11 forwarding stop working?
SYMPTOMS:
DISPLAY is not set although SSH has X11 forwarding enabled by the following steps:
% stopsrc -s sshd % vi /etc/ssh/sshd_config
Changed:
# X11Forwarding no
To:
X11Forwarding yes
% startsrc -s sshd
However a user connects with SSH X11 forwarding and the DISPLAY is not set:
$ ssh -X <hostname> $ echo $DISPLAY (this is null!!!)
Cause
X11 forwarding was broken in security fix for level 6.0.0.6201 and 7.1.102.1100. This issue was fixed in a later version 6.0.0.6203 and 7.1.101.5000, but that fix was not released in openssh.base.server 7.5.102.1100
Answer
Customers experiencing this SSH X11 forwarding issue should download and install openssh.base.server 7.5.102.1500
https://www-01.ibm.com/marketing/iwm/platform/mrs/assets?source=aixbp&S_PKG=openssh&S_PKG=openssh
RELATED NOTES:
This is addressed in an OpenSSH APAR IV87826
- https://www-01.ibm.com/support/entdocview.wss?uid=isg1IV87826
- The current APAR description is not really clear, since the real issue is that the X11 forwarding does not work, and which is what causes the DISPLAY to be unset.
- The APAR is still listed in open status because the resolving fixes have not yet been provided on an AIX image. The openssh.base images are published more frequently at the AIX Web Download Pack Programs site
- https://www-01.ibm.com/marketing/iwm/platform/mrs/assets?source=aixbp&S_PKG=openssh
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Document Information
Modified date:
13 July 2020
UID
ibm10716755