Bug 1662189

Summary:	ssh is failing to export the display variable when configured vi /etc/sysctl.conf
Product:	Red Hat Enterprise Linux 8	Reporter:	vinay <vchoudha>
Component:	openssh	Assignee:	Jakub Jelen <jjelen>
Status:	CLOSED ERRATA	QA Contact:	Ondrej Moriš <omoris>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	8.1	CC:	omoris, riehecky, szidek, vpakolu
Target Milestone:	rc	Keywords:	Triaged
Target Release:	8.0	Flags:	jruemker: mirror+
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	openssh-8.0p1-5.el8	Doc Type:	Bug Fix
Doc Text:	Cause: Bug in X11 display binding when IPv6 is disabled. Consequence: The X11 forwarding was failing if IPv6 was disabled. Fix: The ssh no longer fails if the (IPv6) address is not available. Result: SSH is able to initialize X11 forwarding in networks where IPv6 is disabled.	Story Points:	---
Clone Of:	1489013	Environment:
Last Closed:	2020-11-04 01:31:59 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1489013
Bug Blocks:	1594286, 1679810

Comment 14 Ondrej Moriš 2020-04-02 10:42:45 UTC

Successfully reproduced and verified.

OLD (openssh-8.0p1-4.el8_1)
===========================
$ ssh -X root.lab.eng.bos.redhat.com
X11 forwarding request failed on channel 0

# sysctl -a | grep disable_ipv6
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.ens3.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1
net.ipv6.conf.virbr0.disable_ipv6 = 1
net.ipv6.conf.virbr0-nic.disable_ipv6 = 1

# echo $DISPLAY

# xterm 
Warning: This program is an suid-root program or is being run by the root user.
The full text of the error or warning message cannot be safely formatted
in this environment. You may get a more descriptive message by running the
program as a non-root user or by removing the suid bit on the executable.
xterm: Xt error: Can't open display: %s
xterm: DISPLAY is not set

# netstat --numeric-ports | grep localhost

NEW (openssh-8.0p1-5.el8)
=========================
$ ssh -X root.lab.eng.bos.redhat.com

# sysctl -a | grep disable_ipv6
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.ens3.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1
net.ipv6.conf.virbr0.disable_ipv6 = 1
net.ipv6.conf.virbr0-nic.disable_ipv6 = 1

# echo $DISPLAY
localhost:10.0

# xterm 
xterm: cannot load font "-Misc-Fixed-medium-R-*-*-13-120-75-75-C-120-ISO10646-1"
xterm: cannot load font "-misc-fixed-medium-r-semicondensed--13-120-75-75-c-60-iso10646-1"
<running>

# netstat --numeric-ports | grep localhost
tcp        0      0 localhost:6010          localhost:35032         ESTABLISHED
tcp        0      0 localhost:35032         localhost:6010          ESTABLISHED

Comment 17 errata-xmlrpc 2020-11-04 01:31:59 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (openssh bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2020:4439