ssh + x11 forwarding not working on BLFS

ordealbyfire83 · 05-22-2018, 10:17 PM

Like the title says I have not been able to get X forwarding working for the case that BLFS is acting as the server. I have verified that:

X was installed when ssh was compiled
X11Forwarding is set to 'yes' in /etc/ssh/sshd.conf
The port used by ssh is opened in iptables

and I get the following when running "ssh -p <port> -Y user@ipaddress"

Code:

X11 forwarding request failed on channel 0

but I do get logged in. This message seems not to why it failed. I get this with BLFS versions 8.2, 7.9, and 7.5 acting as the server, so something must be missing. Any suggestions?

ordealbyfire83 · 05-24-2018, 07:28 PM

Well after running ssh in verbose mode it seems it cannot find 'xauth.' For stock BLFS installations this is in /usr/bin - seems pretty straightforward. But not straightforward is a seemingly undocumented sshd option -

After adding

Code:

XAuthLocation /usr/bin/xauth

to /etc/ssh/sshd_config, it finally works.

In verbose mode it still warns me that xauth isn't found, which probably indicates that ssh is looking somewhere else first and then parsing the config file.

I'd hardly call this a 'solution' because an out-of-the-box installation shouldn't require "undocumented" options. I've never had to do this for any other distribution in the past.

Keith Hedger · 05-30-2018, 07:02 AM

See this:

Code:

--with-xauth=/usr/bin/xauth: Set the default location for the xauth binary for X authentication. Change the location if xauth will be installed to a different path. This can also be controlled from sshd_config with the XAuthLocation keyword. You can omit this switch if Xorg is already installed.

At the bottom of the openssh page here:

http://www.linuxfromscratch.org/blfs...s/openssh.html