Environmental Details
Relevant bits of server's /etc/ssh/sshd_config:
X11Forwarding yes
X11DisplayOffset 10
X11UseLocalhost no
Relevant bits of client's $HOME/.ssh/config:
Host *
XAuthLocation /opt/X11/bin/xauth
ForwardX11 yes
ForwardX11Trusted yes
Using XQuartz on macOS High Sierra.
The Problem
I'm spinning up a vagrant Ubuntu 18.04 VM. I've added a second user outside of the vagrant user.
ssh -X vagrant@ubuntu-bionic xclock
I can get X11Forwarding to work when I login as the vagrant user. I cannot get X11Forwarding to work when I login as the ops user.
ssh -X ops@ubuntu-bionic xclock
X11 forwarding request failed on channel 0
Error: Can't open display:
I want to be able to get it to work with the ops user. From the client, $DISPLAY has a value. When I login with vagrant, $DISPLAY has a value. When I login as ops, $DISPLAY is unset. If I set $DISPLAY to match what it is with the vagrant user, I get the same error:
Error: Can't open display: localhost:10.0
when X11UseLocalhost yes
Error: Can't open display: ubuntu-bionic:10.0
when X11UseLocalhost no
If I login as ops and then sudo su - vagrant, $DISPLAY remains unset. If I login as vagrant and then sudo su - ops, $DISPLAY is inherited.
What am I missing to get this to work? I've run xhost + in each user (including sudo -s root xhost +) and it still doesn't work.
If I add -vv to my ssh commands, I see this message when connecting as vagrant:
X11 forwarding request accepted on channel 0
and as ops:
Remote: X11 forwarding disabled in user configuration file.
X11 forwarding request failed on channel 0