Discrepancy in $DISPLAY configuration required to get X to work over SSH
putty, ssh, x11, xming
Solution
After much googling, it turns out the culprit is disabled ipv6 on server B.
As a workaround, the following line needs to be added to /etc/ssh/sshd_config:
AddressFamily inet
Should now work after `sudo service ssh reload`.
I found the solution here and here.
Problem
I connect to two different SSH servers A and B using PuTTY+Xming from Windows. On server A, `echo $DISPLAY` yields localhost:10.0 (already set somehow); while on server B, I've manually set the `DISPLAY` variable to be localhost:10.0 as well. However, I am able to use `xclock` on server A, but not on server B. The only way I could get it to work on server B is by adding server B's IP address to Xming's `X0.hosts` configuration AND setting the `DISPLAY` environment variable to my Windows machine's IP address. My question is, how come server A's `xclock` works with minimal setup (just enable X11 forwarding and set display location to localhost:0.0 in PuTTY), but not server B's? In addition, how can one look for the script that set the `DISPLAY` environment variable to localhost:10.0 on server A? Additional info: 1) Server A has an ~/.Xauthority file that gets automatically created upon login, while server B does not. 2) Server B's /var/log/auth.log contained the following error: sshd[1404]: error: Failed to allocate internet-domain X11 display socket. 3) I changed the hostname of Server B once before.