I recently switched from CentOS7 to Ubuntu 18.04. I used to be able to pkill -u user and it would kill all my processes. However, when I try to do the same in Ubuntu, my SSH session remains active. Using XRDP, I have a similar issue. If I try using "pkill -u user", my XRDP session is terminated and, as root I can see the following process:
user 20848 1 0 09:33 ? 00:00:00 /usr/bin/ssh-agent -s
However, once that process is there, I cannot log back in via XRDP, and I get a few errors upon login. My only fix is to pkill -u user as root. Once I do that, I am able to use XRDP again.
Regardless, I cannot see that process as "user" using ps but I can kill it if I know the process PID.