Client restarts when logged in

[d78ui98]

This is a known issue. It is caused because of race condition in this code -

for i in $(seq 1 9); do
(
    nbd-client server -N /opt/ltsp/i386 /dev/nbd$i
    nbd-client -d /dev/nbd$i
) &
done

reference - https://github.com/NetworkBlockDevice/nbd/issues/59 Since ltsp now uses nbd sometimes it affects the ltsp setup. There is no error message to tell what is happening so I did tail -f /var/log/syslog on the server. And this was the output when I boot from the client

Jul  1 20:34:57 ubuntu-bionic nbd_server[1273]: Spawned a child process
Jul  1 20:34:57 ubuntu-bionic nbd_server[2335]: virtstyle ipliteral
Jul  1 20:34:57 ubuntu-bionic nbd_server[2335]: connect from 192.168.111.108, assigned file is /opt/ltsp/images/amd64.img
Jul  1 20:34:57 ubuntu-bionic nbd_server[2335]: Can't open authorization file /etc/ltsp/nbd-server.allow (No such file or directory).
Jul  1 20:34:57 ubuntu-bionic nbd_server[2335]: Size of exported file/device is 485146624
Jul  1 20:34:57 ubuntu-bionic nbd_server[2335]: Starting to serve

The client after login just restarts and brings back the login screen. I know how to fix this one.