L2TP disconnects after timeout on Alpine Linux 3.8

[jayavanth]

After about 10-20 mins of idle time, xl2tp disconnects and therefore VPN disconnects. I saw right after it disconnected that the file /var/run/xl2tpd/l2tp-control was empty

When I populated the file with echo "c myvpn" > /var/run/xl2tpd/l2tp-control, the VPN connected again.

Who is writing into that file? Why is that file empty after some idle time?

[dkosovic]

Although located on the file system, it isn't really a file, but a named pipe :

$ ls -l /var/run/xl2tpd/l2tp-control
prw------- 1 root root 0 Oct 31 08:59 /var/run/xl2tpd/l2tp-control

$ file /var/run/xl2tpd/l2tp-control
/var/run/xl2tpd/l2tp-control: fifo (named pipe)

With that named pipe which xl2tpd uses for accepting commands, nothing is written to the file system, but to kernel memory.

where are you seeing that /var/run/xl2tpd/l2tp-control is empty?

/usr/sbin/xl2tpd-control was introduced to send control commands to xl2tpd via the named pipe. You are using the older approach of redirecting stdout to the named pipe.

I suspect the issues is not with /var/run/xl2tpd/l2tp-control, but something else.