Bug#886635: arpwatch: tries to start before network is up

[Roland Rosenfeld]

Package: arpwatch
Version: 2.1a15-5
Severity: normal

Dear Maintainer,

I use arpwatch via systemd, but had to notice, that arpwatch tries to
start up before the network interface is fully up (some spanning tree
issue).  This leads to arpwatch failing and not correctly starting up.

Jan  8 10:13:15 sys-241 systemd[1]: Starting arpwatch service on interface eth0...
Jan  8 10:13:15 sys-241 arpwatch: Could not get IPv4 address on eth0 for bogon detection
Jan  8 10:13:15 sys-241 arpwatch: No subnets to watch configured; either use -a to process bogons or watch subnets explicitly using -n network/mask
Jan  8 10:13:15 sys-241 systemd[1]: arpwatch at eth0.service: Control process exited, code=exited status=1
Jan  8 10:13:15 sys-241 systemd[1]: Failed to start arpwatch service on interface eth0.
Jan  8 10:13:15 sys-241 systemd[1]: arpwatch at eth0.service: Unit entered failed state.
Jan  8 10:13:15 sys-241 systemd[1]: arpwatch at eth0.service: Failed with result 'exit-code'.
Jan  8 10:13:16 sys-241 systemd[1]: arpwatch at eth0.service: Service hold-off time over, scheduling restart.
Jan  8 10:13:16 sys-241 systemd[1]: Stopped arpwatch service on interface eth0.
Jan  8 10:13:16 sys-241 systemd[1]: Starting arpwatch service on interface eth0...
Jan  8 10:13:16 sys-241 arpwatch: Could not get IPv4 address on eth0 for bogon detection

I think that arpwatch should wait until the interface is up, so I
created the following
/etc/systemd/system/arpwatch at eth0.service.d/override.conf which fixes
the issue for me:

[Unit]
After=network-online.target

[Install]
Wants=network-online.target

Maybe it would be a good idea to add something like this to
/lib/systemd/system/arpwatch at .service

Greetings
Roland