Logging your internet connection state in OpenBSD with ifstated

Sometimes your internet connection goes down…

… and when it does, you might not know about it, such as if you are out. It can be handy to collect dates and times for when this happens. This is especially true if you have a SLA (service level agreement) with your ISP and are able to get compensation.

Initially, I set about writing a script to search through ifconfig(8), when I stumbled upon ifstated(4). This is a daemon that ships since OpenBSD 3.8 which does “stuff” when interfaces change.

Specifically, you can set up a complete state machine and configure the transition criteria. It even has init points so temporary transition states are not required!

This is possibly one of the simplest use cases imaginable, one can configure it for more complex for situations involving multi-homed connections, DMZs, and carp(4) virtual interfaces that might be part of multiple redundant connections.

Here, I have logging working. I also thought it would be useful to use the built in piezo transducer to buzz, but alas, /dev/speaker does not work on sparc64 architecture. It may work on Raspberry Pi, and should work on i386 and amd64 architectures.

Backup /etc/ifstated.conf and paste this in there:

# monitor pppoe0 and log on changes
# inspired by http://openbsd-archive.7691.n7.nabble.com/ifstated-recipe-for-down-gt-up-td71811.html

# state transitions:
# auto        ---- detect down --> pppoe0-down
# auto        ---- detect up ----> pppoe0-up 
# pppoe0-up   ---- detect down --> pppoe0-down
# pppoe0-down ---- detect up ----> pppoe0-up

init-state auto

pppoe0_up="pppoe0.link.up"
pppoe0_down="pppoe0.link.down"

state auto {
    run "logger -t ifstated pppoe0: AUTO!"
    if ($pppoe0_up) set-state pppoe0-up
    if ($pppoe0_down) set-state pppoe0-down
}

state pppoe0-up {
    init {
        # TODO: play a beep. consider something like
        run "echo 'AAA' > /dev/speaker"    # does not work on sparc64
        run "logger -t ifstated pppoe0: UP!"
    }

    if ($pppoe0_down) set-state pppoe0-down
}


state pppoe0-down {
    init {
        # TODO: play a beep. consider something like
        run "echo 'AAA' > /dev/speaker"    # does not work on sparc64
        run "logger -t ifstated pppoe0: DOWN!"
    }

    if ($pppoe0_up) set-state pppoe0-up
}

Configure and tweak as appropriate, and test it out using ifstated -d or ifstated -dv / ifstated -dvv with increased verbosity. -d sends output to STDOUT, and -v adds more and more verbose output.

Once happy, start the daemon for realzies with rcctl start ifstated and to enable it at boot rcctl enable ifstated.