Create `tallow` and `tallow6` ipsets, hook up to iptables
and create a single rule in the INPUT chain of the filter
table.
The ipsets created have `expire` timeouts set by default
which removes the need to do pruning, so we can erase entries
immediately from our LL when blocking.
This is a far more robust way of tailing the journal that seems
to work on 2 different journal versions. It's a bit more involved
and journal slowness may cause it to take several seconds to iterate
through the journal after a rotate or after startup, but it's far
more reliable than the old method.
I've also pushed all the output to stderr which makes the blocked/
unblocked messages end up in the journal itself.
Adds a signal handler to gracefully shut down in case of exit
signal, while doubling as a way to quickly dump the current
state table.
A journal tailing error workaround thanks to ssh-blocker.
Auke Kok