Dynamically adding entry in a table

[Tom Uffner]

quentin.narvor wrote:
> I'd like to dump (dup-to operation) all traffic from a subset of hosts
> belonging to my internal network. This subset of hosts will be stored in
> a table.
>
> I have another table referring to blacklisted hosts (ie botnets, etc).
> When a
> packet goes through the firewall with destination host = an IP of
> blacklist table, I'd like to trigger an addition to the first table (the
> one containing internal host to dump traffic).

let's call your two tables watchhosts & blackhosts.

ensure that you are logging packets w/ destinations in the blacklist table
(eg. "pass out log on $ext_if to <blackhosts>"). if you are logging a lot
of traffic you may find it useful to create a separate pflog for this rule
and use "log (to <interface>)" in this rule.

write a script that reads the pflog and parses source addresses from packets
that trip the blackhosts rule above. the script then uses something like
"pfctl -t watchhosts -T add <src addr>" to add the address to your table.

please consult the man pages pf.conf(5), pfctl(8) and pflog(4) for additional
information.