Re: Follow arp table for captive portal

Gian Piero Carrubba <[email protected]> Fri, 17 May 2013 08:46:11 +0200
Newsgroups gmane.linux.debian.devel.firewall
Message-ID <[email protected]>
* [Thu, May 16, 2013 at 04:28:04PM -0700] Ryan Hiebert:
>I also thought of a 3, but I'm not sure if its reasonable or possible:
>3. Get iptables or similar to log unknown mac/ip pairs that it sees.

Maybe you can use arptables for this. But I would go for the easiest 
path: just log any NEW (allowed) forwarded connection.

-A FORWARD -i ${if_in} -m state --state NEW -j LOG

(or -m conntrack --ctstate NEW ) then postprocess the logs when needed 
or use -j ULOG|NFLOG for fancy things.
This way you have the (MAC) originator for every "established" 
connection.

Ciao,
Gian Piero.