Previously on my dial-up connection I configured iptables (via guarddog)
to 'stealth' all ports. Now I have an ADSL connection, and regardless of
what changes I make to iptables, all ports are now visible (but closed).

I get the same problem in Win XP running ZoneAlarm, so I'm guessing the
problem is with the modem/router, not the PC.

Is it possible to configure the modem/router to stealth the ports? (I'm
using a Netcomm 1300+4 modem)

TIA