[Nottingham] port problem

[Graeme Fowler]

On Sat, 2004-06-26 at 18:08, dalkus wrote:
> I use a hardware router and i opened the ports 50000-50004 and forwarded it to 
> my box. But this didn't fix the problem, i did a check and i got this:

Umm... I might be being dumb here, but if you opened ports 50000-50004
and then nmapped 30000-30004 you'd find a slight misalignment.

> [root at localhost]# nmap -P0 -sS -p 30000-30004 localhost

OK, so you see all the ports as "closed" - this is the correct
behaviour, since they're only opened up to a remote client once a DCC
session is in progress (again, I could be wrong) - AFAIK DCC sessions
only get opened when you start them up:

you offer a DCC transfer to someone
they initiate a connection back to $port
your IRC client is expecting that, so opens the port up and gets on with
it.

> So the next logical step was to tell iptables to open those ports on this box 
> but i found it wasnt installed...

iptables doesn't "open" ports. Sure, it can reject or drop packets
destined for them, but if no application has a listening process parked
on a port then no amount of iptables shenanigans will make any
difference.

I googled too. The thread including
http://mail.nl.linux.org/xchat-discuss/2002-06/msg00103.html seems like
it might help you out.

Graeme