[NCLUG] ipchains and firewalls

[rosing at peakfive.com]

Hi,

I have 2 questions about ipchains and firewalls.  The first is I
executed 

  ipchains -R input 8 -j ACCEPT -p tcp -s 130.20.118.155 x11:6009

along with

  xhost +

and I can now have X apps display on my machine from 130.20.118.155.
Is this all I did? Or did I open up something else by accident?  (I'm
an ipchains newbie) Where is "x11" defined? I assume it's just a "well
known" port (something like 6000?).

Second question:  If I buy one of the cheap hub/router/firewall boxes (as
opposed to using an old machine as a firewall and buying a hub) can I
have the same kind of control as what I'm doing with ipchains?  A
specialized box would be more convenient for several reasons but I
would like to have the kind of control that ipchains seems to provide.

Thanks,

Matt