[Sussex] My adsl modem/router

[john]

Hi list,

Last week, I picked up this marvellous piece of kit from Neil Ford called a
Solwise SAR110.

It fulfills all my expectations, and more. The only minor snag, is that it
appears that the 110 is just a bit too clever for a dummy like me.

The configuration went like a breeze. So, thinks me, I'll go to grc's site
and check it out with "Shields Up".

Whilst the Shields up test, says it can't get in, the "probe my ports" test
tells me that ports 21,23 and 80 are open. This is presumably because that
is the default for the modem/router.

Now according to this
http://www.adslguide.org.uk/hardware/reviews/2003/q1/sar_110.asp I
understand that this shouldn't be a problem because amongst others, the
SAR110 supports  "NAPT rule: The default rule that is used in a basic single
IP setup. This blocks unsolicited incoming data, but allows replies to data
you requested to return".

So can somebody explain why I might need to further configure the built in
firewall and/or IP filters to do something about these open ports? i.e. are
they anything to be concerned about?

Or does anyone know the how/why of whether I can stop both my mandrake
install and wind0w$ XP from broadcasting my external IP - that is presuming
that to do so would mean that when I'm not using my connection, it is
"stealthed"?

regards

John D. (flag officer in stupid questions)