[aclug-L] Re: Denied connections

[Chris Owen <owenc@xxxxxxxxxxxx>]

On Sun, 26 Aug 2001, Bruce Bales wrote:

> I've had the same IP address since July 26 and I turned the modem off
> for a week while we went to Colorado week before last.

While there are probably hundreds of different ways of doing DHCP, most
implementations I've seen will usually give the same IP address back to a
MAC address if that address is available when your computer requests the
new IP address.

So if you have one IP address and your lease expires and you request a
"new" one with most DHCP servers you will get back the same IP address as
long as it is available.  Now that chances of that happening depend on a
lot of factors, but when you have a finite number of clients on a server
and they tend to all get their "own" IP address every time, the chances of
"yours" being available are pretty good.  In such a model it wouldn't
matter much when you rebooted your machine, but rather things would only
change when the DCHP server was rebooted (asumming it didn't cache this
type of data between reboots).

One would think that Cox would not necessarily want this type of behavior
(which results in people having nearly static IP addresses), and would
modify their DHCP client accordingly, but then again they are a cable
company ;-]

Chris

> Ironrose wrote:
>
> > I have been told that that is true.  There are more users than they have
> > IP addresses, that is why they use dynamic IP's, rather than static
> > IP's.  They scan to see if someone is using the modem, and if they are
> > not, the IP address is given to someone else.  This allows more people
> > to use the KS cable with less expense.  This doesn't happen very often
> > any more since KS cable bought more IP addresses.  This is the story I
> > was given in my NT and Internet classes @ Butler.  :-}
> >
> > David Carmichael wrote:
> > >
> > > I do not know if the local RoadRunner Service does this.... But I heard on
> > > "The Screen Savers" (TechTV) that some cable modem systems will ping
> > > connected modems to know if they need to keep the reserved IP address open
> > > or if they can reassign it to some other users system.
> > >
> > > ----- Original Message -----
> > > From: "Bruce Bales" <bbales@xxxxxxxxxxx>
> > > To: <discussion@xxxxxxxxx>
> > > Sent: Sunday, August 26, 2001 7:29 PM
> > > Subject: [aclug-L] Re: Denied connections
> > >
> > > >
> > > > Yes, most of mine are ports 80 and 139, with an occasional 27374.
> > > >
> > > > Thanks for the explanation, James.  Makes sense and now I feel more
> > > secure.  Also,
> > > > telnet is turned off by the stock Frazierwall.
> > > > bruce
> > > >
> > > > james l wrote:
> > > >
> > > > > Root/Great Overall Dictator replies:
> > > > > > I've been leaving my Frazierwall firewall turned on 24/7 for several
> > > days.  It
> > > > > > has been denying about 200 hits each 24 hours.  In the 24 hours
> > > between about
> > > > > > 0600 yesterday and 0600 today, I got almost 650 hits denied.  Kinda
> > > makes me
> > > > > > wonder what was going on before I got the wall up.
> > > > > >
> > > > >
> > > > > Lots of the same here, mostly on port 80(http) (code red anyone?)
> > > > > and a few on port 139 (smb).
> > > > >
> > > > > > A related question; What keeps someone from breaking in on one of 
> > > > > > the
> > > ports that
> > > > > > is not denied by the firewall?
> > > > > > bruce
> > > > > >
> > > > >
> > > > > Essentially each connection opens a 'tunnel' to the outside and if the
> > > packet
> > > > > is not sent as a response over one of these tunnels, it denys the
> > > packet.
> > > > > Unless, you specifically allow access to say port 80 (forewared to
> > > another
> > > > > machine), then there might be some problems.
> > > > >
> > > > > James L.
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> > > >
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> > > >
> > > >
> > >
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