Re: [TCLUG:21970] Should DSL or Cable modem

[Adam Maloney <adamm@sihope.com>]

Well if his dhcp client sends a Renew request to the server, the server
can reject it.  The dhcp client will then just ask for a new IP.  As long
as he doesn't muck with the client (or bypass it altogether and just
statically configure it) he can't cause any trouble.  The server can
always reject renew requests if the address has already bgeen reassigned.
I don't think there's anything he can do to the configuration of the
client that could screw anything up, I think he'd have to modify the
source.

If the IP has already been leased to someone else, and his client asks for
that IP (in a renew request) the server will send a NACK back, then an
OFFER with a new IP.

In any case, by changing the lease time you're probably not helping
yourself at all.  As soon as the lease ends your client will send a renew
request back to the server and you'll get your IP back anyways.  The lease
time just dictates how long before you have to renew again, but if the
server reboots you may be SOL.  I believe ISC's stores the lease
information in /var somewhere so if the server restarts it'll know who has
what leased...but I don't know about whatever DHCP server they're using.
If it's Microsoft's it'll probably explode or something...

Adam Maloney
Systems Administrator
Sihope Communications

On Tue, 3 Oct 2000, Thomas T. Veldhouse wrote:

> Yeah, and that somebody is going to be pissed if they find out that somebdoy
> is using their IP and causing them to have problems with there cable modem.
> Most users are not going to know what the problem is and they are simply
> going to call MediaOne and complain.  If MediaOne then finds this, one had
> better watch out, because suddenly the support costs are larger than the
> profits that they are making off of the trouble causing individual.
> 
> Tom Veldhouse
> veldy@veldy.net
> 
> ----- Original Message -----
> From: "Adam Maloney" <adamm@sihope.com>
> To: <tclug-list@mn-linux.org>
> Sent: Tuesday, October 03, 2000 9:17 AM
> Subject: Re: [TCLUG:21970] Should DSL or Cable modem
> 
> 
> > Well if they ran ISC's DHCPd they can set Max-Lease-Time, which is the
> > maximum amount of time a given address will be leased for.  That's not to
> > say that when the lease expires you won't renew and get it again, but if
> > you don't renew right away someone else will probably get it.
> >
> > Adam Maloney
> > Systems Administrator
> > Sihope Communications
> >
> > On Mon, 2 Oct 2000, Eric F Crist wrote:
> >
> > > Trust me, it works.  I've gotten calls from TW and MediaDumb (aka ATT)
> and
> > > they've not been able to stop it, short of pulling the provision for
> your MAC
> > > address.
> > >
> > > But, there are ways around that too.  =P
> > >
> > > On Mon, 02 Oct 2000, you wrote:
> > > >
> > > > Thats *only* if the other end accepts such bad things.
> > > >
> > > > AFAIK, you can setup ISC to ignore it.
> > > >
> > > > * Eric F Crist <ecrist@ardent-hacker.net> [001002 21:37]:
> > > > > After a little more research (I had a brain-fart) the file, on a
> freebsd =
> > > > system
> > > > > is /var/db/dhclient.leases
> > > > >=20
> > > > > This file is realatively simple and straightfoward.  For information
> on y=
> > > > our
> > > > > box, type man dhclient.leases
> > > > >=20
> > > > > If you have questions or comments, feel free to email me.
> > > > >=20
> > > > >=20
> > > > >=20
> > > > > Au Contrair on the static IP.  If you're into the computer hacking
> side of
> > > > > things, you can simply change your lease on the IP to never expire.
> Ther=
> > > > e's a
> > > > > file located on your hard drive that actually sets your lease.  This
> is
> > > > > overwritten at the time of renewal by the DHCP server.  I have done
> this =
> > > > myself
> > > > > and know others who do it successfully.  Maybe not a legit static
> IP, but=
> > > >  until
> > > > > they find out, who cares?=20
> > > > >=20
> > > > > On Mon, 02 Oct 2000, you wrote:
> > > > > > Disadvantages to cable modem (from my point of view)
> > > > > > - no static IPs, may be coming soon though
> > > > > > - no services on your machine, or you get booted
> > > > > >=20
> > > > > > Advantages to cable modem
> > > > > > - much faster
> > > > > >=20
> > > > > > I got this information from the Time Warner sales rep and the tech
> rep =
> > > > that
> > > > > > showed up at my apartment complex trying to get subscribers.
> > > > > >=20
> > > > > > --=20
> > > > > > Jon Schewe | http://eggplant.mtu.net/~jpschewe
> > > > > > For I am convinced that neither death nor life, neither angels=20
> > > > > > nor demons, neither the present nor the future, nor any=20
> > > > > > powers, neither height nor depth, nor anything else in all=20
> > > > > > creation, will be able to separate us from the love of God that=20
> > > > > > is in Christ Jesus our Lord. - Romans 8:38-39
> > > > > >=20
> > > > > >=20
> > > > >
> > ---------------------------------------------------------------------
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> > > > > --=20
> > > > > Eric F Crist
> > > > > System Administrator
> > > > > Ardent-Hacker.net
> > > > >=20
> > > >
> > ---------------------------------------------------------------------
> > > > > To unsubscribe, e-mail: tclug-list-unsubscribe@mn-linux.org
> > > > > For additional commands, e-mail: tclug-list-help@mn-linux.org
> > > > >=20
> > > >
> > > > --=20
> > > > Scott Dier <dieman@ringworld.org> #nicnac@efnet=20
> > > > http://www.ringworld.org/  finger:dieman@destiny.ringworld.org
> > > >
> > >
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> > > --
> > > Eric F Crist
> > > System Administrator
> > > Ardent-Hacker.net
> > >
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