Subject: Re: Needing help with preventing IP theft
To: Bill Studenmund <>
From: Dan Debertin <>
List: tech-net
Date: 08/11/2000 14:01:08
Easy answer:  find an ISP who supports PPP-over-ATM, or ask your current
ISP if they support it. ISPs are switching from bridged DSL for the reason
that you describe below. PPPoATM is authenticated, has access control, and
doesn't saturate the bridge with unnecesary broadcast traffic.

If that isn't an option, then I would suggest a cronjob that checks for
the conditions that you describe, and runs the necessary ifconfig
commands. This would be treating the symptoms, not the problem,
however. The real answer would be to get on the phone with your ISP's
admins, and try to figure out who is causing the problem.

RFC1483 bridging is _not_ optimal DSL service. You should find an ISP that
supports PPPoATM if at all possible.

~Dan D.
-- I feel the earth move.
-- I feel the tumbling down, the tumbling down.

++ Dan Debertin
++ Senior Systems Administrator
++ Bitstream Underground, LLC
++ (612)321-9290

On Fri, 11 Aug 2000, Bill Studenmund wrote:

> Someone has taken to stealing my DSL IP address. I'm not sure if it's
> malicious or someone just misconfigured the computer, but I need it to
> stop.
> My setup is bridged ethernet DSL. So someone else in my little /26 net
> ifconfigs an interface and the arp announce overwrites the arp entry for
> me.
> I've found that ifconfig iface delete; ifconfig iface addr netmask
> gets me back my IP, but it breaks all of the existing
> connections I have. I'd rather find another way to generate the arp
> announce. :-)
> I asked on icb about programs to help, and Charles mentioned arpwatch with
> the caveat that it only watches. Well that's half the battle. :-)
> Does someone know of a program which will generate an arp announcement
> when run? That's all I need to fight back..
> Take care,
> Bill