Working with a Cisco router
dhcp1 at thehobsons.co.uk
Fri Feb 5 19:31:38 UTC 2010
Tim Gavin wrote:
>I have just identified a problem where a small group of people are
>'stealing' their IPs. It appears that they're grabbing their DHCP
>assigned address and setting it in their router as a static. This has
>the obvious consequences.
>What I'm wondering is if anyone knows of a script or app that will
>work with ISC DHCP that can set a static ARP in my Cisco router based
>on the DHCP lease. Maybe using SNMP or something. . . I know it's a
>strange request, but am hoping someone has dealt with this before.
If your leases are long enough, then you could periodically scan the
leases file to get a list of IP-MAC pairs and script an update to a
switch or router. Or possibly more useful, compare this with the
router ARP table and build a blacklist of devices to redirect into a
Actually, this could be a reasonably safe way to do it - you could
include logic that would include expired leases less than a certain
age which would avoid false blockings just after a lease expires.
However, a lease would disappear if the address got reallocated to
another customer, but in that case, the faster you deal with the
offender the better.
WANTED: "Software CD ROM Kit" for Canon CLBP 360-PS printer (Canon
part no RH6-3612, or possibly RH6-3810, or RH6-3610 might do). I've a
dead HD and need this CD so I can replace the disk and re-install the
printer OS on it. If anyone knows where I might get hold of one I'd
be grateful - requests to Canon drew a blank, it's been out of
support for years.
Alternatively, if anyone has one of these and would let me image
their hard disk ...
Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.
More information about the dhcp-users