[NCLUG] Cable Modem Refugees

[Chris Wolney]

> > Michael Dwyer wrote:
> The funny thing is, as long as the gateway and netmasks don't change,
> there's not much they can do to keep you from sitting on an IP.  Most
> well-behaved DHCP servers will ping an address to see if someone is
> there before giving that address away to someone else.

True enough.  If I remember the RFC (2131?) has your client ask for a
renewal after half of the lease has expired.  If it was unsuccessful, it
should check again at 7/8 of the lease interval.  I had to do some
troubleshooting on this with Microsoft laptop clients (ie. not always on the
net when travelling), and I remember that Microsoft's DNS servers didn't
follow the RFC completely.  These renewal time values could be set on the
server, but I haven't messed around with the linux dhcpclient to see if it
can be overridden.

I am running one of those Linksys Cable/DSL routers that is on 24/7, so if
they use an RFC-compliant DHCP server, I would think my IP will stick around
for awhile.  If you leave your machine on 24/7, or at least a bit over 50%
of the lease interval, that could solve the problem-- we will see if attbi
does anything funky with DHCP requests and renewals.  You could also script
a dhcp renewal request...

-Chris