Re: [gentoo-user] [Not specifically Gentoo] Forcing a new IP address with DHCP

[John J. Foster]

On Fri, Dec 02, 2005 at 05:07:22PM -0800, Ryan Tandy wrote:
> >I have a Linksys WRT54GS router running openWRT firmware that gets its
> >IP via DHCP from my ISP. That's all working fine. I also have an account
> >with dyndns.org that is supposed to get updated when my IP changes. This
> >is where I've screwed something up because it's wasn't. I think I have
> >it configured properly now, but won't know until my IP changes again.
>
> In the configuration on the dyndns website, enter an IP for your entry
> that you know is wrong.  Wait the interval you configured and see if it
> updates to the correct one.  Also, there should be an option somewhere
> to force your dyndns client to update immediately, but I'd recommend
> waiting the interval just to make sure that works too.  Maybe turn it
> down to 5 minutes or something to reduce the wait. ;)

I've done this, and also had to change the IP in /tmp/ez-ipup, which
holds the routers config for the last time IP was changed. After doing
these changes, 

ipdown wan
ipup wan

recognized that the IP was different, and updated appropriately. Right
now I have the following command being run hourly from crontab

/usr/sbin/ez-ipupdate -c /etc/ez-ipupdate.conf &

and that doesn't work if wan hasn't been taken down and back up again,
because the ez-ipdupdate script just compares the values in /tmp/ez-ipup
file with dyndns, and doesn't account for the actual value shown with
ifconfig vlan1.

But what doesn't happen, and I think _should_, probably via udhcpc, is
that if my satellite modem goes down or changes IP, the router should 
recognize this fact and automagically reconfigure wan via ipdown and
ipup.

I'm really confused here.

Thanks,
John