[TriLUG] DDNS (and maybe DHCP) on host not router

[Randy Barlow]

Tom Roche wrote:
> Right, but in the PN above, it *is* the router that's getting the IP#,
> so it's the router which needs its DNS record updated when its IP#
> changes, so it's the router that needs the dyndns update client ...
> no? (At least, that's how I understand RR's Surfboards to work--they
> give 1 IP# to 1 attached device, and if you change the device you've
> gotta powercycle the modem.) And won't that be the case whenever the
> router is firewalling?

You are correct that it is the router that gets the IP, but it doesn't
have to be the router to run the update client (though it can be).  It
is possible for devices on the private network to determine the public
IP of that router.  Actually, you can see that for yourself - go to
http://whatismyipaddress.com and you will see your public IP, even if
you are on a machine on the PN.  I think the DynDNS update script works
similarly.

-- 
Randy Barlow
http://electronsweatshop.com