i have a linux client which uses pppoe to connect to the internet and
everytime this client comes online I wanna bind his ipadress to a subdomain.
dyndns is not an option due to their TTL.
It looks like i have to setup my own nameserver on my root server to accomplish this task because I cannot create the keys needed to run an nsupdate on the client with a provider nameserver... am I correct?
If so is there a good Howto for setting up a bind server for this specific task?
Well dont you just need to create an A-Record for this IP on your DNS Server?
If your domain is 'google.com' and you wanted your host to be called 'server1'. Create an A-Record for 'server1' and point it to your machines IP.
Unless I am misunderstanding what you are asking for help with.
I havent ever maintained pppoe but if it uses dhcp to provide the ip address to the client, you could do updates from the dhcp to the dns.
Instructions on how to do this for debian here: http://www.debian-administration.org/article/Configuring_Dynamic_DNS__DHCP_on_Debian_Stable
Do not thou that you can adapt these to other distros too. You can find the same software atleast on fedora and ubuntu, difference is only how you install the required software.
One posibility is to set their machine to register with somebody like DynDNS. They have all the software you need to automatically notify them when they come online/go offline. This will give them a domain name of something like whatever.homelinux.org (it does not really matter). You then put static CNAME entries in your DNS to point your nice domain names eg southern.company.com to point to whatever.homelinux.org.
When they come online the domain will start to resolve and stop when they go off line since DynDNS have low TTL for this very reason. You can use large TTL in your zone file since the CNAMEs will not change.