DHCP/DDNS Troubleshooting
 

I'm having difficulty troubleshooting some DHCP/DDNS interactions on a LAN...

A Win98 SE system boots, requests an IP, and the DHCP server grants a lease. Immediately thereafter the DHCP server sends an update to the DNS, and an 'A' record is created for the recently granted IP. So far, so good.

An OS/2 v4 system boots, requests an IP, and the DHCP server grants a lease. However this time no update is sent to the DNS from the DHCP server.

Any suggestions as to where to start looking?

-d.

Aside from /var/log/syslog, and unfortunately dhcpd doesn't have an option to crank up the verbosity of logging, but that's where the request and lease hand-off information is going to be. Its probably a matter of "how" the client asks for a lease. For instance, the windows default may be that it asks for a hostname and so dhcpd creates a dns record for it, but the OS/2 machine doesn't handle it like that.

Cheers,

Finegan

I think you've hit the nail on the head... I didn't roll far enough back through the syslog this morning to find the lease requests for each client, but a quick glance at dhdpd.leases shows no hostname for the OS/2 system (the first entry below).

lease 192.168.42.30 {
starts 4 2002/06/06 07:03:38;
ends 4 2002/06/06 19:03:38;
binding state active;
next binding state free;
hardware ethernet 00:60:67:24:0c:a8;
uid "\001\000`g$\014\250";
}
lease 192.168.42.31 {
starts 4 2002/06/06 10:29:52;
ends 4 2002/06/06 22:29:52;
binding state active;
next binding state free;
hardware ethernet 00:40:f4:42:38:df;
uid "\001\000@\364B8\337";
set ddns-rev-name = "31.42.168.192.in-addr.arpa.";
set ddns-txt = "31923ef723277ca84d26a475c2e7d3b173";
set ddns-fwd-name = "Stormie.miliways";
client-hostname "Stormie";
}

I still have to check the syslog to verify the actual behavior, but I have a suspicion that the OS/2 system may not include its hosname in the DHCP request...

Assuming that that is the case, IIRC one can force a hostname upon a dhcp client via the use-host-decl-names keyword?

I just read up on the man page for dhcpd.conf as I've never had to plunger force feed a machine a hostname either, but yeah that seems to be the way to do it, especially if your handing out fixed IPs based on card MAC addresses.

Post back on how it works.

Cheers,

Finegan

No luck there I'm afraid...

While use-host-decl-names can indeed be used to force a hostname upon a client, doing so does not trigger a DDNS update.

I haven't been able to find any documentation on it, but I suspect that dhcp 3 requires that the client system identify itself with a hostname in order to trigger the DDNS update.

The OS/2 system *does* have a DDNS client, however it appears to use a protocol proprietary to IBM and/or OS/2. Attempts to have the OS/2 system's DDNS client send an update return an error stating "the DDNS server did not understand the request."

There is however a tool on the OS/2 system called "nsupdate," which appears to be a command line tool for manually updating resource records. I have no idea if bind will accept requests made by nsupdate; I haven't had the opportunity to test it yet.

I'm going to try two routes... It *may* be possible to configure the DDNS client program to send updates in a format which bind will accept. If not, I'm going to have a go at writing a script on the OS/2 system which will use nsupdate to do the work.

This is proving to be an interesting exercise... ;)

The other route, slightly uglier, is to see if any of the modern dhcp client daemons will compile and run against an OS/2 machine, but really I don't know dink about that OS, so maybe I'm blowing smoke.

Either way, luck,

Finegan