Older Macs (again)

James Keating jkeating at ksd140.org
Wed Dec 20 16:44:49 UTC 2006

Simon Hobson wrote:
> <>James Keating wrote:

> <>The machines, mainly PCs, on the network acquire leases 
> and IPs
> without a problem. Most of the machines on the network, mainly
> Macs running OS X and OS9.x, do the same.
> However, some Macs running OS9.x on the network don't acquire
> a lease and don't receive an IP. Prior to switching to the MacMini with
> dhcpd,
> there was an NT server running DHCP server on that network, and there were
> always a lot of BAD_ADDRESS entries. The event viewer showed a lot of NAKs
>>from Macs requesting IPs such as and the like. This led me to
>>that certain Macs running OS9.x and earlier were not properly requesting
>It's a Mac thing, they release their address when they shut down, and 
>when they start up they request something like that from the dhcp 
>server - I don't know if it's some sort of attempt at self 
>configuration. Normally the DCHP server will just NAK it and the 
>client will then start off on a discover cycle.
Is there a version of OT that doesn't do that Mac thing? I didn't know 
the Macs released their addrs on

>>On the MacMini, here's what /var/log/asl.log says. I don't know if
>>[Time 2006.11.30 13:42:09 UTC] [Facility daemon] [Sender dhcpd] [PID -1]
>>[Message Abandoning IP address declined.] [Level 3] [UID
>>-2] [GID -2] [Host earths-computer]
>>Has anyone else seen this?
>How long ago did you switch servers ? How did you do it ?
We switched near the end of November. On PCs we did ipconfig/release and 
renew. On
the Mac OS Xs we did nothing - it just worked. But on the Mac OS9.x's  
we threw out
the TCP/IP prefs, rebooted, and started fresh.

>If you just turned off one server and turned on another then you 
>would expect that. The new server has no record of what addresses are 
>already leased out, so when a client comes along asking for a new 
>lease, the server will pick an address, and there's a good chance 
>that there's a client using it - so it gets abandoned.
No, we didn't do that. I think the NT box crashed and burned on a 
Friday, and Monday
or Tuesday we put that net on the MacMini.

>Some devices will have a firewall enabled that blocks pings (yuck), 
>in which case the dhcp server will not see it (so can't abandon the 
>address), but the client will do an arp request and find it before 
>accepting the address - in which case the client will decline the 
No, no client-based firewalls in use. And just Cisco routers connecting 
the two LANs, with the router having an ip helper-address set to the MacMini.

>Eventually things will settle down, and once all old leases have 
>expired the messages will stop. What you should do then is to stop 
>the dhcp server, and delete the abandoned leases from the leases 
>file. They are never deleted, and they are only recovered for use as 
>a last resort - the result can be a significant increase in address 
>churn on the network it the result is few free leases (or even no 
>free leases).

>Also, do you have any devices with fixed addresses in the dynamic 
>ranges - this can also give this sort of message.

>Finally, it suggested that you avoid the .0 and .255 addresses. 
>Whilst it's perfectly legal, there are some client implementations 
>out there which are "not quite 100%" and don't work properly with 
>them. So some people prefer to put :
>     range;
>     range;
Yes, I knew that. Just lazy.

Thank you.

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