Macbook Pro/MacOS X 10.6.8 won't accept DHCPOFFER

[jeffrey j donovan]

On Mar 16, 2012, at 12:10 PM, Chuck Anderson wrote:

> Has anyone experienced a problem where MacOS X 10.6.8 (or other
> versions) won't accept the DHCPOFFER from the server?  I'm pretty sure
> this isn't affecting ALL Macs on my network, because if it was I would
> have many more complaints than just the one system I'm troubleshooting
> now.  But this one Mac won't accept DHCPOFFER from either its wired
> Ethernet (en0) or wireless Airport (en1) interfaces.  I've tried
> everything short of deleting plist files or reinstalling the OS, but
> nothing has worked so far.  The firewall is disabled, no Internet
> Sharing option is enabled (but it had been), the network configuration
> has been deleted and re-created, "Locations" were deleted, all
> Software Updates are applied, etc.
> 
> I've confirmed that the DHCPOFFERs are getting to the Mac by doing
> tcpdump -i en0 (or en1), but the Mac ignores them and doesn't send a
> DHCPREQUEST.  There is only one peculiarity about the OFFERS that I
> can see.  They do NOT have the broadcast flag set, but they are being
> sent to the all-ones broadcast addresses FF:FF:FF:FF:FF:FF /
> 255.255.255.255 due to how the relay agent is configured.  The relay
> agent needs to always broadcast in order to work at all (the
> implementation of the relay agent in the router can't lookup/add a
> route to the layer 2 destination from the layer 3 interface in order
> to unicast the DHCPOFFERs/DHCPACKs to the clients).  This doesn't
> cause a problem with any other clients, and like I said, even other
> Macs are working.
> 
> I'd appreciate any advice/knowledge on how to troubleshoot the DHCP
> client in Mac OS.  Searching the Apple support forums, other internet
> forums, and mailing list posts (including archives of this list) has
> proved fruitless so far.
> 
> Thanks,
> Chuck
howdy Chuck,

where is the dhcp server ?

what is your network topology ?

dhcp packets are pretty much headless and utterly dumb packets ( UDP ).  can you verify that your DHCP server is within the same Subnet and Vlan as your client ? 
If not, you may need what is called a DHCP helper /UDP helper within your switch gear. It basically tells the return packet where your dhcp relay server is located.

If the server is local, and the packets are being received on the correct interface, you may need to inspect the DHCP server scope for that subnet. be advised, OSX 10.6 + server runs a bootpd server.
man bootpd
osx does not use isc's dhcpd server anymore, unless you build it yourself, building is easy.
-j