iMac refuses to accept IP

[Peter Rathlev]

On Wed, 2012-06-27 at 13:55 +0200, Siegenthaler Tina wrote:
...
> New iMac (not accepting IP):
...
>     Option: (t=61,l=33) Client identifier
>         Option: (61) Client identifier
>         Length: 33
>         Value: 013C075472CBC20000000000000000000000000000000000...
...
> 
> "Older" iMacs (OK):
...
>     Option: (t=61,l=7) Client identifier
>         Option: (61) Client identifier
>         Length: 7
>         Value: 01C82A140F0D27
>         Hardware type: Ethernet
>         Client MAC address: c8:2a:14:0f:0d:27 (c8:2a:14:0f:0d:27)

Can you capture the second discover from the new client and take a look
at the Client Identifier? My guess is that the second packet contains a
7 byte CI (just like the older clients) consisting of 0x01 and the MAC
address (013C075472CBC2). The value above seems to be those 7 bytes and
then 26 bytes of zero, which is not the same.

Client Identifier is always the key from the server's perspective. If CI
changes it's a new host. This is mandatory per RFC2131/RFC4361.

If that's the problem there is no DHCP compliant way of solving the
problem other than changing what the client sends as CI.

-- 
Peter