Sten Carlsen sten at s-carlsen.dk
Thu Feb 12 21:04:34 UTC 2009

Dean, Barry wrote:
> Client comes along with a DHCPREQUEST for the dynamic IP and the log says:
> DHCPREQUEST for from 00:31:72:73:c8:c9 via e1000g0: lease unavailable.
> DHCPNAK on to 00:31:72:73:c8:c9 via e1000g0
> The client keeps using the IP until the lease expires, then starts a DHCPDISCOVER etc.
> I can truss the dhcpd process and see the packets being read by recvfrom(), but NOTHING appears in the log and NOTHING happens. Poor client keeps trying until it gives up.
> The server has simply stopped responding.
If I am not mistaken the client should issue the DHCPDISCOVER as soon as
it does not any longer have a valid address (DHCPNACK).

>From rfc2131:
      If the client receives a DHCPNAK message, it cannot reuse its
      remembered network address.  It must instead request a new
      address by restarting the configuration process, this time
      using the (non-abbreviated) procedure described in section
      3.1.  This action also corresponds to the client moving to
      the INIT state in the DHCP state diagram.

So to me it looks like the client is at fault, not the server. Or the
client never receives the DHCPNACK and therefore does not see that it's
address is no longer valid.

Best regards

Sten Carlsen

No improvements come from shouting:


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