Meaning of logmessages
Friesen, Don LCTZ:EX
Don.Friesen at gov.bc.ca
Wed Sep 28 16:35:27 UTC 2011
> The RFC states:
> > The server SHOULD check the network address in a DHCPINFORM
> > message for consistency, but MUST NOT check for an existing
> > lease.
> That seems to be taken to mean that no configuration information should
>be taken from an existing lease even if one exists. I suppose it does not
>forbid using static configuration taken from any host entry (or parent
>group) the IP address or ethernet address may map to but that could easily
>map to multiple, conflicting sets of parameters. What do you do if the
>DHCPINFORM request from a chaddr specifies an IP address different from
>the one the server would give it?
Other bits from the RFC:
> The server forms a DHCPACK message containing the configuration
> parameters for the requesting client and sends the DHCPACK message
> directly to the client.
> 4.3.5 DHCPINFORM message
> The server responds to a DHCPINFORM message by sending a DHCPACK
> message directly to the address given in the 'ciaddr' field of the
> DHCPINFORM message. The server MUST NOT send a lease expiration time
> to the client and SHOULD NOT fill in 'yiaddr'. The server includes
> other parameters in the DHCPACK message as defined in section 4.3.1.
Section 4.3.1 outlines the response to a DHCPDISCOVER, but includes the MUST, MUST NOT, MAY, and SHOULD behaviour for a DHCPACK.
My point is that regardless of the existence of a lease, the server should at least be consistent with the contents of the DHCPACK messages it sends to its own clients. If a client has obtained parameters from the server via a DHCPACK that is in response to a DHCPREQUEST, then the DHCPACK that is sent in response to a DHCPINFORM should be consistent.
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