'RE: RE: Meaning of logmessages'

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List:       dhcp-users
Subject:    RE: RE: Meaning of logmessages
From:       "Friesen, Don LCTZ:EX" <Don.Friesen () gov ! bc ! ca>
Date:       2011-09-28 16:35:27
Message-ID: 38CB0471281C6C4EB6F3A7F885868EA934C9AAA2 () e7mbx24 ! idir ! bcgov
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> 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.

Don Friesen
Technical Services 
Enterprise-Wide Application Services, Corporate Application Services
Shared Services BC, Technology Solutions
Ministry of Labour, Citizens' Services and Open Government
4000 Seymour Place  -  E253 

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