DHCPD and Windows question

[Dan Jenkins]

On 2/14/2010 12:26 PM, Todd Littlefield wrote:
>  I finally got some time to sit down with Wireshark and compare the
>  bootp packets between the D-Link and the Linux box...  The first
>  thing that jumped out as different was the source address on the DHCP
>  Offer packets.
>
>  D-Link:  192.168.1.1 Linux:     127.0.0.1
>
>  So, something wasn't right.  I began mucking around with a bunch of
>  different settings based on the dhcpd.conf(5) pages.  None seemed to
>  work...
>
>  After looking a little closer at the server-identifier tag, it was
>  misconfigured...  I was using the name instead of IP address.  The
>  man pages are a bit confusing though...  It states:
>
>  Theserver-identifier  statement
>
>  *server-identifier*  hostname*;*
>
>  The  server-identifier statement can be used to define the value
>  that is sent in the DHCP Server Identifier option for a given scope.
>  The value  specified*must*  be an IP address for the DHCP server, and
>  must be reachable by all clients served by a particular scope.
>
>
>
>  So, it needs to be set to the --hostname-- but they really mean
>  --IP--  Why they didn't just specify it as:
>
>
>  Theserver-identifier  statement
>
>  *server-identifier*  *address;*
>
>
>  I guess we will never know...  Right below that is the server-name
>  tag, which really is the name.  So, if anyone else runs into this
>  problem, the answer is RTFM --Carefully-- before adding things to the
>  config.

In the man page for dhcpd.conf, after the paragraph above, it says:
>  The use of the server-identifier statement is  not  recommended  -
>  the  only  reason  to  use  it  is to force a value other than the
>  default value to be sent on  occasions  where  the  default  value
>  would  be  incorrect.    The default value is the first IP address
>  associated with  the  physical  network  interface  on  which  the
>  request arrived.
>
>  The  usual  case where the server-identifier statement needs to be
>  sent is when a physical interface has more than  one  IP  address,
>  and  the  one  being sent by default isn't appropriate for some or
>  all clients served by that interface.  Another common case is when an
>  alias  is  defined  for  the purpose of having a consistent IP
>  address for the DHCP server, and it is desired  that  the  clients
>  use this IP address when contacting the server.

So, you would not normally use it at all. I've never had a reason to use 
it myself.

I suspect, if you had an entry in /etc/hosts mapping your desired IP to 
that hostname,
and used that hostname in server-identifier, it would work. An IP 
derived from a DNS
lookup wouldn't, however.

--
Dan Jenkins, Rastech Inc.