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Re: Debian installer dhcp problems



Camaleón wrote:
> Bob Proulx wrote:
> > It may be unintuitive but ignoring client identifier is incorrect. That
> > is why patching to do so isn't accepted upstream.  Ignoring client
> > identifier violates the protocol.  See RFC 2131.
> 
> Yes, I guess that's what man page also warns about, so what's the point 
> in adding a setting that in the end cannot be honored? :-?

What do you mean, cannot be honored?  Why can't it be honored?  And in
fact it does honor it.  It works exactly as described.  (confused)

> ***
> The duplicates flag tells the DHCP server that if a request is received
> from a client that matches the MAC address of a host  declaration,  any
> other  leases  matching  that  MAC  address  should be discarded by the
> server, even if the UID is not the same.   This is a violation  of  the
> DHCP  protocol, but can prevent clients whose client identifiers change
> regularly from holding many leases  at  the  same  time.   By  default,
> duplicates are allowed.
> ***

Wow.  It is now an option in the upstream as "deny duplicates;".  I
did not know it was now available there as an upstream option.  I will
have to try it and see how it works!

But frankly I have never needed it.  There are a large number of
private addresses available.  I have just always made sure I had a
large enough pool that it did not matter.

A brief search turned up this reference that describes some problems
with ignoring the client identifier and the workarounds they
implemented in order to workaround the workarounds.

  http://www.net.princeton.edu/announcements/dhcp-cliid-must-match-chaddr.html

I think it is better simply to have enough IP addresses in the pool
and then not worry about it.

> I mean, the patch is aimed to solve something that is currently there but 
> is not working or did I miss something?

Actually it was I who did not realize that the patch is now in the
upstream as "deny duplicates".  And not knowing about it I haven't
tried it.  Will need to test it.

> Hum... I was not aware this was part of that well-know-discussed issues, 
> but regardless its "awareness status", is something that should addressed 
> at dhcp mailing list. I think is a valid concern for users and they 
> deserve a proper response, whatever it be.

I admit to not knowing but it seems to me that the response must have
been the addition of "deny duplicates;".  Assuming that does what it
says it does in the documentation.

Bob

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