What DHCP Option Tells the DHCP Server the Client's Host name?

Martin McCormick martin at dc.cis.okstate.edu
Sun Jan 20 20:23:41 UTC 2008

Glenn Satchell writes:
> You can use syntax sych as:
> set myclientid = option dhcp-client-identifier;
> and it will add this variable to the lease structure in dhcpd.leases.
> The client identifier is set by MS windows dhcp clients as a '1'
> followed by the mac address. Most other dhcp clients do not set it at
> all.
> Have a look at the dhcp-options man page for a list of the names of the
> various options. dhcp-eval man page has the bits for manipulating
> them.
> The value you want to read is 'option hostname'.

	I think I am missing something, here.

	Our production DHCP server pair sets a vendor-class
variable exactly as you describe for putting Cisco telephones in
their proper class and it shows up in thedhcpd.leases file just
as you describe. I also see something else in each lease that
has a client computer name that I do not see on the test setup.

  set ddns-fwd-name = "GINGER.cdsw1.osu";
  set vendor_class = "MSFT 5.0";
  client-hostname "GINGER";

That last line is exactly what I need to look at, but my test
setup doesn't either show it in the syslog nor place a line like:

  client-hostname "GINGER";

	I am also not even looking for the client's hostname on
the production boxes but, as you see, it put it in the lease.

	The only difference between the production server pair
and the test dhcp server is that the test dhcp server is a
stand-alone DHCP server.

	It almost looks like there is more than one way the
client sends its host name to dhcpd.

Martin McCormick

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