Hello Peter:

Could you please identify what version of "dhcpd" this was working under and what you are using now?  Examining our code it appears to me the ISC DHCP has never supported option 209, though its specification exists in our.  It is currently compiled out as you can see in the excerpt from common/tables.c below:

  :
#if 0
    /* PXELINUX options: defined by RFC 5071 */
    { "pxelinux-magic", "BBBB",     &dhcp_universe, 208, 1 },
    { "loader-configfile", "t",     &dhcp_universe, 209, 1 },
    { "loader-pathprefix", "t",     &dhcp_universe, 210, 1 },
    { "loader-reboottime", "L",     &dhcp_universe, 211, 1 },
#endif
   :

As near as I can determine we have never shipped a version with this compiled in or with the option name as "configfile".  Most likely you were running a patched or packaged version, not produced by ISC.

If you're willing to build from our source and require only that the option be parsed and sent back by the server, you could change the "#if 0" to "#if 1" in the file above and rebuild.  If you decide to go this route I would encourage you to use the option labels as they are above: "loader_configfile" rather than "configfile". In the event we begin shipping with these compiled in, you'll be compatible with our source.

In the meantime, I will look into whether or not we should compile these options in by default.  RFC 5071 was finalized a long time ago (2007) and I need to dig into why these options were not included by default at that time.  It may be simple oversight but DHCP protocol evolution sometimes holds obscurities and it seldom pays to make assumptions.


Regards,

Thomas Markwalder
ISC Software Engineering