Option 43 and missing options

Peter Rathlev peter at rathlev.dk
Wed Sep 12 13:01:55 UTC 2018

On Wed, 2018-09-12 at 07:19 -0500, Ryan Gray wrote:
> I am sure that this works on the server. That is not because I found
> it in the documentation, but just based on seeing it myself. 

Well something doesn't work, otherwise I assume you wouldn't have
posted the first email. :-)

My point was since I cannot find "append" anywhere in the man pages for
current versions of the server, then maybe that's just not a supported
thing and it could be wrecking havoc. A bug, yes, but only something
that appears when configuring non-supported things.

Searching the interwebs I found this:


Almost exactly the same problem as yours: Using "append" to add option
15 makes options 1, 3 and 6 disappear. No answers to that one though.

Also see this:


Maybe "append" was a dhcpd 3.x thing?

> When the "append dhcp-parameter-request-list" and the "option vendor-
> encapsulated-options...." are included in the config block for that
> subnet, 3, 6, and 28 are just not sent.    That was, until I added
> the line "append dhcp-parameter-request-list 3", then one for 6 and
> another for 28. I suspect these aren't the only options missing, but
> the only ones I'm caring about today.
> I agree this behavior seems odd. That said, I have proven, at least
> here, that these changes fix the issue. This seems like one of those
> murky things that's going to manifest again during an upgrade or
> other system change. :)

My guess is that using the documented "concat" function will actually
solve your problem of disappearing options. I'm guessing this since we
use it that way and are not missing any options.


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