dhclient and custom Linux routing tables (VRF)

Simon Hobson dhcp1 at thehobsons.co.uk
Sat Jun 8 18:51:58 UTC 2019

Bill Shirley <bill at c3po.polymerindustries.biz> wrote:

> One thing that bugs me about Debian's dhclient (might be an Ubuntu thing) is that
> if the server sends both option router (3) and option static-routes (33), the script
> implements the static-routes but ignores router.  
> /sbin/dhclient-script:
>             # if we have $new_rfc3442_classless_static_routes then we have to
>             # ignore $new_routers entirely

It's called "standards compliancy" !
The comment conveniently references the RFC where this behaviour is mandated - ie if the classless static routes option is supplied (and used by the client) then the client MUST ignore both the default router and static routes options.
That does make sense - otherwise there could be all sorts of complications.

You can, if you wish, ignore (or just not ask for) the classless static routes option and just install the default router - but then you'd be throwing away useful configuration information.

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