Deleting IPv4 iface-routes from extra FIBs

[Nikolay Denev]

On Tue, Apr 22, 2014 at 5:37 PM, Harald Schmalzbauer
<h.schmalzbauer at omnilan.de> wrote:
> Hello,
>
> here, http://svnweb.freebsd.org/base?view=revision&revision=248895
> interface route protection was added (so the following problem arose
> with 9.2).
>
> Unfortunately, in my case, I must be able to delete these routes; not in
> the default FIB, but in jail's fibs, because:
> · Host is multihomed with multiple nics in different subnets.
> · Jail's IP (no vnet) is from a different subnet than host's
> default-router subnet – jail has no ip in the range of host's
> default-router!!!
> · FIB used by jail contains valid default-router.
>
> Problem:
> If iface-routes exist in jail's FIB, answer-packets take the
> iface-shortcut, not trespassing the router (default gateway); hence
> 3way-handshake never finishes and firewall terminates (half-opened) TCP
> sessions.
>
> Workarround:
> · Abuse packet filter doing some kind of route-to…
> · Revert r248895, to be able to delete v4-iface-routes (inet6-routes can
> be deleted without any hack)
>
> Desired solution:
> · Allow deletion of v4-iface-routes if FIB!=0.
>
> Unfortunately my C skills don't allow me to implement this myself :-(
> I can't even follow the code, I guess that was originally considered,
> but possibly doesn't work bacause of a simple bug?!? I took the lazy way
> and simply reverted r248895 instead of trying to understand
> rtrequest1_fib(). I wish I had the time to learn…
>
> Thanks for any help,
>
> -Harry
>

Hi,

As it was suggested before as immediate workaround you can set
net.add_addr_allfibs=0 so that the interface routes are added only in
the default FIB.

--Nikolay