BFD socket bind error upon reboot

[Ondrej Zajicek]

On Fri, Aug 10, 2018 at 11:23:56PM +0200, J. Kendzorra wrote:
> Hi,
> 
> upon a reboot of a system running BFD I recently noticed BFD breaking
> with error "Cannot assign requested address" once the system came back.
> Restarting the BFD protocol in question solved the problem.
> Hence, apparently the system's network wasn't fully up and running at
> the time bird started; according to systemd documentation
> (https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget/), one
> possible fix is to change bird.service from
> After=network.target
> to
> After=network-online.target
> Wants=network-online.target
> Alternatively, IP_FREEBIND on the BFD tx socket would allow binding to
> an IP address that does not (yet) exist which seems more elegant since
> it doesn't need to take into account that different systems may define
> "online" differently.
> I'm wondering whether there's something I'm missing as to why
> IP_FREEBIND shouldn't be used?

Hi

Generally, BIRD should not try to use an address before it notices that
the address is available/active. If BIRD tries to bind the socket before
that, then it is a bug.

Which BIRD version it is? It is an IPv6 address? Which protocol caused
the BFD session or it is static one? I would suspect that the issue
is related to IPv6 DAD.

-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
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"To err is human -- to blame it on a computer is even more so."