bgp_next_hop check?

[Maria Jan Matějka]

On May 29, 2018 8:42:22 PM GMT+02:00, Job Snijders <job at instituut.net> wrote:
>Dear BIRD devs,
>
>On https://gitlab.labs.nic.cz/labs/bird/wikis/BGP_filtering I see the
>following curious snippet:
>
>    function xx()
>    {
>        ...
>        if bgp_next_hop != from then return false;
>        ...
>    }
>
>What in the above example does "from" mean? Is "from" some kind of
>magic
>keyword that expands into something?

Yes. It expands to the author of the route (IP of its sender). Therefore this check is to filter out routes with other next hop than the sender herself as this is probably some scam or misconfiguration.

Maria