weird routes apparing in linux cache route table

16 Dec 2012

      Hi,

Linux 3.0.18 (using multiple routing tables with priorities set via ip rule 
but that's not relevant here I guess), bird 1.3.8 and weird problem.

I have simple bird configuration, only one bgp peer. I'm NOT
exporting received routes to kernel:

protocol kernel {
        learn;
        export none;
        import all;
        scan time 15;
}

Now the problem is that there ARE weird routes (for IP X) are appearing in 
kernel cache table (and not any other) for routes that are received by bird.

The weird routes are appearing when openvpn client connects to the same 
machine from IP X address.

Cached routes are like this:
IP_X from My_IP dev eth0

If I disable protocol bgp {} section then the problem goes away. I enable it, 
"configure" and problem reappears.

Why bird has influence on linux kernel cache routing table if export none? No 
clue.

Any ideas?

config:

router id xxx...;

filter bgp_in_net
prefix set PS;
{
        accept;
}

filter bgp_out_net
prefix set PS;
{
        PS = [ something/24 ];
        if ( net ~ PS ) then accept;

        reject;
}

protocol device {
        scan time 10;
}

protocol direct {                
        interface "eth0";
}

protocol direct {                   
        interface "eth1";
}

protocol kernel {
        learn;
        export none;
        import all;
        scan time 15;
}

protocol bgp netia {
        debug { states, events };
        description "net";
        import filter bgp_in_net;
        export filter bgp_out_net;

        local as aaaa;
        neighbor bbbbbb as cccc;
        default bgp_local_pref 100;
}
-- 
Arkadiusz Miśkiewicz, arekm / maven.pl