Cannot connect two ospf-instances over tun-interface

[dawid k]

Hi Chris,

Thank you for your advice, I got a little bit forward.

I expended my topology with another pc - another vpn client - and I got
these two vpn clients working, but somehow I cannot get the server to work
properly. The server remains always in state  Init/Other.

I can see with tcpdump, that every pc is sending the hello-message, but the
server is missing the neighbor list:


08:48:55.791063 IP (tos 0xc0, ttl 1, id 15221, offset 0, flags [none],
proto OSPF (89), length 64)
server > ospf-all.mcast.net: OSPFv2, Hello, length 44
        Router-ID 10.29.0.1, Backbone Area, Authentication Type: none (0)
        Options [External]
          Hello Timer 10s, Dead Timer 40s, Mask 255.255.252.0, Priority 1
          Designated Router 10.29.0.1
08:49:02.449351 IP (tos 0xc0, ttl 1, id 6717, offset 0, flags [none], proto
OSPF (89), length 72)
    10.29.0.8 > ospf-all.mcast.net: OSPFv2, Hello, length 52
        Router-ID 192.168.21.1, Backbone Area, Authentication Type: none (0)
        Options [External]
          Hello Timer 10s, Dead Timer 40s, Mask 255.255.252.0, Priority 1
          Designated Router 10.29.0.4, Backup Designated Router 10.29.0.8
          Neighbor List:
            192.168.21.17
            10.29.0.1
08:49:02.854749 IP (tos 0xc0, ttl 1, id 9690, offset 0, flags [none], proto
OSPF (89), length 72)
    10.29.0.4 > ospf-all.mcast.net: OSPFv2, Hello, length 52
        Router-ID 192.168.21.17, Backbone Area, Authentication Type: none
(0)
        Options [External]
          Hello Timer 10s, Dead Timer 40s, Mask 255.255.252.0, Priority 1
          Designated Router 10.29.0.4, Backup Designated Router 10.29.0.8
          Neighbor List:
            192.168.21.1
            10.29.0.1

Here the output from  birdc show ospf neighbors on client:

Router ID       Pri          State      DTime   Interface  Router IP
192.168.21.17     1     Full/DR         00:35   tun0       10.29.0.4
10.29.0.1         1     Init/Other      00:38   tun0       10.29.0.1

and finally my ospf-setup for every device:


protocol ospf myOSPFX { # X depending on device (1,2,3)
        debug all;
        import filter importAll;
        export filter onlyLocalExport;
        area 0.0.0.0 {
                interface "tun0" {
                        cost 10;
                        type  bcast;
                        stub no;
                        hello 10;
                        transmit delay 5;
                        wait 10;
                        dead 40;
                 };
       };
}

Do you have any idea, what I'm missing?














2018-04-03 16:52 GMT+02:00 Chris Boot <lists at bootc.boo.tc>:

> [re-sending to the list with the correct From address]
>
> Hi,
>
> You should be able to do this with 'topology subnet' on your server end.
> It doesn't work with net30 (the default) or p2p, but I can confirm that
> OSPFv2 for IPv4 works in broadcast mode with 'topology subnet'.
>
> I think there are issues with IPv6 on tun links with respect to
> multicast, so you may struggle to get OSPFv3 working, but I haven't had
> to do that yet.
>
> HTH,
> Chris
>
> On 03/04/18 15:34, dawid k wrote:
> > Therefore I tried running ospf in broadcast mode as well, but then it
> > changed automatically:
> >
> > <WARN> myOSPF3: Cannot use interface tun0 as broadcast, forcing ptp
> >
> > I tried the tap-Interface and it's working (or at least the neighbours
> > were detected) but as said, my system has to use tun and I cannot change
> > it. So there is propably no solution for such settings. I will try bgp
> > instead. Thank you for your help.
> >
> > 2018-04-03 16:18 GMT+02:00 Ondrej Zajicek <santiago at crfreenet.org
> > <mailto:santiago at crfreenet.org>>:
> >
> >     On Tue, Apr 03, 2018 at 08:05:41AM -0600, Michael McConnell wrote:
> >     > OpenVPN won’t do multicast over TUN, only TAP.
> >
> >     Well, that would be silly from OpenVPN. But tcpdump output from
> Dawid K
> >     shows that multicast packets are propagated throught TUN:
> >
> >     > 06:59:00.439738 IP (tos 0xc0, ttl 1, id 15270, offset 0, flags
> [none], proto OSPF (89), length 64)
> >     >     server > 224.0.0.5 <http://224.0.0.5>: OSPFv2, Hello, length
> 44
> >     >         Router-ID repo.traffic.local, Backbone Area,
> Authentication Type: none (0)
> >     >         Options [External]
> >     >           Hello Timer 10s, Dead Timer 40s, Mask 0.0.0.0, Priority 1
> >     > 06:59:02.449363 IP (tos 0xc0, ttl 1, id 18875, offset 0, flags
> [none], proto OSPF (89), length 64)
> >     >     10.29.0.6 > 224.0.0.5 <http://224.0.0.5>: OSPFv2, Hello,
> length 44
> >     >         Router-ID 192.168.21.17, Backbone Area, Authentication
> Type: none (0)
> >     >         Options [External]
> >     >           Hello Timer 10s, Dead Timer 40s, Mask 0.0.0.0, Priority 1
> >
> >     --
> >     Elen sila lumenn' omentielvo
> >
> >     Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org
> >     <mailto:santiago at crfreenet.org>)
> >     OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3,
> >     wwwkeys.pgp.net <http://wwwkeys.pgp.net>)
> >     "To err is human -- to blame it on a computer is even more so."
> >
> >
>
>
> --
> Chris Boot
> bootc at boo.tc
>
> --
> Chris Boot
> bootc at boo.tc
>
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