OSPF with OpenBSD

bsd/ospf | bsd/ospf-n-bgp | bsd/bgp | cisco/ospf | cisco/ospf-n-bgp | cisco/bgp

assuming kvm/obsd gns3 guests

Here we have three OSPF routers sharing a single area, and with a global default route.

Router IDs (type Router) do not need to have a true IP on the wire. Those do not conflict with routed IPs (type Network).

There’s no default route defined on any router here but on router2.

Requirements

Enable forwarding

sysctl net.inet.ip.forwarding=1
echo net.inet.ip.forwarding=1 >> /etc/sysctl.conf

Netprep

vpcs*

ip 10.0.0.1/24 10.0.0.254
ip 10.3.3.1/24 10.3.3.254
save

workstation (libvirt)

no need for static routes because we’re doing NAT within the PoC (on router2)

router*

hostname router1
hostname router2
hostname router3

    vi /etc/myname

router1
router2
router3

    vi /etc/hostname.vio0

inet 10.1.1.1/24
inet 10.1.1.254/24
inet 10.2.2.1/24

    vi /etc/hostname.vio1

inet 10.0.0.254/24
inet 10.2.2.254/24
inet 10.3.3.254/24

# router2 only --- gateway gets defined there
vi /etc/hostname.vio2

dhcp

ls -lF /etc/mygate # no exist

apply network setup

sh /etc/netstart

OSPF

router*

vi /etc/ospfd.conf

# router1
router-id 1.1.1.1
redistribute connected

area 0.0.0.0 {
        interface vio0
}

# router2 has a default route
router-id 2.2.2.2
redistribute connected
redistribute default

area 0.0.0.0 {
        interface vio0
        interface vio1
}

# router3
router-id 3.3.3.3
redistribute connected

area 0.0.0.0 {
        interface vio0
}

chmod 600 /etc/ospfd.conf

make sure there’s NO DEFAULT GATEWAY defined but on router2

netstat -rn -f inet

you will need your own nat for all your networks to reach virbr0 (192.168.122.0/24)

router2 only

    mv /etc/pf.conf /etc/pf.conf.dist
    vi /etc/pf.conf

pass out on vio2 from 10.0.0.0/24 to any nat-to (vio2)
pass out on vio2 from 10.1.1.0/24 to any nat-to (vio2)
pass out on vio2 from 10.2.2.0/24 to any nat-to (vio2)
pass out on vio2 from 10.3.3.0/24 to any nat-to (vio2)

pfctl -nf /etc/pf.conf
pfctl -f /etc/pf.conf

Operations

try it once in debug mode

ospfd -d
^C

enable at boot-time and start

tail -f /var/log/daemon
rcctl enable ospfd
rcctl start ospfd

check status and terminate

rcctl check ospfd
rcctl stop ospfd

Acceptance

show your neighbors, shared and aquired routes

ospfctl show neighbor
ospfctl show rib
ospfctl show fib ospf

then ping a leaf node from one side of the network to another, and also try to reach the public network to some DNS open relay that actually conflicts with some of our router IDs (does NOT conflict)

vpcs1

ping 10.4.4.1
trace 10.4.4.1

ping 1.1.1.1
trace 1.1.1.1

Additional notes

in case you’re having your own workstation instead e.g. the left-hand leaf node, you need to tune the routes as it has a better default route already.

(linux)

ip route add 10.0.0.0/24 via 192.168.122.X
ip route add 10.1.1.0/24 via 192.168.122.X
ip route add 10.2.2.0/24 via 192.168.122.X
ip route add 10.3.3.0/24 via 192.168.122.X

enabling auth between routers

        interface xnf0 {
            auth-type simple
            auth-key PASSWORD-HERE
        }

Resources

ospfd.conf — Open Shortest Path First daemon configuration file https://man.openbsd.org/ospfd.conf.5

OpenBGPD Presentations and Papers http://www.openbgpd.org/papers.html

Routing with OpenBSD https://www.openbsd.org/papers/linuxtag06-network/index.html

OpenBSD FAQ - Networking https://www.openbsd.org/faq/faq6.html

OpenBSD FAQ - System Management https://www.openbsd.org/faq/faq10.html

guides

Howto OSPF sous OpenBSD https://wiki.evolix.org/HowtoOpenBSD/OSPF

VPLS basic test setup https://github.com/rwestphal/openbsd-ldpd/wiki/VPLS-basic-test-setup

Configure Some Basic OSPF Routing Scenarios https://www.alliedtelesis.com/sites/default/files/documents/configuration-guides/howto_aw-_config_basic_ospf_routing_revd.pdf

How to configure OSPF Default Route https://networklessons.com/ospf/how-to-configure-ospf-default-route