Configuring OSPF authentication

Three types of authentication
- none (default)
- plain text
- MD5 hash

OSPF authentication is configured at interface level, interconnected routers need to have authentication enabled on appropriate interfaces, with same auth.

Authentication mis-match:
*Mar 1 00:04:27.851: OSPF: Rcv pkt from 192.168.2.1, FastEthernet0/0 : Mismatch Authentication type. Input packet specified type 0, we use type 2

OSPF with MD5 hash authentication:

!interface FastEthernet0/0
ip address 192.168.2.1 255.255.255.0
ip ospf authentication message-digest
ip ospf authentication-key mysecret
duplex auto
speed auto

Debug ip ospf adj - troubleshoot authentication problems