OSPF Neighbor Authentication

Neighbor authentication is pretty straightforward, there is a clear text and md5 option. I show the md5 option, clear test is similar just minus the md5 stuff in the command. Adjacencies will break when setting up authentication.

R1(config-if)#ip ospf authentication message-digest

R1(config-if)#ip ospf message-digest-key 1 md5 CCNP

R1(config-if)#
R1#
*Mar  1 01:03:18.335: %SYS-5-CONFIG_I: Configured from console by console
*Mar  1 01:03:23.375: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on Serial0/0 from FULL to DOWN, Neighbor Down: Dead timer expired
*Mar  1 01:03:35.407: %OSPF-5-ADJCHG: Process 1, Nbr 3.3.3.3 on Serial0/0 from FULL to DOWN, Neighbor Down: Dead timer expired

R2(config)#interface serial 0/0

R2(config-if)#ip ospf authentication message-digest

R2(config-if)#ip ospf message-digest-key 1 md5 CCNP

R3(config)#int serial 0/0

R3(config-if)#ip ospf message-digest-key 1 md5 CCNP

R3(config-if)#ip ospf authentication message-digest

R1#show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface

2.2.2.2           0   FULL/DROTHER    00:01:46    172.12.123.2    Serial0/0

3.3.3.3           0   FULL/DROTHER    00:01:58    172.12.123.3    Serial0/0