OSPF Basic Authentication
r1(config)#interface fastethernet x/x
r1(config-if)#ip ospf authentication
r1(config-if)#ip ospf authentication-key itss
r2(config)#interface fastethernet x/x
r2(config-if)#ip ospf authentication
r2(config-if)#ip ospf authentication-key itss
OSPF Encrypted Authentication
r1(config)#interface fastethernet x/x
r1(config-if)#ip ospf authentication message-digest
r1(config-if)#ip ospf message-digest-key 1 md5 itss
r2(config)#interface fastethernet x/x
r2(config-if)#ip ospf authentication message-digest
r2(config-if)#ip ospf message-digest-key 1 md5 itss
OR
(config)#router ospf #
(config-router)#area # authentication message-digest
(config-router)#exit
(config)#interface serial X
(config-if)#ip ospf message-digest-key 1 md5 itss
Verifying OSPF connectivity
Ping interface ip addresse
Show ip ospf neighbor
Show ip ospf interface fastethernet
