- OSPF Supports authentication against routing injection.
- Every Hello, Update, LSR includes authentication info.
Auth Types:
- Type 0 – Null
- Type 1 – Simple
- Type 2 – MD5/SHA
Configuration:
- OSPF Process
- area <#> authentication
- Link Level
- ip ospf authentication
- Overrides global process
- ip ospf authentication
- Password always configured on the link
- ip ospf authentication-key
- ip ospf message-digest key
- Key IDs must obviously match.
- Virtual Link
- Area 0 Interface
- Inherits rules of authentication
- Key goes at the interface.
- Type can be configured globally or at interface.
- Runs as demand circuit.
Examples:

Authentication between R4 and R5 Area 0:




This can be confirmed with the ospf interface command:
