1. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-1 Implementing a Scalable Multiarea Network OSPF- Based Solution Configuring and Verifying OSPF Authentication

2. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-2 OSPF Authentication Types  OSPF supports two types of authentication: –Simple password (or plaintext) authentication –MD5 authentication  The router generates and checks every OSPF packet.  The source of each routing update packet received is authenticated.  Each participating neighbor must have the same key (password) configured.

3. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-3 Configure Simple Password Authentication for OSPF  This command defines a password to be used with a neighboring router.  The neighboring router must have the same password configured.  Specifies the authentication type for an interface or the authentication type for an area. R1(config-if)#ip ospf authentication-key mykey R1(config-if)#ip ospf authentication OR R1(config-router)#area 0 authentication

4. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-4 Simple Password Authentication Configuration Example

5. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-5 Simple Password Authentication Configuration for Virtual Links

6. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-6 Verifying Simple Password Authentication

7. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-7 Configure OSPF MD5 Authentication  Defines a key ID and key to be used with a neighboring router.  Neighboring router must have the same combination of key ID and key configured.  Specifies the authentication type for an interface or the authentication type for an area. R1(config-if)#ip ospf message-digest-key 1 md5 mysecretkey R1(config-if)#ip ospf authentication message-digest OR R1(config-router)#area 0 authentication message-digest

8. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-8 OSPF MD5 Authentication Configuration Example

9. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-9 Verifying MD5 Authentication

10. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-10 Authentication Verification Problems include the following:  Authentication problems: –Authentication is not configured on both sides. –A different authentication type is configured on either side.  Different passwords are configured on either side. debug ip ospf adj R1#  This command displays the OSPF adjacency-related events.

11. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-11 Successful Simple Password Authentication Verification  Authentication is configured correctly

12. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-12 Troubleshooting Simple Password Authentication Problems  Simple authentication is not configured on router R2  Different keys on routers R1 and R2

13. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-13 Successful MD5 Authentication Verification  Authentication is configured correctly

14. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-14 Troubleshooting MD5 Authentication Problems  MD5 authentication configured on both routers  Router R1 has key 1 and router R2 has key 2, both with the same passwords:

15. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-15 Summary  When authentication is configured, the router generates and checks every OSPF packet and authenticates the source of each routing update packet that it receives. OSPF supports two types of authentication: –Simple password (or plaintext) authentication: The router sends an OSPF packet and key. –MD5 authentication: The router generates a message digest, or hash, of the key, key ID, and message. The message digest is sent with the packet; the key is not sent.  To configure simple password authentication, use the ip ospf authentication-key password command and the ip ospf authentication command.

16. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-16 Summary (Cont.)  To configure MD5 authentication, use the ip ospf message- digest-key key-id md5 key command and the ip ospf authentication message-digest command.  Use the show ip ospf neighbor, show ip route, ping, and debug ip ospf adj commands to verify and troubleshoot both types of authentication. With MD5 authentication, the debug ip ospf adj command output indicates the key ID sent.

17. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-17