OSPF MD5 Authentication Configuration Guide | Explained with Examples

OSPF MD5 Authentication Configuration Guide | Explained with Examples

You can enable authentication in OSPF in order to exchange routing update information in a secure manner.
OSPF authentication can either be none (or null), simple, or MD5.
The authentication method "none" means that no authentication is used for OSPF and it is the default method.
With simple authentication, the password goes in clear-text over the network.
With MD5 authentication, the password does not pass over the network. MD5 is a message-digest algorithm specified in RFC 1321.
MD5 is considered the most secure OSPF authentication mode.
When you configure authentication, you must configure an entire area with the same type of authentication.

These are the three different types of authentication supported by OSPF.
1. Null Authentication — This is also called Type 0 and it means no authentication information is included in the packet header. It is the default.
2. Plain Text Authentication — This is also called Type 1 and it uses simple clear-text passwords.
3. MD5 Authentication — This is also called Type 2 and it uses MD5 cryptographic passwords.

CONFIGURE:
R1:
conf t
interface gig 0/0'
ip ospf message-digest-key 1 md5 cisco
ip ospf authentication message-digest !Enable plain text authentication at the interface level.
end
wr

R2:
conf t
interface gig 0/0
ip ospf message-digest-key 1 md5 cisco
ip ospf authentication message-digest !Enable plain text authentication at the interface level.
end
wr

R1:
conf t
router ospf 1
area 0 authentication message-digest !MD5 authentication is enabled for all interfaces in Area 0.
end
wr

R2:
conf t
router ospf 1
area 0 authentication message-digest !MD5 authentication is enabled for all interfaces in Area 0.
end
wr

VERIFY:
debug ip ospf adj
show ip ospf neighbor
show ip ospf interface G0/0
show ip route

REFERENCES:

Sample Configuration for Authentication in OSPF

IP Routing

OSPF: Frequently Asked Questions

Important Information on Debug Commands

#cisco #ccnp #ccie #ospf

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