How to Configure OSPF MD5 Authentication (2024)

FAQs

How to Configure OSPF MD5 Authentication? ›

For MD5 authentication, you need different commands. First, use ip ospf message-digest-key X md5 to specify the key number and password. It doesn't matter which key number you choose, but it has to be the same on both ends. To enable OSPF authentication, you need to type in ip ospf authentication message-digest .

MD5 authentication provides higher security than plain text authentication. This method uses the MD5 algorithm to compute a hash value from the contents of the OSPF packet and a password (or key). This hash value is transmitted in the packet, along with a key ID and a non-decreasing sequence number.

The Open Shortest Path First (OSPF) routing protocol supports four different authentication types: Type 0: No authentication (default). Type 1: Plain-text authentication. Type 2: MD5 authentication.

For MD5 authentication, you need different commands. First, use ip ospf message-digest-key X md5 to specify the key number and password. It doesn't matter which key number you choose, but it has to be the same on both ends. To enable OSPF authentication, you need to type in ip ospf authentication message-digest .

The method md5 uses a custom less secure challenge-response mechanism. It prevents password sniffing and avoids storing passwords on the server in plain text but provides no protection if an attacker manages to steal the password hash from the server.

When OSPF adjacency is formed, a router goes through several state changes before it becomes fully adjacent with its neighbor. Those states are defined in the OSPF RFC 2328 , section 10.1. The states are Down, Attempt, Init, 2-Way, Exstart, Exchange, Loading, and Full. This document describes each state in detail.

Confirm your configuration by entering the show protocols ospf command. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration. To confirm your OSPFv3 configuration, enter the show protocols ospf3 command.

OSPF Configuration – Process ID

To enable OSPF, the top-level command at global config is 'router ospf' and then a Process ID. As you can see in the example below, I've said 'router ospf 1'. Different interfaces on a router can run in different instances or different Process IDs of OSPF.

Which two authentication methods can be used by OSPF? ›

Open Shortest Path First (OSPF) supports plain text authentication and Message Digest 5 (MD5) authentications.

Weak security: MD5 produces a fixed-sized 128-bit hash value, which is significantly shorter than modern secure hash functions like SHA-256 or SHA-3. A shorter hash length reduces the resistance against brute-force and collision attacks, increasing the risk of an attacker successfully compromising the data.

Protecting Data Between LDP Peers with MD5 Authentication

Authentication uses the Message Digest 5 (MD5) algorithm to verify the integrity of the communication and authenticate the origin of the message. To enable authentication, issue the mpls ldp neighbor command with the password keyword.

For MD5 authentication to work, both the receiving and transmitting routing devices must have the same MD5 key. In addition, a simple password and MD5 key are mutually exclusive. You can configure only one simple password, but multiple MD5 keys.

Configuring OSPF Authentication is a simple process and can be done using either clear-text passwords or MD5 authentication. Once configured, all routers in the network must use the same authentication method for communication to take place.

EAP-MD5 is the base security requirement in the EAP standard and uses username and password as the authentication credentials.

The MD5 File Validation feature allows you to check the integrity of a Cisco IOS software image by comparing its MD5 checksum value against a known MD5 checksum value for the image. MD5 values are now made available on Cisco.com for all Cisco IOS software images for comparison against local system image values.