Configure RIP Plain Text authentication on an interface to enable authentication for RIP Version 2 packets .

This task enables RIP authentication on interfaces to secure RIP Version 2 packet exchanges and prevent unauthorized routing updates.

RIP Version 1 does not support authentication. If you are sending and receiving RIP Version 2 packets, you can enable RIP authentication on an interface.

The key chain specifies the set of keys that can be used on the interface. If a key chain is not configured, the interface does not perform authentication, including the default option.

How to Configure RIPv2 Authentication with a Key Chain

Create the Key Chain and Keys:
Define a key chain and configure the key ID and password (key-string):

text

Device(config)# key chain <key-chain-name>
Device(config-keychain)# key <key-id>
Device(config-keychain-key)# key-string <password>

Apply Authentication to the Interface:

Device(config-if)#ip rip authentication key-chain <chain name>
device(config-if)#ip rip authentication mode text

Configuration on Router R1:

R1(config)#router rip
R1(config-router)#version 2
R1(config-router)#network 1.0.0.0
R1(config-router)#exit
R1(config)#key chain satish
R1(config-keychain)#key 1
R1(config-keychain-key)#key-string tiwary
R1(config-keychain-key)#exit
R1(config-keychain)#exit
R1(config)#int fa0/0
R1(config-if)#ip rip authentication key-chain satish
R1(config-if)#ip rip authentication mode text

Configuration on Router R2:

R2(config)#router rip
R2(config-router)#version 2
R2(config-router)#network 1.0.0.0
R2(config-router)#exit
R2(config)#key chain satish
R2(config-keychain)#key 1
R2(config-keychain-key)#key-string tiwary
R2(config-keychain-key)#exit
R2(config-keychain)#int fa0/0
R2(config-if)#ip rip authentication key-chain satish
R2(config-if)#ip rip authentication mode text
R2(config-if)#

Important Rules

• RIPv1 Limit: RIPv1 does not support authentication; it must be running RIPv2.
• Matching Parameters: Neighboring routers must share the exact same key-string and authentication mode. For MD5 mode, the key number (ID) must also match between neighbors.
• Verification: Use commands like
• show ip rip
• show keychain
• debug ip rip
• to check status and troubleshoot failed handshakes