Convert back message-digest-key password

[akusuma1]

Hi Expert,

We have router which already configure long time ago by someone. And for some reason, we need to change some routing configuration for this router. Since this router use "ip ospf message-digest-key md5", how to know the password that have been use before ? We plan only to change this routing on one-side only. Please help.

[Goutam Sanyal]

Hi Aku,

To enable Open Shortest Path First (OSPF) Message Digest 5 (MD5) authentication, use the ip ospf message-digest-key md5 command in interface configuration mode. To remove an old MD5 key, use the no form of this command.

#ip ospf message-digest-key key-id* encryption-type** md5 key***

#no ip ospf message-digest-key key-id*

*key-id:An identifier in the range from 1 to 255.

**encryption-type:Specifies the encryption level. The range is from 0 to 7. 0 specifies no encryption. 7 specifies a proprietary level of encryption.

***key:Alphanumeric password of up to 16 bytes.

If you know the Key-id, you can disable the status.

Hope it will help you. Thanks Goutam

[stephane.s.latulippe]

Thanks for the info, but what would be the command if you want to decrypt the MD5 encrypted password to know what the actual key is....?  I have the same issue - very old core installed by someone that has left the group and we're swapping these old 6509s for new smaller C9500s and I need to configure the OSPF message digest key on the new cores.  But to match what the provider has on his router, I need to know what's the actual decrypted key...!  

Thank you

Steph

[stephane.s.latulippe]

Would a "Copy" of the encrypted key from the old core "pasted" on the new router ospf 1 config in the new cores work...?