Cisco IOS: Configure public RSA key authentication

Main Command: ip ssh pubkey-chain

Configuration Example in Linux:

1. Generate your key if you do not have already one: ssh-keygen

2. Split your key in 72 characters lines: fold -b -w 72 ~/.ssh/id_rsa.pub and copy output removing ssh-rsa and last part: username@hostname

3. Configure switch/router

Router_name_1#configure terminal
Router_name_1(config)#ip ssh pubkey-chain 
Router_name_1(conf-ssh-pubkey)#username YOUR_USERNAME
Router_name_1(conf-ssh-pubkey-user)#key-string
Router_name_1(conf-ssh-pubkey-data)#AAAAB6NzaC1yc2EAAAABJQAAAQEAijoMF9oBwyQxwYbVlFprz+fG8oe5uAcCxwMw       
Router_name_1(conf-ssh-pubkey-data)#eIR1lyAnDJIsYbTbcdm+n5KiQnCt2561MpN4yOFpajFNM/dqH7/jYaqaicHCSV2F       
Router_name_1(conf-ssh-pubkey-data)#RGauEp7FzN/uXxsX7mii6qOuxovl9OflLpXcvH5QH6551ycmL8nIv8UCY8uayiGI        
Router_name_1(conf-ssh-pubkey-data)#INsC0LyKEctWDW6qWp43T7rhcP0y4JoMraTCZLIPNE0Bo0bHgnGLg6fEvJmyB3sX       
Router_name_1(conf-ssh-pubkey-data)#H+7BaxHdYKg2OcIgVqYzclWhDwxj32kqd1BCq089iBMrb4QppDU2eM/t22iK29mn      
Router_name_1(conf-ssh-pubkey-data)#eqOGTiCkxB80ix+KULT9okmqkj3TbhCpunTfuPCCRNrjqndBsw==
Router_name_1(conf-ssh-pubkey-data)#exit
Router_name_1(conf-ssh-pubkey-user)#exit
Router_name_1(conf-ssh-pubkey)#exit
Router_name_1(config)#

View config:

• show ip ssh

Posible errors: %SSH: Failed to decode the Key Value. Make sure you split your key on multiple lines with fold command

Related Activities

• Cisco IOS: Associate a user with default higher privileges using username command
• transport input ssh

See also

• Configure OpenSSH to allow Public-key authentication
• ssh-keygen
• Cisco IOS: Cisco IOS XE, Config (mode), VLANs, Cisco IOS logging, VTP, ACLs, show logging, show logging history, show interface status, debug, archive, show archive, conf t, int, ip http server, ip ssh, ip address, vty, show mac address-table, show access-list, Access-list, ip access-group, admin

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Source: https://en.wikiversity.org/wiki/Cisco_IOS/Configure_public_RSA_key_authentication