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Cisco IOS/Configure public RSA key authentication

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Main Command: ip ssh pubkey-chain[1]

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:

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

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See also

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  1. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/sec_usr_ssh/configuration/15-s/sec-usr-ssh-15-s-book/sec-secure-shell-v2.html