CODEWITHSUNDEEP
bashshellsshexpect
barp
barp

Reputation: 6939

how to check if a host is in your known_host ssh

I have the following command works in my script that adds the host to the known hosts in ssh.

VAR2=$(expect -c '
 spawn ssh -o StrictHostKeyChecking=no '"$REMOTE_HOST_USER@$REMOTE_HOST_IP"'
 expect "*?assword:*"
 send "'"$REMOTE_HOST_PASSWD"'\r"
 expect { 
 "Permission denied, please try again." {
 exit '"$WRONG_PASSWORD"' 
 }
 }
 ')

Works fine, but I need to control before the command if the host is already in known_hosts and not execute command if it is already in known_hosts. How can i check if an host is in known_hosts?

Upvotes: 17

Views: 24742

Answers (2)

complex857
complex857

Reputation: 20753

Try: ssh-keygen -F <hostname>

Will show the known_hosts line(s) if the hostname fingerprint is found and the command returns 0, otherwise nothing is shown and the command returns 1.

Upvotes: 47

hostmaster
hostmaster

Reputation: 2170

According to ssh-keygen(1) man page

-F hostname Search for the specified hostname in a known_hosts file, listing any occurrences found. This option is useful to find hashed host names or addresses and may also be used in conjunction with the -H option to print found keys in a hashed format.

Upvotes: 4

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