Matching Key Pair for Both Client and Server.
Different Keys are Public & Private.
ssh-keygen produce public and private key.
SSH connectivity is used for
1)Tunneling (or)Forwarding TCP Ports,
2)X11 connection. Forwarding X from a Remote host.
3)login into remote house( replacing telnet and rlogin)
When we were going to connect from the client to server via ssh Background Activities
2)then connecting to the specified port For Example - 22.
3)then it'll check remote protocol and remote protocol software version for openssh.
4)if it match any one of the protocol For then enable compatibility mode for protocol.
5)it will check Remote-IP is know & matches with RSA Key fingerprint ,/etc/.ssh/known_hosts , if it is matches then go further. or ask for confirmation.
6)then it will move to the authentication method.
public key with following files /root/.ssh/identity
public key /root/.ssh/id_rsa
trying private key /root/.ssh/id_rsa
or else finally ask for Next authentication method : password
authentication will be succeed by public key
debug1: Authentication succeeded (public key).
debug1: Authentication succeeded (password).
7)if authentication is correct.
8)create the client channel session
9)setting the environment.