ssh server cipher set

nano /etc/ssh/sshd_config
##########################
# Server sshd_config file

Ciphers aes256-gcm@openssh.com,aes256-ctr

• The server restricts which ciphers it will accept.
• The first listed cipher is preferred.

nano ~/.ssh/config
#########################
# Client ssh config file

Host remote-server
    Ciphers aes256-gcm@openssh.com,aes256-ctr

• The client requests its preferred ciphers.
• The first cipher in the list is preferred by the client.

• Both Client & Server Must Agree on a Cipher – If a cipher is not in both lists, the connection fails.
• Server Can Enforce Restrictions – If the server only allows aes256-ctr, but the client requests aes128-ctr, the client must use the server's allowed cipher.
• Client Preference Wins if Multiple Ciphers Are Allowed – If the server allows aes256-ctr,aes128-ctr and the client requests aes128-ctr first, then aes128-ctr will be used.