https://www.openssh.com/
OpenSSH hardening - brute-force protection, block bots via cipher settings
ushellnotpass# tail -n 7 /etc/ssh/sshd_config KexAlgorithms curve25519-sha256@libssh.org HostKeyAlgorithms ssh-ed25519 Ciphers chacha20-poly1305@openssh.com MACs hmac-sha2-512-etm@openssh.com
If you do that, you will find some of your usual botnet friends failing during preauth.
May 3 14:33:40 ushellnotpass sshd[123]: Unable to negotiate with 58.242.83.XX port 51697: no matching key exchange method found. Their offer: diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1 [preauth]
Well then... 白白