- ssh -Q kex
- ssh -G USER@HOST G ^kexalgorithms
- ssh -v USER@HOST #debug1: kex
vim /etc/ssh/sshd_config
AllowUsers *@123.456.789.* USER@IP
KexAlgorithms sntrup761x25519-sha512@openssh.com,curve25519-sha256,curve25519-sha256@libssh.org,diffie-hellman-group14-sha256