Ciphers chacha20-poly1305@openssh.com KexAlgorithms curve25519-sha256@libssh.org MACs hmac-sha2-512-etm@openssh.com
This will shut off a lot of legacy SSH clients. Android Connectbot specifically needs the AES cipher; adding it causes problems for putty.
Otherwise, this is the classic "best practice" site for SSH:
https://stribika.github.io/2015/01/04/secure-secure-shell.ht...
Except certain version of MacOS (and Windows) ssh client would also be unable to connect.
C:\>ssh -vv me@myDJBserver.myco.com OpenSSH_for_Windows_8.1p1, LibreSSL 3.0.2 ... debug2: KEX algorithms: curve25519-sha256@libssh.org ... debug2: ciphers ctos: chacha20-poly1305@openssh.com debug2: ciphers stoc: chacha20-poly1305@openssh.com ... debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none debug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none ... $
This will shut off a lot of legacy SSH clients. Android Connectbot specifically needs the AES cipher; adding it causes problems for putty.
Otherwise, this is the classic "best practice" site for SSH:
https://stribika.github.io/2015/01/04/secure-secure-shell.ht...