Tu peux voir ce qui plante en utilisant -v (minuscule, alors que pour la version c’est en majuscule).
Je te met ce que ça donne chez moi quand je forwarde sur mac-bachelard (macb en abrégé dans
brassens:fl ~:589 $ ssh -v macb
OpenSSH_6.9p1, LibreSSL 2.1.8
debug1: Reading configuration data /Users/fl/.ssh/config
debug1: /Users/fl/.ssh/config line 9: Applying options for macb
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 20: Applying options for *
debug1: /etc/ssh/ssh_config line 102: Applying options for *
debug1: permanently_drop_suid: 501
debug1: identity file /Users/fl/.ssh/id_rsa type 1
debug1: key_load_public: No such file or directory
.......
debug1: identity file /Users/fl/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.9
debug1: Remote protocol version 2.0, remote software version OpenSSH_6.9
debug1: match: OpenSSH_6.9 pat OpenSSH* compat 0x04000000
debug1: Authenticating to macb:22 as 'fl'
...................
debug1: Host 'macb' is known and matches the RSA host key.
debug1: Found key in /Users/fl/.ssh/known_hosts:11
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,keyboard-interactive
debug1: Next authentication method: publickey
..........
debug1: Authentication succeeded (publickey).
Authenticated to macb (via proxy).
debug1: channel 0: new [client-session]
debug1: Entering interactive session.
debug1: Requesting authentication agent forwarding.
debug1: Sending environment.
debug1: Sending env LANG = fr_FR
Last login: Mon Mar 26 17:30:14 2018
S’il n’y a pas assez de détails, on peut essayer jusqu’à trois v. Si ton ssh est incompatible avec celui du serveur,
-v devrait le dire.