Добрый вечер!
Случилась беда. Создал сервер на Debian9.4 на DigitalOcean, загрузил SSH ключи. При попытке зайти на сервер по ssh с MacOS возникает ошибка
ssh_exchange_identification: Connection closed by remote host
Если подключаться с другой машины под управлением Linux, то заходит без проблем.
sergey@aspmbp ~/.ssh $ ssh do2 -vvvvv
OpenSSH_7.6p1, LibreSSL 2.6.2
debug1: Reading configuration data /Users/sergey/.ssh/config
debug1: /Users/asp/.ssh/config line 4: Applying options for do2
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 48: Applying options for *
debug2: ssh_connect_direct: needpriv 0
debug1: Connecting to 46.101.181.143 port 22.
debug1: Connection established.
debug1: identity file /Users/sergey/.ssh/id_rsa type 0
debug1: key_load_public: No such file or directory
debug1: identity file /Users/sergey/.ssh/id_rsa-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_7.6
ssh_exchange_identification: Connection closed by remote host