我有一个 CentOS 系统，可以使用多个 SSH 客户端（FireSSH、WinSCP、通过 SSH 的 MySQL Workbench）连接到该系统。由于某种原因，几天前还在运行的 PuTTY 无法连接。它将询问用户名，然后它会一直等待，直到服务器断开连接。它甚至从不要求输入密码。
关于可能出什么问题的任何想法吗？那时服务器没有发生任何变化，并且由于我可以与其他客户端连接，所以我不认为这是防火墙问题。
事件日志：
=~=~=~=~=~=~=~=~=~=~=~= PuTTY log 2015.06.23 18:08:45 =~=~=~=~=~=~=~=~=~=~=~= Event Log: Writing new session log (SSH packets mode) to file: putty.log Event Log: Looking up host "x.x.x.x" Event Log: Connecting to x.x.x.x port 22 Event Log: Server version: SSH-2.0-OpenSSH_4.3 Event Log: Using SSH protocol version 2 Event Log: We claim version: SSH-2.0-PuTTY_Release_0.63 Event Log: Doing Diffie-Hellman group exchange Event Log: Doing Diffie-Hellman key exchange with hash SHA-1 Event Log: Host key fingerprint is: Event Log: ssh-rsa 2048 xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx Event Log: Initialised AES-256 SDCTR client->server encryption Event Log: Initialised HMAC-SHA1 client->server MAC algorithm Event Log: Initialised AES-256 SDCTR server->client encryption Event Log: Initialised HMAC-SHA1 server->client MAC algorithm Event Log: Using SSPI from SECUR32.DLL Event Log: Attempting GSSAPI authentication Event Log: Server unexpectedly closed network connection