See similar: Out of nowhere, ssh_exchange_identification: Connection closed by remote host Today, 6/19/12 attempting to ssh to the same host as usual ssh replied ssh_exchange_identification: Connection closed by remote host two additional attempts failed ssh -v $RWS OpenSSH_5.6p1, OpenSSL 0.9.8r 8 Feb 2011 debug1: Reading configuration data /etc/ssh_config debug1: Applying options for * debug1: Connecting to Real-World-Systems.com [174.127.119.33] port 22. debug1: Connection established. debug1: identity file /Users/dgerman/.ssh/id_rsa type 1 debug1: identity file /Users/dgerman/.ssh/id_rsa-cert type -1 debug1: identity file /Users/dgerman/.ssh/id_dsa type -1 debug1: identity file /Users/dgerman/.ssh/id_dsa-cert type -1 ssh_exchange_identification: Connection closed by remote host ping host was successful, ftp host was successful, ssh now successful, ssh -v $RWS OpenSSH_5.6p1, OpenSSL 0.9.8r 8 Feb 2011 debug1: Reading configuration data /etc/ssh_config debug1: Applying options for * debug1: Connecting to Real-World-Systems.com [174.127.119.33] port 22. debug1: Connection established. debug1: identity file /Users/dgerman/.ssh/id_rsa type 1 debug1: identity file /Users/dgerman/.ssh/id_rsa-cert type -1 debug1: identity file /Users/dgerman/.ssh/id_dsa type -1 debug1: identity file /Users/dgerman/.ssh/id_dsa-cert type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_4.3 debug1: match: OpenSSH_4.3 pat OpenSSH_4* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.6 debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: server->client aes128-ctr hmac-md5 none debug1: kex: client->server aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY debug1: Host 'real-world-systems.com' is known and matches the RSA host key. debug1: Found key in /Users/dgerman/.ssh/known_hosts:5 debug1: ssh_rsa_verify: signature correct debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey,gssapi-with-mic,password debug1: Next authentication method: publickey debug1: Offering RSA public key: /Users/dgerman/.ssh/id_rsa debug1: Authentications that can continue: publickey,gssapi-with-mic,password debug1: Trying private key: /Users/dgerman/.ssh/id_dsa debug1: Next authentication method: password ++++ What gives?? +++++++++++ Mac OS X 10.4.7 , OpenSSH_5.6p1, OpenSSL 0.9.8r 8 Feb 2011, /Users/dgerman/.ssh > ls -la total 24 drwx------ 7 dgerman staff 238 Jun 19 15:46 . drwxr-xr-x 389 dgerman staff 13226 Jun 19 15:46 .. -rw------- 1 dgerman staff 1766 Feb 26 18:25 id_rsa -rw-r--r-- 1 dgerman staff 400 Feb 26 18:25 id_rsa.pub -rw-r--r-- 1 dgerman staff 67 Feb 26 18:27 keyfingerprint -rw-r--r-- 1 dgerman staff 6215 May 1 08:11 known_hosts -rw-r--r-- 1 dgerman staff 220 Feb 26 18:26 randomart