Typical scenario: I'm trying to SSH thru a corporate HTTP proxy to a remote machine using corkscrew, and I get: ssh_exchange_identification: Connection closed by remote host Obviously, there's a lot of reasons this might be happening - the proxy might not allow this, the remote box might not be running sshd, etc. So, I tried to tunnel manually via telnet: $ telnet proxy.evilcorporation.com 82 Trying XX.XX.XX.XX... Connected to proxy.evilcorporation.com. Escape character is '^]'. CONNECT myremotehost.com:22 HTTP/1.1 HTTP/1.1 200 Connection established So, unless I'm mistaken... it looks like the connection is working. So, why then, doesn't it work via corkscrew? ssh -vvv [email protected] -p 22 -o "ProxyCommand corkscrew proxy.evilcorporation.com 82 myremotehost.com 22" OpenSSH_6.6, OpenSSL 1.0.1f 6 Jan 2014 debug1: Reading configuration data /etc/ssh/ssh_config debug1: /etc/ssh/ssh_config line 19: Applying options for * debug1: Executing proxy command: exec corkscrew proxy.evilcorporation.com 82 myremotehost.com 22 debug1: permanently_set_uid: 0/0 debug1: permanently_drop_suid: 0 debug1: identity file /root/.ssh/id_rsa type -1 debug1: identity file /root/.ssh/id_rsa-cert type -1 debug1: identity file /root/.ssh/id_dsa type -1 debug1: identity file /root/.ssh/id_dsa-cert type -1 debug1: identity file /root/.ssh/id_ecdsa type -1 debug1: identity file /root/.ssh/id_ecdsa-cert type -1 debug1: identity file /root/.ssh/id_ed25519 type -1 debug1: identity file /root/.ssh/id_ed25519-cert type -1 debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_6.6p1 Ubuntu-2ubuntu1 ssh_exchange_identification: Connection closed by remote host