ssh2_tunnel — Open a tunnel through a remote server
Open a socket stream to an arbitrary host/port by way of the currently connected SSH server.
An SSH connection link identifier, obtained from a call to ssh2_connect().
Example #1 Opening a tunnel to an arbitrary host
$connection = ssh2_connect('shell.example.com', 22);
ssh2_auth_pubkey_file($connection, 'username', 'id_dsa.pub', 'id_dsa');
$tunnel = ssh2_tunnel($connection, '10.0.0.101', 12345);