This tutorial takes a thorough look at using MindTerm, a Java
program that allows for encrypted tunneling via SSH as either a
standalone program or as a browser-based applet. At its simplest
level, MindTerm makes for a handy way to get a secure login to a
machine running ssh from any browser. On a more complex level, it
provides a way to access a host of services in a more secure manner
than usual.
“SSH and MindTerm will work together to use a technique
called port forwarding. Port forwarding is forwarding traffic from
one host and a given port to another host and port. In other words,
the MindTerm application will open a port on the client’s machine
(local machine) and any connection to that local port is forwarded
to the remote host and its listening port over an encrypted ssh
session. Whether or not the connection is accepted depends on the
type of request you are sending to the remote host. For example,
you wouldn’t forward POP requests to a remote host listening on
port 21 because port 21 is reserved for ftp requests. Port
forwarding is also used to allow connections to a server that is
behind a firewall and/or has a private IP address. Essentially this
is creating a Virtual Private Network (VPN). A VPN is “a private
data network that makes use of the public telecommunication
infrastructure, maintaining privacy through the use of a tunneling
protocol and security procedures” (www.whatis.com). The
port-forwarding can only be done with TCP services.”