HttpTunnel4vnc Logo

provides tunneling of VNC-sessions
through HTTP.

The Problem

Usually VNC-clients and -servers use a proprietary protocoll (rfb-protocoll) on user-defined ports (e.g. 5900) to communicate through a bidirectional channel. This works well as long as client and server have a direct link (no proxies or firewalls in between) or the VNC-user has full control over all components involved. But in typical real-world scenarios we have no control over firewalls (usually opening only a few well-defined ports and blocking proprietary protocolls) and we have to deal with proxies (sometimes giving the client indirect internet-access only). Therefore VNC will often not work in such real-world scenarios.

The Solution

HttpTunnel4vnc solves this problem by tunneling VNC's proprietary rfb-protocoll over HTTP. Almost all (protocol-filtering) firewalls are configured to be open for HTTP. Furthermore firewalls typically open the ports 80 and 443. In scenarios with clients placed inside a local network (often with a non-public IP) and internet-access only through HTTP-proxies, HttpTunnel4vnc will provide a working solution too.



The HttpTunnel4vnc server runs at least on GNU Linux/x86 (other java-capable plattforms are possible, but not tested).

The modified viewer works with Internet Explorer 5 (or newer) and with Mozilla using the SUN JavaPlugin (other browsers may work as well, but are not tested. Opera 6.1 is known not to work)

If you want to use multi-session support, you need Apache and it's rewrite-engine (rewrite_mod; see INSTALL in downloaded file for details).



There are 2 versions available (choose one of them):

(A) Lisp Version: forwarder 1.5

This is our production version, which is well tested.

This version requires a CMU Common Lisp environment. If you don't have CMUCL and don't want to install it: try our java version: see (B)

Download CMU Common Lisp and install it on your machine.

Download the forwarder (lisp source + binary), unpack it, and follow the instructions in the INSTALL file. The "forwarder" is the server-part of HttpTunnel4vnc.

(B) Java Version: jforwarder 0.2

This is a re-implementation in Java - not well tested but no errors known.

Download the jforwarder (java source + binary), unpack it, and follow the instructions in the INSTALL file. The "forwarder" is the server-part of HttpTunnel4vnc.


Download and compile the modified viewer (java source).

The viewer is heavily based on tightVNC 1.2.6 (see README) and has an additional required applet-parameter:

This parameter is required in all cases. The RFB protocol is tunneled on a connection to this port. The firewall (on the client side) must not block this port. Setting TUNNELPORT to -1, disables HTTP tunneling. Setting PORT to -1 forces HTTP tunneling.

  Value: TCP port number of the forwarder (server)
  Default: none.
Optional:Just is case you want to start the client from command-line (instead as an applet): Extract the sources, then change to the resulting directory "vnc_javasrc". Do the following:
1. make clean; make all
2. java VncViewer HOST "myhost" PORT -1 TUNNELPORT "4567"
(note: no "-jar .." option used)


We do not charge fees for private use, but ask you to follow the following points:


HttpTunnel4vnc is published under a
BSD-style License.

VncViewer (java client) is published under the GPL.


Helmut Eller Lead programmer: he has done most of the coding (especially all the hairy stuff) - network expert and lisp guru
Christoph Rettig Testing and programming hints - java expert and dog owner (dog's-name: "Pepe", dog-size: x-small ;-)
Martin Eller Project coordination and marketing - responsible for all the rest

The development of HttpTunnel4vnc has been sponsored by "Eller & Partner Unternehmensberatung KEG", Austria, Vienna.


last update: Jul. 2017