vncproxy
A VNC proxy that redirects to different VNC servers on different passwords

Author: Santa Zhang (santa1987@gmail.com)

This utility works as a gateway proxy to multiple VNC servers, and redirects
client connection by password to servers according to routing configuration.

The routing configuration is stored in a sqlite3 database, which should have
the following schema:

    vncproxy(forward_key varchar(8) primary key,
             dest_addr text not null,
             dest_passwd varchar(8))

The `forward_key` serves as a password to clients. When client connection
provides the correct `forward_key`, vncproxy will forward this connection
to the VNC server at `dest_addr` (host:port). If the target VNC server
requires authentication, then `dest_passwd` should be the password, otherwise
it should be null.

The sqlite3 database could be modified while vncproxy is running. Connections
will be closed if the routing configuration is deleted. For example, consider
the following situation:

  1. new record ('1', 'lab-node1:5901', 'pass123') is added to database
  2. client A is forwarded to lab-node1:5901 according to the new record
  3. record ('1', 'lab-node1:5901', 'pass123') is deleted from database
  4. client A's connection will be closed by vncproxy

This is done by periodically checking the database records, and close those
connections with invalid routing record. The checking interval is 1 second.

NOTE: If the record is modified but not deleted, then the connections will NOT
      be closed. So, if we modify the record to ('1', 'lab-node2:5901', null),
      then A's connection will NOT be closed. Modification should be done by
      first removing the record, then inserting a new version after a while.
      Since vncproxy checks record deletion every 1 second, wait a little
      longer (like 5 seconds) before insertion would be a good choice.

Currently, only RFB protocol version 3.8 is supported. And for authentication,
only the basic DES based VNC authentication is supported.

Build it by:

    ./waf configure
    ./waf

And you will find the binary at `build/vncproxy`. You can install by:

    ./waf install

The binary will be installed to `/usr/local/bin/vncproxy`.