The www6to4-1.5 HTTP proxy is a small program that is meant to act as a dual-stack front end to an IPv4 only browser. It has a few other features but those are entirely optional and not discussed here. This proxy is meant to run on a client machine and not to server a large number of clients and keep a cache for them. For the latter one is much better off with a full-fledged proxy like squid or wwwoffle.

The program is primarily distributed in source form, but binary packages for NetBSD and Debian Linux can also be found. Compilation from source normally involves no more than typing ‘make’ in the source directory. To run it, one needs a configuration file www6to4.conf including at least the following two lines:

listen-to                                  127.0.0.1,::1
listen-port                                 8000

If the www6to4.conf configuration file is located in the /etc-directory, www6to4 can simply be started with:

If the configuration file is located somewhere else its location needs to be given at the command line:

www6to4 –c <path to configuration file>/www6to4.conf

Note that there is no reason why www6to4 runs as root, it can run as an ordinary user or even as user‘nobody’.

Once www6to4 is running, all that is left to do for the user is to configure his or her web browser to use it as its the proxy (localhost:8000).

www6to4 is not an ftp proxy, it will proxy for http and https only. However, www6to4 is capable of ‘forwarding’ ftp URL’s to another proxy that does understand ftp. In that case a so-called ‘forwardfile’needs to be configured by adding the following line to the www6to4.conf file:

forwardfile <path_to>/www6to4_forward.conf

The www6to4_forward.conf should then contain a line like the following example:

ftp://* proxy.mydomain.tld:8000

The following functionality was requested and added by the 6NET project to www6to4. The program www6to4 has now a new option called “-forwardingonly”. This is useful in IPv6-only networks, where one wants to connect directly to IPv6 servers over IPv6, but where requests to IPv4 servers need to be forwarded to another (per site) dual-stack proxy. The new option provides exactly this functionality; it looks up the DNS IPv6 address records (AAAA) for the requested HTTP server and only if no such records are found will it forward the request according to the rules in the forward file (typically named /etc/www6to4_forward.conf). The forward file then needs to contain the following lines:

ftp://*                       proxy.mydomain.tld:8000
http://*                    proxy.mydomain.tld:8000

These lines tell the www6to4 program to forward any ftp or http request to proxy.mydomain.tld at port
8000.