A reverse proxy, focused on connecting IPv4-only servers with IPv6 clients.
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This is very very experimental. 
Send the feedback on your experiments to ayourtch at gmail.

SXxis: 6-access if viewed from the server side.

This small program serves one purpose: help the IPv4 servers and
IPv6 clients meet.

It does so by terminating the connections from the IPv6 clients,
getting a little bit of data from them, figuring out which IPv4
host to contact, and then connecting the  IPv4 and IPv6 worlds. 

Currently it supports only HTTP, but in principle HTTPS is also
possible - for the clients that do include the hostname into 
the SSL Client Hello record.

In HTTP, the sxxis scans the beginning of the request for 
the "Host: " header, and retrieves the hostname from this header.
Then it derives the "target hostname" and does an A lookup for it.

The resulting IPv4 address is used to connect to the server. 
When the connection is established, the IPv4 and IPv6 sides 
are shortcut, and the data is sent between them.

The derivation of the "target hostname" involves 
appending the REAL_TARGET_PREFIX macro value to 
the "Host:" header from the HTTP request.

A word of warning:

Since it is only in the first request that 
the remote IP is included, this is a security risk.


You need the udns and libev installed in order to compile it.

On Ubuntu/Debian, this means:

sudo apt-get install libudns-dev libev-dev


UDNS library:

Porting applications to IPv6 HowTo: