25C3 -

25th Chaos Communication Congress
Nothing to hide

Daniel Haslinger
Bernhard Fischer
Day Day 3 (2008-12-29)
Room Saal 2
Start time 18:30
Duration 01:00
ID 2828
Event type lecture
Track Hacking
Language used for presentation en

OnionCat – A Tor-based Anonymous VPN

Building an anonymous Internet within the Internet

OnionCat manages to build a complete IP transparent VPN based on Tor's hidden services, provides a simple well-known interface and has the potential to create an anonymous global network which could evolve to a feature- and information-rich network like we know the plain Internet today.

Tor provides so-called "Hidden Services". These are services which are location hidden within the Tor network. This means that not only users are hidden but also services (destination). Tor manages this by assigning virtual addresses to them, so-called .onion-URLs. Tor builds all connections based on them.

Unfortunately, access to hidden services is currently not very user-friendly which makes them unattractive although they could provide high privacy in today's world.

OnionCat provides an IP-transparent service which does on-demand connections to designated hidden services. This is a Tor-specific virtual private network (VPN). Because of its IP-transparency any client program can use hidden services without further workarounds.

This talk is about OnionCat in general, gives a brief introduction into its internals and application examples.