Looking for a good multiple protocol proxy!!

[Neal Hamilton]

I am looking for a proxy server  that has the following features.

1. multiple protocols    .... http/s,  socks 4/5, ftp, irc, nntp, smtp, 
etc...   The ability to add plugins to support more protocols . You know 
what i mean,, may not be through protocols but somehow the ability to 
support more protocols if needed.

2. Authentication .....  Preferably i would like the proxy to be able to 
use my Openldap for authentication,, or maybe a radius ....but i must 
have authentication as i dont want some to have access at all and others 
access to certain protocols only.

3. scalable, fast

4. Opensrc.. :)

Thanks and have a great day.