libnice is an implementation of the IETF's draft Interactice
Connectivity Establishment standard (ICE). It provides GLib-based
library, libnice and GStreamer elements.
ICE is useful for applications that want to establish peer-to-peer
UDP data streams. It automates the process of traversing NATs and
provides security against some attacks.
Existing standards that use ICE include Session Initiation Protocol
(SIP) and XMPP Jingle.
from tom (tdmurphy4@gmail.com) with tweaks by me