Interactive Connectivity Establishment

Defined by RFC8445.

ICE is a technique used in computer networking to find ways for two computers to talk to each other as directly as possible in peer-to-peer networking.

ICE works by exchanging multiple IP addresses and ports,which are then tested for connectivity by peer-to-peer connectivity checks

Potential candidate ip:port pairs that our peer might be able to use can be are

• IPv6 ip:ports
• IPv4 LAN ip:ports
• IPv4 WAN discovered by STUN ip:ports
• IPv4 WAN allocated by port mapping protocol ip:ports
• Operator provided endpoints (statically configured port forwards) ip:ports

This candidate list is swapped with our peer through a side channel.

Peers send probe packets against each list respectively.

Peers evaluate all candidate paths against a heuristic, selecting the best one.