i2pd

i2pd is a router for I2P, an overlay network where traffic passes through layered tunnels built across other participants' nodes instead of going straight to its destination. Services inside the network are addressed by .i2p destinations, which only a running router can resolve. i2pd is an independent implementation written in C++, offered as an alternative to the original Java router, and it usually runs as a background daemon.

The router is not a browser or a chat client in itself. It exposes an HTTP proxy and a SOCKS proxy that other programs point at in order to reach sites inside the network, plus a web console showing tunnel, peer and transport state. A tunnel configuration file maps a local port to a remote destination, or publishes a service running on your machine as a destination of its own.

Applications that speak I2P directly, such as some torrent clients, use the standard SAM and I2CP interfaces instead of the proxies. Behaviour is driven by a configuration file, so a particular setup is a matter of editing text rather than clicking through dialogs.