TCP "Standard" Tunnels:

TCP Tunnels provide a transparent bridge between TCP applications and I2P networks. These "Standard" tunnels enable secure, anonymous communication by creating direct connections between TCP endpoints and I2P destinations.

TCP Server Tunnel

A TCP Server tunnel connects a local TCP service to the I2P network through:

A TCP Client component that interfaces with the local service
An I2P Service component that maintains a persistent destination address

When an I2P peer connects to the tunnel's destination, the traffic flows:

Incoming: I2P Network → I2P Service → TCP Client → Local Service
Outgoing: Local Service → TCP Client → I2P Service → I2P Network

TCP Client Tunnel

A TCP Client tunnel operates by:

Running a TCP Server that listens on a local port
Maintaining an I2P Client connected to a specific destination

When activated:

Local applications connect to the TCP Server
Traffic routes through the I2P Client to the target I2P destination
Creates a secure point-to-point connection

Both tunnel types preserve the original TCP traffic while adding I2P's anonymity and encryption layers.

When a local client connects to the I2P tunnel's destination, the traffic flows:

Outgoing: Local Client → TCP Server → I2P Client → I2P Network
Incoming: I2P Network → I2P Client → TCP Server → Local Client