Skip to content

Latest commit

 

History

History
122 lines (87 loc) · 4.37 KB

README.md

File metadata and controls

122 lines (87 loc) · 4.37 KB

kcptun-libev

A lightweight alternative implementation to kcptun

What's this?

kcptun-libev is a TCP port forwarder which converts the actual transferring protocol into a UDP based one, called KCP. KCP is more configurable and usually has a much better performance in a lossy network. This project can help you to get better bandwidth in such situation.

For example, wrap your server to use KCP instead of TCP:

client -> kcptun-libev client -> lossy network(KCP) -> kcptun-libev server -> server

Or typically, the people who using a lossy network may setup kcptun-libev with a proxy server. To get the internet access speeded up.

network access -> proxy client -> kcptun-libev client -> lossy network(KCP) -> kcptun-libev server -> proxy server -> stable network

Read more about KCP

Features

  • Secure: For proper integration of the cryptography methods.
  • Fast: No muxer, one TCP connection to one KCP connection with 0 RTT connection open.
  • Proper: KCP will be updated on demand, no unnecessary lag introduced.
  • Simple: Without FEC craps.
  • Morden: Full IPv6 support.
  • Dynamic IP aware: Dynamic IP address and UDP hole punching are supported.
  • Configurable: Encryption can be completely disabled or even excluded from build
  • Compatible: Compliant with ISO C standard.

There is a previous implementation of kcptun which is written in Go.

Compared to that, kcptun-libev should be much more lightweight. The main executable is around 100KiB on most platforms* and it also have a much lower cpu/mem usage.

* Some required libraries are dynamically linked, see runtime dependencies below.

Security

kcptun-libev can optionally encrypt KCP packets with a password/preshared key. With encryption enabled, the integrity and privacy is guaranteed. It uses the libsodium implementation of chacha20poly1305-ietf, which is an AEAD method.

If the encryption is not enabled or not even compiled, no packet overhead is consumed.

In practice, I strongly suggest user to use "--genpsk" command-line argument to generate a strong random preshared key instead of using a simple password.

Compatibility

System

Theoretically all systems that support ISO C11.

Name Level Notes
Ubuntu developed
OpenWRT tested
Unix-like theoretical supported
Cygwin/MinGW theoretical supported

Protocol

kcptun-libev do NOT provide compatibility to any other KCP implements.

The major version number is the protocol version. Different protocol versions are not compatible.

Build

Dependencies

Name Kind Related Feature
libev required
libsodium optional Connection encrypting 
# Debian & Ubuntu
sudo apt install -y libev-dev libsodium-dev

Build on UNIX-like systems

mkdir build && cd build
cmake -DCMAKE_BUILD_TYPE="Release" ..
make -j$(nproc --all)

See m.sh for more information about cross compiling support.

Runtime

Dependencies

# Debian & Ubuntu
sudo apt install -y libev4 libsodium23
# OpenWRT
opkg install libev libsodium

Usage

Create a config file and pass the file name. Just like:

./kcptun-libev -c server.json

See server.json/peer.json in the source repo for your reference.

Let's explain some fields in server.json/peer.json:

  • The client side "listen" TCP ports and send data to "udp_connect".
  • The server side receive data from "udp_bind" and forward the connections to "connect".
  • Set a password is strongly suggested when using in public networks.
  • Log level: 0-6, the default is 2 (INFO)

Credits

Thanks to: