ShadowSocks is a free and open-source encrypted proxy project, widely used in mainland China to circumvent Internet censorship. It was created in 2012 by a Chinese programmer named "clowwindy", and multiple implementations of the protocol have been made available since. Typically, the client software will open a socks5 proxy on the machine it is running, which internet traffic can then be directed towards, similarly to an SSH tunnel. Unlike an SSH tunnel, shadowsocks can also proxy UDP traffic.