Decoy handshake for Wireguard. Allows some initial exchange between wireguard server and client in order to derail DPI filtering.

Pre-built binaries are available here.

Run in the source directory:

make

Binary will be available in the bin directory.

Alternatively, you may invoke Go directly:

go build ./cmd/wg-decoy -o bin/wg-decoy

Add iptables rule to capture small packets targeted to wireguard port:

iptables -t mangle -A PREROUTING -i eth0 -p udp -m udp --dport 51820 -m addrtype --dst-type LOCAL -m length --length 0:44 -j TPROXY --on-port 1820 --on-ip 127.0.0.1

where instead of eth0 use actual address of your public interface, instead of port 51820 use actual wireguard server port.

Then just run server:

wg-decoy server

Make sure you use some random but fixed port in your wireguard config like this:

ListenPort = 56218

and then right before connection start run command:

wg-decoy client SERVER_ADDRESS:SERVER_PORT LOCAL_PORT

where SERVER_ADDRESS:SERVER_PORT is a WG server endpoint and LOCAL_PORT is your ListenPort value in your client config.

If you use wg-quick it may be convenient to add wg-decoy invokation as a PreUp command in your client config.

$ wg-decoy -h
Usage:

wg-decoy [OPTION]... server
wg-decoy [OPTION]... client <SERVER ADDRESS:PORT> <LOCAL WG PORT>
wg-decoy version

Options:
  -attempts uint
    	number of client request attempts (default 10)
  -bind-address string
    	server bind address (default "127.0.0.1:1820")
  -break-early
    	return as soon as minimal number of responses acquired (default true)
  -client-req string
    	client request (default "PING")
  -min-responses uint
    	minimal number of responses to collect (default 5)
  -server-resp string
    	server response (default "PONG")
  -timeout duration
    	network operation timeout (default 5s)