This code snippet demonstrate the tcp simultaneous connection feature. No one of the goroutines has a listening socket, yet, when both try to connect to each other simultaneously the connection succeeds. I've yet to understand what is this feature good for, I definitely know what is it not good for: http://golang.org/src/pkg/net/tcpsock_posix.go…

tcpsymcon.go

package main

import "fmt"
import "net"

var localhost = net.ParseIP("127.0.0.1")

var port1, port2 = 1220, 1229
func conwrite() {
  c1, err := net.DialTCP("tcp", &net.TCPAddr{localhost, port2}, &net.TCPAddr{localhost, port1})
	if err != nil {
		panic(err)
	}
	c1.Write([]byte("hoho"))
}
func conread() {
	buf := make([]byte, 100)
	c1, err := net.DialTCP("tcp", &net.TCPAddr{localhost, port1}, &net.TCPAddr{localhost, port2})
	if err != nil {
		panic(err)
	}
	nr, err := c1.Read(buf)
	if err != nil {
		panic(err)
	}
	fmt.Println("Got", string(buf[:nr]))
}

func main() {
	go conwrite()
	conread()
}