package net import "net" func GetFreeTcpPort() (int, error) { addr, err := net.ResolveTCPAddr("tcp", "localhost:0") if err != nil { return 0, err } l, err := net.ListenTCP("tcp", addr) if err != nil { return 0, err } defer l.Close() return l.Addr().(*net.TCPAddr).Port, nil }