Class        Starting IPAddress    Ending IP Address    # of Hosts
A            10.0.0.0              10.255.255.255       16,777,216
B            172.16.0.0            172.31.255.255       1,048,576
C            192.168.0.0           192.168.255.255      65,536
Link-local-u 169.254.0.0           169.254.255.255      65,536
Link-local-m 224.0.0.0             224.0.0.255          256
Local        127.0.0.0             127.255.255.255      16777216

func IsPublicIP(IP net.IP) bool {
    if IP.IsLoopback() || IP.IsLinkLocalMulticast() || IP.IsLinkLocalUnicast() {
        return false
    }
    if ip4 := IP.To4(); ip4 != nil {
        switch {
        case ip4[0] == 10:
            return false
        case ip4[0] == 172 && ip4[1] >= 16 && ip4[1] <= 31:
            return false
        case ip4[0] == 192 && ip4[1] == 168:
            return false
        default:
            return true
        }
    }
    return false
}

//function to get the public ip address
func GetOutboundIP() string {
    conn, err := net.Dial("udp", "8.8.8.8:80")
    HandleError("net.Dial: ",err)
    defer conn.Close()
    localAddr := conn.LocalAddr().String()
    idx := strings.LastIndex(localAddr, ":")
    return localAddr[0:idx]
}