如何在udp端口上侦听非本地流量？

I have simple udp service in Go, but it listens only for packets generated on the local server (where my udp service is started). If packets are coming from outside , they don't reach my udp service.

func ListenUDP(syslog string) (*net.UDPConn) {
    udpAddr, _ := net.ResolveUDPAddr("udp4", syslog)        
    ln, _ := net.ListenUDP("udp", udpAddr)
    return ln    
}

func Start(conn *net.UDPConn) []byte {    
    buffer := make([]byte, 2048)
    n, _, _ := conn.ReadFromUDP(buffer)
    return (buffer[:n])
}

ln, _ := syslogd.ListenUDP("0.0.0.0:12514")
data := syslogd.Start(ln)

And I verified that packets are not blocked by local firewall or iptables