去组播（特别是ospf）

Question

I'm trying to listen for OSPFv2 Hello messages as follows:

    ens192, err := net.InterfaceByName("ens192")
    if err != nil {
            return err
    }
    c, err := net.ListenPacket("ip4:89", "0.0.0.0") // ipv4 proto 89, all local interfaces
    if err != nil {
            return err
    }
    defer c.Close()

    p := ipv4.NewPacketConn(c)
    if err != nil {
            return err
    }

    allSPFRouters := net.ParseIP("224.0.0.5")
    if err := p.JoinGroup(ens192, &net.IPAddr{IP: allSPFRouters}); err != nil {
            return err
    }

    if err := p.SetControlMessage(ipv4.FlagDst|ipv4.FlagSrc|ipv4.FlagInterface, true); err != nil {
            return err
    }

    b := make([]byte, 8192)
    for {
            n, cm, src, err := p.ReadFrom(b)
            _ = n
            if err != nil {
                    return err
            }
            if cm.Dst.IsMulticast() {
                    if cm.Dst.Equal(allSPFRouters) {
                            hdr := &ospfHeader{}
                            hdr.Decode(b)
                            fmt.Printf("%s
", hdr)
                    } else {
                            // ignore/discard
                            fmt.Printf("Received packet from: %v to %v
", src, cm.Dst)
                            continue
                    }
            } else {
                    fmt.Printf("Not mcast
")
            }
    }

but I can only see locally generated OSPF messages (ie. from OSPF process on local machine). I can't see any OSPF packets coming from remote machines (I can see them with tcpdump though). Any ideas what's wrong with the code above? Why I can only see local Hellos and not remote...?

Answer 1

Problem solved. The code is OK - the "problem" is red hat and it's firewalld...