I just figured this out. I need to manually set the NIC to promiscuous
mode.
Now the question is, is there a way to set the NIC to promiscuous mode in
code, like in pcap.openlive?? I don't see that option with AF_packet.
Thanks,
Chun
On Tuesday, October 17, 2017 at 6:31:21 PM UTC-4, Chun Zhang wrote:
>
> Hi, friends,
>
> I am trying to create a very simple network sniffer. Initially I
> implemented it with libpcap, but I got not only performance issue, but also
> timing issue. Now I am trying to replace libpcap with afpacket. However, I
> am not able to get any packet from the GRE tunneled terminated at the
> listening NIC.
>
> I know I have quite a few packets terminated at this NIC. If using pcap as
> below, then I see all those packets, decoded up to the GRE layer, and its
> payload.
> But switching to afpacket, I can only get non-GRE packet, such as IGMP,
> ICMP, etc. (These packets are also seen in the above pcap version). I can
> see normal TCP packets as well, but no GRE packets, they are not even read
> from wire as far as I can see, since there is no decoding error at all.
>
> So, my dear gophers, what have I done wrong? Any help is appreciated. I
> have googled quite a bit, but does not really get any useful answer.
> Do I need to somehow magically enable the promiscuous mode? I don't see an
> option in afpacket.
>
>
> Here is my code snippet
>
>
> //pcap version
> handle, err = pcap.OpenLive(device, snapshot_len, promiscuous, timeout)
> if err == nil {
> Info.Println("Open interface ", device, "successfully")
> }
> defer handle.Close()
>
>
>
> //afpacket version
> handle, err := afpacket.NewTPacket(afpacket.OptInterface(device))
>
> if err != nil {
> Error.Printf("Error opening afpacket interface: %s", err)
> }
>
> defer handle.Close()
>
>
> //create a source and listen to it
>
> packetSource := gopacket.NewPacketSource(handle, layers.LinkTypeEthernet)
>
>
> for {
>
> packet, err := packetSource.NextPacket()
> // Iterate over all layers, printing out each layer type
> for _, layer := range packet.Layers() {
> fmt.Println("PACKET LAYER:", layer.LayerType())
> }
>
>
>
> Here is my code snippet,
>
>
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