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Set afpacket socket in promiscuous mode #564

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dawei73 opened this issue Nov 20, 2018 · 2 comments · May be fixed by #1166
Open

Set afpacket socket in promiscuous mode #564

dawei73 opened this issue Nov 20, 2018 · 2 comments · May be fixed by #1166

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@dawei73
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dawei73 commented Nov 20, 2018

It would be nice to be able to set the socket in promiscuous mode.

perhaps something like this:

func (h *TPacket) SetPromiscMode(ifaceName string) error {
	ifIndex := 0
	// An empty string here means to listen to all interfaces
	if ifaceName != "" {
		iface, err := net.InterfaceByName(ifaceName)
		if err != nil {
			return fmt.Errorf("InterfaceByName: %v", err)
		}
		ifIndex = iface.Index
	}
	var sp C.struct_packet_mreq
	sp.mr_ifindex = C.int(ifIndex)
	sp.mr_type = unix.PACKET_MR_PROMISC
	sp.mr_alen = 0
	sp.mr_address = [8]C.uchar{0,0,0,0,0,0,0,0}
	if err := setsockopt(h.fd, unix.SOL_PACKET, unix.PACKET_ADD_MEMBERSHIP, unsafe.Pointer(&sp), unsafe.Sizeof(sp)); err != nil {
		return fmt.Errorf("setsockopt promisc mode: %v", err)
  }
	return nil
}
@norg
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norg commented Feb 11, 2020 •
edited
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This would be very helpful as it could help in some scenarios where we don't see any packets unless it's set to promiscuous mode. Is there any plan to include this?

Current workaround is ip link set $INTERFACE promisc on.

@maxatome
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maxatome commented Apr 26, 2024 •
edited
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Using reflect, so very dirty :)

func setPromiscuous(tp *afpacket.TPacket, ifidx int, on bool) error {
	mreq := unix.PacketMreq{
		Ifindex: int32(ifidx),
		Type:    unix.PACKET_MR_PROMISC,
	}
	opt := unix.PACKET_DROP_MEMBERSHIP
	if on {
		opt = unix.PACKET_ADD_MEMBERSHIP
	}
	fd := int(reflect.ValueOf(tp).Elem().FieldByName("fd").Int())
	return unix.SetsockoptPacketMreq(fd, unix.SOL_PACKET, opt, &mreq)
}

ifidx is the interface index.

maxatome added a commit to maxatome/gopacket that referenced this issue Apr 26, 2024
@maxatome
Add (*afpacket.TPacket).SetPromiscuous
35c1a1f 
Closes google#564.

Signed-off-by: Maxime Soulé <[email protected]>
@maxatome maxatome linked a pull request Apr 26, 2024 that will close this issue
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Add (*afpacket.TPacket).SetPromiscuous maxatome/gopacket
3 participants
@norg @maxatome @dawei73