It seems that packets sent through using gopacket/gopcap are somehow 'sent' as they are visible in a tshark trace:
444 143.613451037 127.0.0.1 → 127.0.0.1 UDP 66 6000 → 8888 Len=22
but these packets never arrive on a process on the same machine listening on 127.0.0.1:8888 (for example netcat -ul 8888).
Does anybody have any hints on why this is or things to try? As mentioned, the packets are in fact visible in a tshark trace... they just seem to completely vanish after that.
... irrelevant
out , err := pcap.OpenLive(*iface, 65535, true, -1 * time.Second)
out.WritePacketData(buf.Bytes())
... irrevelant
The idea is to construct packets and send them on lo so that a process listening on 127.0.0.1:<some port> can actually see those packets.
IP src/dst are both 127.0.0.1 and ethernet src/dst are both 00:00:00:00:00:00.
Edit:
As far as some more research goes it seems to be the case that sending packets with pcap bypasses IP network stacks in such a way that the packets can't be seen by processes. A workaround is to strip the lower levels of the packets in the trace and open a regular udp/tcp socket and send the payload through that socket.
As far as some more research goes it seems to be the case that sending packets with pcap bypasses IP network stacks in such a way that the packets can't be seen by processes. A workaround is to strip the lower levels of the packets in the trace and open a regular udp/tcp socket and send the payload through that socket.