gopacket | Provides packet processing capabilities for Go

gopacket takes in packet data as a []byte and decodes it into a packet with a non-zero number of "layers". Each layer corresponds to a protocol within the bytes.

Since, there is not a lot of context here and you have not provided the base code which you have written, I can only forward you to the documentation.

So,

Reading a packet from source : https://godoc.org/github.com/google/gopacket#hdr-Reading_Packets_From_A_Source

Use layer type which you want to use while decoding :

For vxlan : https://godoc.org/github.com/google/gopacket/layers#VXLAN

You need to install the pcap development packages.

sudo apt-get install libpcap-dev

As no one responded I am going to answer it myself now.

Basically we have 3 options to handle this:

1. Create an extended TCP layer that handles our additional bytes and override default one by setting layers.LinkTypeMetadata[layers.LinkTypeTCP] to our extended version. Have a look at this example.

2. Create a new packet from the TCP payload using gopacket.NewPacket setting firstLayerDecoder to CustomLayerType and decode it normally.

3. As you mostly don't need an actual layer but instead a filled CustomLayer struct simply write a DecodeBytesToCustomStruct function where you pass TCP payload. This way we can even return multiple structs from one packets payload which wouldn't be possible otherwise.

Omit all CustomLayer code from above.

First, always check returned errors — it's your feedback:

updpLayer doesn't represent the data directly, so trying to convert it to bytes is pointless. Read the Contents or Payload field instead.

It seems I was missing libpcap-dev. Now why Go or the package didn't throw a proper error message is beyond me.

In the current version of Go, the error message is

not supported by windows

which is self-explanatory.

If you follow your call to Recvfrom(), you will find