将 PTPv2 层添加到 scapy

Question

I want to add a PTPv2 Layer to scapy (v2.3.3) in python (v2.7). I added the ptpv2 class with the PTP entries to the file /scapy/layers/inet.py (because PTP is at layer 4). I also bound the ptpv2 layer to the upper layer, in my case Ethernet.

bind_layers(Ethernet,ptpv2)

By typing the scapy command "ls()" the created ptpv2 layer is listed, ok, success. But by accessing the layer through the python commands

for packet in PcapReader('/media/sf_SharedFolder/test.pcap'):
  if packet[ptpv2].sequenceId == anything:
    # do sth

the following error occurs:

File "/usr/lib/python2.7/dist-packages/scapy/packet.py", line 817, in __getitem__
  raise IndexError("Layer [%s] not found" % lname)
IndexError: Layer [ptpv2] not found

The Wireshark file has the layers Frame -> Ethernet -> PTP, so my binding command has to be right.

Don't know where the error is.

Pls, help me!

Thx

Chris

Answer 1

Your dissector is probably failing, but Scapy hides that and decodes the layer as Raw() .

You can:

• check that by checking that packet.payload is a Raw instance.
• try to find what crashes in your dissector by setting conf.debug_dissector = True .