pip3 install -r requirements.txt
sudo python3 setup.py install
This python module contains the layer definition for PTPv2 (GPTP) which includes custom
definitions for Timestamp
and ClockIdentity
fields. It further provide some handy utils when
analyzing PTPv2 traces.
The PTPv2
layer is automatically bound to the Ethernet layer based on its type
field (0x88F7
).
Just import the PTPv2
layer definition to make scapy aware of this bond and for example read a
pcap file to dissect
from gptp.layers import PTPv2
from scapy.utils import rdpcap
pcap = rdpcap("traces.pcap")
for p in pcap:
if p.haslayer('PTPv2'):
p.show()
which yields something like
###[ Ethernet ]###
dst = 01:83:b0:02:21:fe
src = 7a:1b:31:80:11:06
type = 0x88f7
###[ PTPv2 ]###
transportSpecific= 1
messageType= Sync
reserved0 = 0x0
versionPTP= 2
messageLength= 44
domainNumber= 0
reserved1 = 0x0
flags = TIMESCALE+TWO_STEP
correctionField= 0
reserved2 = 0x0
sourcePortIdentity= 7a:1b:31:80:11:06:01:00:0002
sequenceId= 2081
control = 0x0
logMessageInterval= -3
reserved3 = None
###[ Padding ]###
load = '\x00\x00\x00\x00\x00\x00'
A handy addition when analyzing PTP traces is the MatchedList
from utils
module. You can add PTP
packets to it and it will automatically find matching (Sync, FollowUp)
message pairs as well as
(PdelayReq, PdelayResp, PdelayRespFollowUp)
message triplets, providing them as lists for easy
processing and analysis.
from gptp.utils import MatchedList
pcap = rdpcap("traces.pcap")
matched_list = MatchedList([p for p in pcap if p.haslayer('PTPv2')])
(sync, fup) = matched_list.sync[0]
assert sync.sequenceId == fup.sequenceId
print(fup.preciseOriginTimestamp) # prints 1602135835.0758622