[Ovmsdev] PCAP CAN bus dump

Mark Webb-Johnson mark at webb-johnson.net
Fri Apr 27 23:21:38 HKT 2018


PCAP support is now in (for RE).

OVMS# re start
OVMS# re serve format cap
OVMS# re serve mode simulate

# Capture over Wifi to pcap
$ nc OVMS.local 3000 >my.pcap

# Replay pcap over Wifi
$ nc OVMS.local 3000 <my.pcap >/dev/null

Seems to work ok, but I only support big endian micro-second resolution pcaps (at the moment). You’d need to fix byte ordering in the pcap header record to be able to replay your existing pcaps into it.

I’ve tested some simulated captures, into Wireshark, and it seems fine for me. Will try in a real car tomorrow. Thanks for your help with the captures. Very helpful to see what is going on with a real example.

Regards, Mark.

> On 27 Apr 2018, at 1:58 PM, Tom Parker <tom at carrott.org> wrote:
> https://carrott.org/pcaps/
> These were captured with tcpdump and an USB can interface with slcan driver. I post processed them to byte swap the can ID with https://carrott.org/git/leaf-can-dissector.git/blob/HEAD:/pcap-canid-endian-swap.py
> I don't know why tcpdump and wireshark disagree on the byte order of the can id.
> On Apr 27, 2018 5:24 PM, Mark Webb-Johnson <mark at webb-johnson.net> wrote:
>> Has anybody got an example of a PCAP format canbus dump file? Some dump from a car in a suitable format for loading into wireshark (pcap not pcapng).
>> If so, please eMail to me (mark at webb-johnson.net) or give me a link to where I can download from.
>> I need it to verify that OVMS can read/write to that format.
>> Thanks, Mark.

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