secdev / secdev/scapy

Netflow packets built by Scapy fail to decode when they contain timestamps

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Python
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Description

Brief description

I've tried generating some netflow packets and sending them to various collectors (goflow2, telegraf)

It was going alright until I tried to add flow start and end timestamps... I tried with both seconds and milliseconds. On goflow2, it just ignored the encoded timestamp and telegraf crashed.

I included the full scapy program / output / reproduction in the telegraf ticket:

influxdata/telegraf#14370

Seems like more of a scapy issue, though, considering that neither goflow2 nor telegraf could successfully decode the field.

Scapy version

2.5.0

Python version

3.9

Operating system

Rocky8

Additional environment information

No response

How to reproduce

Create packet with flowStartSeconds and send it to popular open source netflow collectors

Actual result

start seconds not decoded by collector correctly

Expected result

start seconds decoded successfully

Related resources

No response

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the full Scapy program, packet output, and reproduction linked in influxdata/telegraf#14370, focusing on packets containing the flowStartSeconds field. Compare the encoded seconds and milliseconds timestamps with how goflow2 and telegraf decode them; done means the generated NetFlow timestamps decode correctly in both collectors.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
networking
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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