[Erik Hjelmvik <erik.hjelmvik@xxxxxxxxx>]

Thanks for the feedback Roland!

sshdump is indeed a neat way to capture packets from a remote machine. But I'm afraid that extcap solution isn't quite what I'm looking for either. I should have explained more in detail what I'm trying to achieve, so that you folks would't have to guess. I primarily use PCAP-over-IP to read decrypted TLS packets from PolarProxy, for example as in these two examples:

* Ingesting packets from PolarProxy to Arkime: https://netresec.com/?b=20C3247

* Live extraction of TLS encrypted data in Windows: https://netresec.com/?b=221d46b

One option would be to implement an additional packet export feature to PolarProxy, which transmits decrypted packets over ERSPAN or wrapping the packets in UDP, so that they can be parsed with udpdump. However, I'm a bit reluctant to adding new features unless there is a real need for them. What I'd like to achieve in the end is for Wireshark/tshark to be able to parse decrypted traffic from PolarProxy in near-real time. Any suggestions or ideas that you might have on how we can make PolarProxy+Wireshark work better together are welcome!

PS: I actually did a live TLS decryption demo at the SEC-T conference in 2019, which was recorded and posted here:

https://www.youtube.com/watch?v=lVS0DHjgpKc

In this demo I simply pushed the decrypted PCAP stream from PolarProxy to STDOUT and piped that into Wireshark with "-i -". This integration works, but it's not how I prefer to read packets with Wireshark and it's not a viable option if PolarProxy and Wireshark are running on different machines.

/erik

Den mån 31 jan. 2022 kl 20:39 skrev Roland Knall <rknall@xxxxxxxxx>:

If udpdump is nothing for you, and you are able to run a capture tool like tshark or tcpdump on the remote machine, you can take a look at sshdump. A sibling of udpdump, it executes the remote capture program via ssh, and then transports the data as-is through a ssh-connection. It can be seen as a simple capture device on the host pc. 

Roland

Am Mo., 31. Jan. 2022 um 19:53 Uhr schrieb Erik Hjelmvik <erik.hjelmvik@xxxxxxxxx>:

Hi Dario,

Udpdump looks interesting, but I'm afraid it doesn't quite fulfill my requirements. Wrapping captured packets inside of UDP packets or IP packets (as in ERSPAN) to allow remote sniffing is an attractive solution, but it comes with several drawbacks. Some of these drawbacks include difficulties in handling captured packets that exceed the MTU between sniffer and collector, how to preserve timestamps from the original capture source etc. Transmitting packets over a TCP connection has a few drawbacks as well, but it's a method that has served me very well over the years.

As of now, I'd say that the primary drawback of using PCAP-over-IP (which really should be called  "PCAP-over-TCP") is that Wireshark/tshark can't read this data natively without having to use netcat as a shim between the TCP socket and Wireshar/tshark. I was hoping that there was an extcap solution for this, but I'm guessing I might be out of luck there :(

/erik

Den mån 31 jan. 2022 kl 14:02 skrev Dario Lombardo <lomato@xxxxxxxxx>:

You can have a look at udpdump, which doesn't use TCP but UDP, but it may fit your purpose.

On Mon, Jan 31, 2022 at 1:57 PM Erik Hjelmvik <erik.hjelmvik@xxxxxxxxx> wrote:

Hello folks,

Is there some way to read PCAP-over-IP in Wireshark? I.e. read a PCAP stream over a TCP socket.

Currently, the best solution to read PCAP-over-IP in Wireshark is by using netcat to read the PCAP stream and forward it to Wireshark's STDIN like this:

nc localhost 57012 | wireshark -k -i -

But it would be much nicer if this data could be read directly without having to use netcat. Maybe as an extcap interface?

Best regards,
Erik

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