Using Wireshark with gRPC

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Ohad

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May 18, 2021, 2:22:53 PM5/18/21
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I am trying to dissect TCP packets carrying gRPC payloads with Wireshark. Although I configured decoding as http2 and provided path to my .proto directory, Wireshark seem to only decrypt TLS data, and doesn't show the actual content.

I am using a gRPC client and server in localhost and chose the loopback interface. Also, I followed guidelines in grpc.io site: https://grpc.io/blog/wireshark/

Screenshot 2021-05-18 193309.png

Will appreciate assistance on how to properly dissect the packets and show as expected from the guide (the guide is just a reference for what I am trying to achieve here)

Sanjay Pujare

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May 20, 2021, 1:17:11 AM5/20/21
to Ohad, grpc.io
Hi,

Can you confirm that TLS was decrypted? Did you see packets like this

image.png

i.e. TLS1.2 packets with ClientHello and cert/key exchange? Also I am assuming you exported the session keys as described in https://gitlab.com/wireshark/wireshark/-/wikis/How-to-Export-TLS-Master-keys-of-gRPC .

After ensuring TLS payload was decrypted by Wireshark you can decode the payload as http2 and after that is verified you can use the .proto files to decode the protobuf payload.


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Ohad

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May 20, 2021, 4:14:05 AM5/20/21
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Seems like what I am missing is exporting the keys. Nevertheless it mentions that exporting isn't supported with the C# platforms, so I guess I can't get what I was expecting.
Thanks for your reply and helping.
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