Using Wireshark to verify encryption (sh.itjust.works)

submitted 3 months ago by Ponziani@sh.itjust.works to c/linux4noobs@programming.dev

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I am trying to use wireshark to verify that my outgoing rsync is encrypted. I can easily see that the SSH protocol packets are reported as "Encrypted packet." The other packets being exchanged are TCP packets, I am not sure how to actually verify if these are encrypted, and if not, if they contain anything sensitive.

Should TCP be encrypted? Can they leak anything when facilitating the ssh connection? How can I tell?

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[-] yggdar@lemmy.world 8 points 3 months ago

TCP is on a lower level than SSH, usually SSH uses TCP as its underlying transport layer. TCP as such is not encrypted, but it can of course be used to transport encrypted data.

Are those packages not part of the same SSH connection according to Wireshark?

[-] Ponziani@sh.itjust.works 2 points 3 months ago

It looks like everything is in 1 stream, maybe that answers your question? I am capturing traffic only on port 22 briefly while the rsync is running to look at the packets

[-] yggdar@lemmy.world 3 points 3 months ago* (last edited 3 months ago)

If the timestamps line up, maybe Wireshark just doesn't manage to understand the entire exchange. What could happen is that Wireshark sees the SSH handshake, and after that it might become just encrypted gibberish due to the encryption. In that case the SSH traffic could just show up as "some kind of TCP".

Do you see an SSH handshake, followed by random crap on the same ports?

(I'm not a Wireshark expert, just an IT guy trying to help!)

[-] Ponziani@sh.itjust.works 2 points 3 months ago

Im a little knowledgeable with this stuff but i do not know how to see the "handshake" itself, but maybe this is synonymous with what i am doing:

Right click any of the packets (TCP or SSH) > Follow > TCP stream

From there i can see some info about the ssh protocol and connection, as well as the 2 devices communicating (Operating systems used) followed by random gibberish which is the encrypted data.

When I analyze the TCP packet "frames", they contain data including the motherboard manufacturer, but packets themselves look like its just gibberish.

Thanks by the way for trying to help me :)

[-] yggdar@lemmy.world 2 points 3 months ago

Well, if

Wireshark identifies it as a single stream
Wireshark sees gibberish "TCP" and not an SSH connection
The gibberish comes after the SSH stuff that you could see (the stuff in there is going to be the handshake, my bad, that is a bit of a technical term)

Then we can be quite confident that your connection is indeed encrypted!

And of course, you're welcome!

[-] Ponziani@sh.itjust.works 2 points 3 months ago

Ok thank you!

this post was submitted on 26 Jul 2024

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