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Wireshark QuickStart

Tony Fortunato, Sr Network SpecialistThe Technology Firm

Troubleshooting With A VPN Client

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What are you talking about?

In some cases you need to troubleshoot through a VPN connection Some analyzers just show you encrypted ‘mumbo jumbo’ (yes it’s a real word,

look it up) You need to see the real data being transferred To complicate things, you may need to do this using a wireless connection,

which some commercial analyzers don’t natively support And of course some VPN vendors create ‘virtual adapters’ to confuse you further

In this example, I’ll use Cisco’s VPN and Microsoft’s client, since I run into them often

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What People Typically Do

The logical approach would be to capture packets from your network interface. Unfortunately many VPN clients use their own interface In the screenshot below, I pinged the default gateway with the Cisco VPN client

connected, but don’t see any evidence of it

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TIP: Launch Wireshark Quickly and Easily

The easiest way to determine which adapter to use is to select Capture->Interfaces after you VPN in and continuously ping something

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Results

Now when you capture from the correct interface you can see all you data in clear text (if the application is in clear text)

In this example my pings are clearly visible

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Microsoft interface

For the Microsoft client, I used the same methodology to determine the correct interface.

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Microsoft Client Bonus

If you select the Microsoft Client and connect, you can analyze the login process.

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Wrong Microsoft Login Credentials

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Wireshark Training - QuickStart

Tony Fortunato, Sr Network SpecialistThe Technology Firm

Thank you

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