lots of Dup Acks, wondering if it's my capture tool

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Hello,

Here's the capture: https://www.cloudshark.org/captures/6...

I hope it's visible. This is my first cloudshark upload.

So, I got myself a Packet Squirrel from Hak5. I am using it as a capture tool.

The Packet Squirrel is a little embedded device with 2 network interfaces that runs linux. Important to note the network interfaces are fast ethernet only.

So I plug my packet squirrel between my workstation nic and the my access switch and begin capturing.

So I initiated a large ISO download from freebsd.org and captured it. The capture file above is the result of that HTTPS download (part of it).

Wondering here why I'm seeing a ton of TCP DUP ACKS. I have a funny feeling it's my capture tool, perhaps the fast ethernet interfaces are dropping packets? But I'm not sure...maybe these DUP ACKS are caused by something else?

Thanks.