How Does Dropbox Lan Sync Work?

I have installed Dropbox on 2 Ubuntu machines and enabled LAN sync. I was curious how does one Dropbox instance detect another.

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It looks like a UDP broadcast packet is sent over the LAN.

I found these links to support:

"we've experimented with various service discovery protocols, both standardized and our own. right now we're using UDP broadcast, but we're testing a few different ideas to see what'll work best for most people. the server is only involved in lansync negotiation to enforce our security model."

For example, if I look at a packet capture for my LAN I see "[source IP] 255.255.255.255 DB-LSP-Dropbox LAN Sync Discovery Protocol" every few seconds.

It does by sending UDP packets every 30 seconds. Check the post below ...

Dropbox LAN Sync Protocol (archived)

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Sarah Jenkins

Sarah Jenkins

Senior Technology Editor & AI Specialist

Sarah Jenkins is a veteran tech journalist with over 12 years of experience covering artificial intelligence, mobile innovations, and digital ethics. Her insights have appeared in leading technology publications worldwide.

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