We wish to block all UDP fragments from entering our network.

[hanky]

We wish to block all UDP fragments from entering our network.  Dropbox LAN sync uses UDP port 17500 for discovery but I need to know the IP address that Dropbox is using so I can add it to an exception list to allow UDP fragments through.

[Rich]

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@hanky wrote:

... I need to know the IP address that Dropbox is using so I can add it to an exception list to allow UDP fragments through.

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I doubt they'll publish that information here, and I doubt it's a single IP address anyway. You can find a list of the official domains that Dropbox uses here, and you can find other information on the IP ranges that Dropbox uses with a search of the net.

Your best option, however, would be to analyze the traffic on your own network to determine what IP ranges your clients are connecting to.

[Здравко · Accepted solution]

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@hanky wrote:

We wish to block all UDP fragments from entering our network.  ... but I need to know the IP address that Dropbox is using so I can add it to an exception list to allow UDP fragments through.

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Hi @hanky,

There is no need to handle in any special way Dropbox UDP packets. 🙂 You may block all of them since they never get in or out of your LAN (that's why LAN Sync); just don't prevent them to flow locally. The IP address in use is the same any other discovery service uses - your local broadcast address. 😉 That's it.

Hope this helps.

PS: local broadcast address: Let's say your machine IP address is 192.168.0.10/24 (e.g. IP mask 255.255.255.0). In such a case your discovery/broadcast IP address is 192.168.0.255 if you need it at all. Simple, right?! 😜