6 ms·
Inside LAN Sync
- sahaskatta 11y agoDoes anyone know why LAN Sync is normally turned off by default?
- ComputerGuru 11y agoSecurity reasons. It can be used to confirm whether or not a certain file exists on another PC on the network by observing where it's synced to/from. That said, there's nothing novel here. People have been doing this for decades, and extensions to the bittorrent protocol use it all the time to prioritize LAN seeds over internet seeds. In fact, I believe there was talk a while back about optimizing BT to prioritize peers and seeds on the same subnet/ISP as a way of mitigating ISP bandwidth concerns and whatnot.
- sleet 11y agoFacebook use bittorrent as part of their deployment process, they exploit rack and cluster affinity to improve performance [1]. [1] https://facebook.com//download/1411324735760067/devops.pdf https://facebook.com//download/1411324735760067/devops.pdf
- toomuchtodo 11y agoROCKS clustering software was doing this before Facebook. We'd use it to reinstall Redhat on ~6000 Linux nodes. Could reinstall the entire cluster in 15 minutes while still running jobs for end users.
- gogopuppygogo 11y agoTwitter has been doing this for a while: https://blog.twitter.com/2010/murder-fast-datacenter-code-deploys-using-bittorrent https://blog.twitter.com/2010/murder-fast-datacenter-code-de...
- plorg 11y agoPerhaps your concern is slightly distinct, but the article addresses the discovery concerns you have given. Specifically, a LANSync peer can only request blocks for which it shares namespace authorization. Each distinct shared folder context (e.g. a folder shared between users, a whole Dropbox folder authorized for a single user on multiple computers) has a different namespace, and that namespace is associated with a keypair, issued by Dropbox. Block discovery and exchange is conducted over HTTPS, with each client and server having to use the key associated with the namespace of the block they wish to exchange. Since Dropbox clients/peers use SNI to identify the namespace, an eavesdropper on the network could know that two computers have access to the same namespace/folder (it is not clear from the post if the namespace contains any specific identifying information beyond its uniqueness), but not which files (or, more accurately, blocks) that namespace contained. A user who knew the key for a namespace could identify blocks being exchanged, but such a user would already have owned the Dropbox installation enough to have access not just to the list of files but to the files themselves.
- parennoob 11y agoI can say why it should be turned off by default -- because as a user, I don't want Dropbox knowing anything about computers on my network and relating IP addresses on the LAN to specific users. I'll take the long download times.
- justinsaccount 11y agoBut you are still running dropbox on those computers on your LAN. What makes you think dropbox doesn't already know all about those computers?
- teddyh 11y agoI’m disappointed that they used the stone-age method of UDP-broadcasts-on-a-reserved-port to find other servers when there are modern standards like ZeroConf which work quite well.
- zdw 11y agoUDP broadcast is probably much simpler to implement and the code to implement it is likely to be cross platform, whereas using ZeroConf would require interfacing either with the native platform's specific implementation, or including it's own implementation when the platform lacked one, and then dealing with interoperability issues between all the platforms.
- teddyh 11y agoInteroperability shouldn’t be an issue – that’s what a standardized protocol is for. MacOS X has Bonjour already built-in. On Linux you can simply require Avahi. For Windows there seems to be a large selection of available ZeroConf libraries, depending on your implementation language (unless you want to simply require Apple’s “Bonjour Print Services for Windows” bundle).
- voltagex_ 11y ago>For Windows there seems to be a large selection of available ZeroConf libraries Not the last time I looked. Apple's SDK seems to be the defacto implementation on Windows. https://learn.adafruit.com/bonjour-zeroconf-networking-for-windows-and-linux/overview https://learn.adafruit.com/bonjour-zeroconf-networking-for-w... - hah, looks like you need to get iTunes if you want the newest Bonjour. I might write something to extract it from the installer. I wonder how many EULAs I'd break in the process.
- ccccccc 11y agoYou wouldn't be the first to think of that: http://lists.apple.com/archives/bonjour-dev/2015/May/msg00006.html http://lists.apple.com/archives/bonjour-dev/2015/May/msg0000...
- sudeepj 11y agoDruva already something similar called Cloud Cache. Excerpt: Metadata is managed directly on the cloud for snapshot consistency and global deduplication across all enterprise endpoints. http://www.druva.com/documents/Druva-CloudCache-Datasheet.pdf http://www.druva.com/documents/Druva-CloudCache-Datasheet.pd...
- josho 11y agoThis explains the high cpu usage on lan sync. Using http to send large files. So, it has to constantly encode/decode to send over http. For reasons like this I'm saddened that we never standardized on a secure file transfer protocol.
- wmf 11y agoWhat do you mean by encode/decode? I would expect TLS is the bottleneck here.
- deleted 11y ago[deleted]
- deleted 11y ago[deleted]