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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

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rsync - same application version, but different protocol versions? (lemmy.ml)

submitted 20 hours ago by cyberwolfie@lemmy.ml to c/linux@lemmy.ml

15 comments fedilink hide all child comments

I have a setup that involves syncing files from my laptop to a server regularly. This has been working pretty well for a long time, apart from the odd verification failures. Both machines are WiFi-connected, so when I attempt to sync from a room far away from the WAP, the failure rates for larger files are higher, I would guess due to packet losses.

Today, I am sitting at the same spot I usually do this successfully with no issues, and I get errors after errors after errors. The odd one will go through after multiple tries, but generally it is just not working properly. I also got a broken pipe today during one attempt. This is not the first time it happens, and I feel crazy for thinking it is correlated to do bad weather, as if that should somehow affect my indoor WiFi quality...

Anyways, I tried to look at the rsync versions on the sender and receiver, and noticed that while both are the same application version number (3.2.7), they operate on different protocol versions (sender: 31, receiver: 32). I found this a bit odd, and I was unable to figure out how I would force my laptop to also use protocol version 32. I know I can pass a --protocol=NUM argument, but that seems to be used to force the sender to use an older version in case the receiver only has an older version, which is the opposite of my current situation.

And what is the likelihood that this is the cause of my woes?

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[–] cyberwolfie@lemmy.ml 3 points 18 hours ago (2 children)

Most likely something on that channel is spamming multicast. That kills most consumer wifi routers (in default settings). Usually something like a sonos or Google home broadcast group.

I might (i.e. I definitely do) have a non-ideal setup at home that contributes to this, with the router/WPA, a RPi running HA with a Zigbee antenna just next to it, my server in the shelf next over and a Sonos above it. Worst of all, the server is running on WiFi and it is sat in immediate vicinity to my router. Why? Because I could not for the life of me make the ethernet transfer speeds be more than somewhere around 1-5 MiB/s, so I gave up. But considering these issues are so infrequent from this location I assume it is mostly due to outside interference.

And adding to that, ....

Use an app like PingTools (Android) that can graph what is on each wifi channel. Check to find the cleanest channels in your area and configure your router to use that channel.

... this scan shows that all discovered networks are occupying the same channels (98-114 it looks like). I have still not figured out what OpenWRT option to go for (the OpenWRT One, which I had originally planned, quickly became very expensive with imports and tolls that I ended up not buying, despite having decided to go for it). So I am using the stock ISP router, which I assume everyone else in my building are as well. And I have been unable to locate an option to change channels in its interface.

If you’re curious and technically-minded, I highly recommend this write up: https://www.wiisfi.com/

That is a resource I didn't know I needed! Thanks :)

[–] Cyber@feddit.uk 1 points 14 hours ago

I could not for the life of me make the ethernet transfer speeds be more than somewhere around 1-5 MiB/s

That's probably a physical cable issue.

Check the connectors and / or different cables.

It's esp. more important for 1Gbps connections as they're more sensitive than 100Mbps

[–] JasonDJ@lemmy.zip 1 points 16 hours ago* (last edited 16 hours ago)

In OpenWRT, I believe it's in the settings for the "primary" ssid on each radio, which is usually the first one in the list (per radio) on the wireless settings page.

Openwrt also has options to block multicast or convert to unicast. Also make sure you are disabling lower speeds on the radio. That will reduce your max range, but devices that communicate slowly are another killer.

Broadcast and multicast both have to go at the ssid basic rate...the slowest speed supported by the AP. That could be 1Mbps. And then the AP has to repeat it. And depending on the type of traffic, this may also initiate more broadcasts from other devices on the network.

So if you can reduce broadcast/multicast, or increase the minimum speed, you'll have significantly more time. Since wireless is a shared medium, "time" is really the most critical resource.