Wondershaper—QOS in a Pinch

In past articles, I've discussed my BirdCam setup and how it automatically archives video footage from my bird feeders to YouTube every night. That's a really cool process, but unfortunately, it saturates my upstream bandwidth in the evening. I could get crafty with my firewall and limit the priority of traffic from my BirdCam server, but because it's using standard Web protocols to upload to YouTube, the firewall rules would be fairly complex. Thankfully, there's Wondershaper.

Because I'm running my BirdCam server on an independent machine, it doesn't affect any other programs on the server if I just limit the throughput on my Ethernet interface. There are three basic ways I know of to limit bandwidth on a Linux machine: using tc, trickle and Wondershaper.

The tc program is by far the most powerful. It's also by far the most complex. In fact, it's so complex that for my lazy purposes, it just isn't ideal. If you're looking for protocol-specific QOS on a local interface, tc is probably the tool for the job. It is overkill for me.

The trickle (and trickled) program seems like an ideal way to control the bandwidth on a per-application level. Supposedly, you simply can start a program with trickle, and it will limit the bandwidth available. Try as I might, however, I never could get it to do its job. Yes, I'm sure it's a perfectly wonderful tool, but again, I want something dead simple. Enter: Wondershaper.

After installing Wondershaper on your system, it works by controlling the bandwidth on an entire interface. So this:


sudo wondershaper eth0 1250 125

will limit the eth0 interface to 10mbps down and 1mbps up. The numbers are listed in KB/s (that wasn't clear to me at first, but Google will convert mbps to KB/s for you). The setting is system-wide and should limit bandwidth for any network application. To clear the limit:


sudo wondershaper clear eth0

I simply put the command in my root user's crontab to execute on startup, and my BirdCam server doesn't monopolize my bandwidth when it uploads nightly to YouTube. It seems like a simple tool, and it is. But, it works so well and provides such a useful service, I'm making Wondershaper this month's Editors' Choice winner. It's not a new program, but it's something I'd never used before, and I can't imagine living without it!

(NOTE: before I get hundreds of e-mail messages, yes, I know Wondershaper is a program from 2002. I mentioned other newer, more robust alternatives above, but the truth is, Wondershaper still is a powerful, simple tool that does one thing and does it really well.)

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Shawn Powers is a Linux Journal Associate Editor. You might find him on IRC, Twitter, or training IT pros at CBT Nuggets.