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87 lines
4.2 KiB
HTML
87 lines
4.2 KiB
HTML
A few months ago we were having a lot of trouble with reliable
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internet. The problem was that we had up to three computers and three
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iPhones on the network at once, and a 1.5Mbit ADSL connection that was
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very easy to saturate if one or more of those devices was uploading or
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downloading. Additionally our ADSL router would slow and eventually stop
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working after a day or so of BitTorrent traffic flowing through it.
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So there were a few problems that needed addressing. I needed a way
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to offload the routing from the modem, get some insight into what
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was using bandwidth and ideally set up some <abbr title="Quality of
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Service">QoS</abbr> so that some bandwidth was reserved for higher
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priority traffic like HTTP and SSH.
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My chosen solution was to drop some birthday money on an [ALIX single
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board computer from PC Engines][alix]. I ordered the alix2d13 version
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along with a nice silver case for it. Its a neat little board around the
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size of two CD cases stacked on top of each other. It has a 500Mhz AMD
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Geode (x86 compatible) CPU, 256Mb RAM, USB, 3 × 10/100 Ethernet
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ports and an on-board CompactFlash socket.
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[alix]: http://www.pcengines.ch/alix2d13.htm
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TODO(Add Photos)
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Whilst waiting for the board to arrive I checked out some open source
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router targetted operating systems such as [pfSense], [m0n0wall] and
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[IPFire][ipfire]. I decided to go with m0n0wall as it was based on
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a good foundation ([FreeBSD]), happily fit on an 8Mb CF card I had lying
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around and had out of the box support for the ALIX boards.
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[pfSense]: http://www.pfsense.org/
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[m0n0wall]: http://www.pfsense.org/
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[ipfire]: http://www.ipfire.org/
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[FreeBSD]: http://www.freebsd.org/
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m0n0wall was a breeze to get up an running. I basically inserted the CF
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card, powered the board up and it was working with separate WAN and LAN
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networks, with NAT and firewall between them. It was very easy to add QoS
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through the guided traffic shaper configuration as well.
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I ran the board like this for a while and it helped with our issues but
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did not eliminate them. We still had the problem of unknown network
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activity using up all the bandwidth. The next step was to find a compact
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OS that allowed additional software to be installed. I considered
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[Alpine Linux][alpine], but settled on [OpenWRT][openwrt]. OpenWRT fit
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the bill perfectly. It was designed for embedded systems so the base
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install was very small, was designed to run from CF, has a great little
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package manager for adding an removing software, a large selection of
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packages including an optional web UI and an easy to use build system
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for building custom images and packages.
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[alpine]: http://alpinelinux.org/
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[openwrt]: https://openwrt.org/
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The recommnded installation method for OpenWRT on ALIX boards was to
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build from source so that the ALIX specific configuration and kernel
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modules can be selected. It took some time to produce an image that
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I was happy with but after that it was a simple matter of writing the
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image to a CF card and booting the ALIX board from it.
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Out of the box OpenWRT was configured for separate WAN and LAN networks
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like m0n0wall. Along with the base system I added the neat Lua based
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[LuCI][luci] web UI, support for USB mass storage devices and iftop for
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watching traffic on network interfaces.
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[iftop]: http://www.ex-parrot.com/pdw/iftop/
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[luci]: http://luci.subsignal.org/
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The addition of iftop allowed the network traffic to be examined when
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our Internet connection appeared to be be flooded. I was able to determine
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that that in some cases the problem was Wi-Fi backup to iCloud on our
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iPhones.
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There was still some instability with the ADSL though. I decided to
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swap the modem I was using for another that allowed more control
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and turned off everything except the ADSL modem functionality,
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delegating all of that to the ALIX board including maintaining the <abbr
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title="">PPPoE</abbr> connection. Since this change everything has been
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running very smoothly.
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With OpenWRT's great build and packaging system I was also able to build
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a custom package for the weather logging software that communicates with
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my [weather station][weather]. With this package installed the ALIX
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board now does the logging instead of my Mac Pro, consuming vastly less
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power in the process.
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[weather]: /personal/2010/09/weather-station/
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