Flash the Chrome EC lightbar when pf blocks a packet
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joshua stein
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README.md
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README.md
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## pflightbar
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A little utility for OpenBSD on the Chromebook Pixel to flash the lightbar red when
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pf blocks a packet.
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([Demo](https://twitter.com/jcs/status/784821967258017794))
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### Usage
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Make sure the `pflog0` device exists (usually created by `/etc/rc.d/pflogd`) and that blocked
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traffic is sent to it via a `pf` rule:
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block return log
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Then just run `pflightbar &` as root.
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It will initialize the `pcap` device, open `/dev/chromeec`, `chroot` to `/var/empty`
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and then drop privileges to `nobody`.
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`pflightbar` will load some "lightbyte" byte code into the lightbar's `program` sequence
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to flash red through a full ramp up and back down.
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This is used to minimize communication with the EC when flashing, rather than having to
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send the full RGB and dim sequences every time.
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When a blocked packet is sent to `pflog0`, `pflightbar` will see it and tell the lightbar
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to run the `program` sequence to flash red, and then return to its normal (`S0`) sequence.