* Location Logging
This document was created by Steven Baltakatei Sandoval on
-<2020-06-29 Mon 12:14> under a [[https://creativecommons.org/licenses/by-sa/4.0/][Creative Commons BY-SA 4.0 license]]. It
-was updated by Steven Baltakatei Sandoval on <2020-06-29 Mon 16:05>.
+~2020-06-29T12:14Z~ under a [[https://creativecommons.org/licenses/by-sa/4.0/][Creative Commons BY-SA 4.0 license]]. It
+was updated by Steven Baltakatei Sandoval on ~2020-07-12T21:04Z~
+#+TITLE: Ninfacyzga-01 Manual
+#+AUTHOR: Steven Baltakatei Sandoval
+#+EMAIL: baltakatei@gmail.com
** Narrative
Ninfacyzga-01 records (logs) its position in time and space using a
[[https://en.wikipedia.org/wiki/Satellite_navigation_device][GPS receiver]]. The NMEA location data produced by the receiver is
**** PiZ UpTime 2.0
See the [[https://alchemy-power.com/piz-uptime-2-0/][OEM]] webpage for this product.
*** Software
-~bkgpslog~ : The bash script that performs the location data
-collection and processing. Is an executable file contained within this
-repository at ~exec/bkgpslog~. It should be copied to
-~$HOME/.local/bin~.
+~bklog~ : A bash script that saves its stdin stream to a tar file. The
+file may be compressed by ~gzip~ and encrypted by ~age~. It is an
+executable file contained within this repository at ~exec/bklog~. It
+should be copied to ~$HOME/.local/bin~.
+
+~bkgpslog~ : A legacy bash script similar to ~bklog~ but narrower in
+scope in that it only records output from ~gpspipe~.
~gpsd~ : A background daemon app capable of interfacing with the
Ozzmaker BerryGPS-IMU's GPS submodule. Installed and initialized by
~apt~.
~gpsbabel~ : A command line app that converts GPS data from one format
-into another. ~bkgpslog~ uses it to convert NMEA data into GPX and
+into another. ~bklog~ may be used to convert NMEA data into GPX and
KML. Installed via ~apt~.
~gzip~ : A simple command line app that compresses stdin into a
should be copied to ~$HOME/.local/bin~.
**** Narrative
-~bkgpslog~ populates a 60-second buffer with NMEA data from ~gpsd~ via
-~gpspipe~. This buffer is used by ~gpsbabel~ to produce GPX and KML
-versions of the buffer. All 3 buffers are then comprssed with ~gzip~,
-encrypted with ~age~, and then written to disk.
+~bklog~ may be used to log location data by receiving stdout produced
+by ~gpspipe~. ~bklog~ contains options that allow file writes to be
+performed at adjustable time intervals (default: 300 seconds),
+compressed (with ~gzip~), and encrypted (with ~age~). Files are
+written in the form of appendages to a ~tar~ archive saved to a
+specified location. The NMEA data produced by ~gpspipe~ may be
+processed via a ~gpsbabel~ command string specified as an option to
+~bklog~, assuming ~gpsbabel~ is installed.
*** Output
+
+Several output file formats have been tested with ~bklog~.
+
**** File Formats
***** NMEA
-See the [[https://en.wikipedia.org/wiki/NMEA_0183][Wikipedia page]] for this.
+See the [[https://en.wikipedia.org/wiki/NMEA_0183][Wikipedia page]] for this. This file format is the default
+output of the ~gpspipe -r~ command.
***** GPX
-See the [[https://en.wikipedia.org/wiki/GPS_Exchange_Format][Wikipedia page]] for this.
+See the [[https://en.wikipedia.org/wiki/GPS_Exchange_Format][Wikipedia page]] for this. [[http://wiki.gis.com/wiki/index.php/WGS84][WGS84]] is the datum used. An NMEA file
+may be converted to this format using ~gpsbabel~.
***** KML
-See the [[https://en.wikipedia.org/wiki/Keyhole_Markup_Language][Wikipedia page]] for this.
+See the [[https://en.wikipedia.org/wiki/Keyhole_Markup_Language][Wikipedia page]] for this. [[http://wiki.gis.com/wiki/index.php/WGS84][WGS84]] is the datum used. An NMEA file
+may be converted to this format using ~gpsbabel~.
+
**** Encryption Method
Files produced by the bkgpslog script are encrypted against a set of
-public keys using [[https://github.com/FiloSottile/age][age]]. The public keys are bech32 strings supplied as
-options to bkgpslog when called.
+public keys using [[https://github.com/FiloSottile/age][~age~]], a simple command line encryption tool
+selected over ~gpg~ because of ~age~'s deliberate lack of
+configurability.
+
+The public keys are bech32 strings supplied as options to bkgpslog
+when called. The secret key should *NOT* be stored in Ninfacyzga-01.
+
+If a key pair was generated using ~age-keygen~, then it is an [[https://en.wikipedia.org/wiki/Curve25519][~X25519~]]
+key pair. See the [[https://age-encryption.org/v1][~age~ Version 1 specification]].
+
+An ~ssh-rsa~ or ~ssh-ed25519~ SSH public key string may be used instead of
+the bech32 public key string produced by ~age-keygen~ for convenience.
+
+Help information for ~age~ is available by running ~$ age --help~.
+***** Encryption Commands
+****** Encryption through ~age~
+In order to illustrate how ~bklog~ encrypts files, below is an example
+command illustrating how ~age~ may be used to encrypt a file.
+
+#+BEGIN_EXAMPLE
+$ echo "asdf" | age -r \
+age1kza7pfshy7xwygf9349zgmk7x53mquvedgw9r98qwyyqhssh830qqjzlsw \
+> "$HOME/secret_file"
+#+END_EXAMPLE
+
+The resulting ~secret-file~ is a binary blob with a plaintext header
+indicating how the blob was encrypted (which version of age was used,
+which public key was used).
+
+****** Encryption through ~bklog~
+~bklog~ may instructed to encrypt files via the ~-e~ and ~-r [pubkey
+string]~ options. An example is shown below:
+
+#+BEGIN_EXAMPLE
+$ gpspipe -r | bklog -e \
+-r age1kza7pfshy7xwygf9349zgmk7x53mquvedgw9r98qwyyqhssh830qqjzlsw \
+-r age1ce3pvzrqfcn2pc6zqzglc8ac8yjk3fzukpy08cesqjjwns53xywqmaq7xw \
+-r age1pu5usxm743sx7rf22985xv2f4s0luzv6r6yx4fa7p8c2zyvp9fvqus2xr5 \
+-o "$HOME/Location"
+#+END_EXAMPLE
+
+~bklog~ may be instructed via the ~-e~ and ~-R~ options to watch a
+directory in order to locate public key strings in its files. ~bklog~
+reads the first line of each file and interprets it as a public key
+string.
+
+In this example, the strings beginning with ~age1...~ are
+bech32-formatted public key strings. Please see the [[*Key Generation][Key Generation]]
+section for an explanation.
+
+Since ~age~ also accepts ~ssh~ public key strings, these may also be
+used if they are of the following form (no comment).
+
+: ssh-rsa AAAAB3NzaC1yc2EAAAADAQABA…AACAQDLnJbPs7CjwPT+OxXd
+
+***** Decryption Commands
+Files may be decrypted using a command similar to:
+
+#+BEGIN_EXAMPLE
+cat location.gpx.age | age -d -i key.txt > location.gpx
+#+END_EXAMPLE
+
+The version of ~age~ used to perform the encryption
+
** Operating Procedures
*** Initial Startup
+See OEM (Ozzmaker) [[https://ozzmaker.com/berrygps-berrygps-imu-quick-start-guide/][quickstart guide for the BerryGPS-IMU]].
+
+**** Physical Setup
+
+BerryGPS-IMU must be electrically connected to the correct pins on the
+GPIO header of a Raspberry Pi Zero W.
+
+*Optional*: stack together with PiZ Uptime 2.0 module. No GPIO pins
+conflict so a simple stacking and soldering with long header pins is
+possible.
+
+**** Software Setup
+***** Install Executables
+
+Install Raspbian 10 Buster onto an SD card image. See the Raspberry Pi
+Foundation [[https://www.raspberrypi.org/documentation/installation/installing-images/README.md][installation instructions]]. Configure WiFi to permit log
+file transfer. Configure SSH to permit remote administration via the
+command line interface.
+
+Make sure to install the ~unattended-upgrades~ package to make sure
+the latest security patches for packages are installed. See [[https://linux-audit.com/using-unattended-upgrades-on-debian-and-ubuntu/][this page]]
+for a description of how ~unattended-upgrades~ works.
+
+Install ~gpsd~, ~gpspipe~, ~git~, and this repository for location
+logging capability.
+
+Install ~syncthing~ for log file transfer capability.
+
+Place ~age~ binary (the one compiled for ARM CPU architecture for
+Linux) in ~$HOME/.local/bin~.
+
+***** Disable Swap File
+Since standard Raspbian 10 (Buster) install involves copying
+unencrypted file system image to SD card which is mounted by the
+Raspberry Pi, system memory may be written to disk in the form of a
+Swap file as described [[https://ideaheap.com/2013/07/stopping-sd-card-corruption-on-a-raspberry-pi/][here]]. In order to reduce the chance that
+location log data is ever written to disk, swap file functionality
+must be disabled[fn:ideaheap_20130731_disableswap].
+
+Raspbian 10 uses dphys-swapfile to manage a swap file. It may be
+disabled persistently[fn:rpf_20190702_disableswappersist] by running
+the following command:
+
+: sudo systemctl disable dphys-swapfile.service
+
+To view the status of the swap file in Raspbian 10, run ~free -m~:
+
+#+BEGIN_EXAMPLE
+pi@ninfacyzga-01:~$ free -m
+ total used free shared buff/cache available
+Mem: 432 86 36 21 309 268
+Swap: 99 0 99
+#+END_EXAMPLE
+
+After disabling the swap file and rebooting:
+
+#+BEGIN_EXAMPLE
+pi@ninfacyzga-01:~$ free -m
+ total used free shared buff/cache available
+Mem: 432 89 214 3 128 289
+Swap: 0 0 0
+#+END_EXAMPLE
+
+[fn:ideaheap_20130731_disableswap] Explanation:
+https://ideaheap.com/2013/07/stopping-sd-card-corruption-on-a-raspberry-pi/
+
+[fn:rpf_20190702_disableswappersist] Persistant disabling of swap in
+Raspbian 10 Buster:
+https://www.raspberrypi.org/forums/viewtopic.php?p=1490692&sid=5c596a124b7805d6b10dab8d3d7caf16#p1490692
+
+***** Automatic Start Configuration
+
+It is recommended to create a daily ~cron~ job that executes a bash
+script that starts ~bklog~ jobs to record location along with other
+types of data recording. An example of such a script is below:
+
+#+BEGIN_EXAMPLE
+#!/bin/bash
+
+# Log location
+gpspipe -r | /bin/bash "$HOME/.local/bin/bklog" -c -e -z "UTC" -t "/dev/shm" \
+ -r age1kza7pfshy7xwygf9349zgmk7x53mquvedgw9r98qwyyqhssh830qqjzlsw \
+ -r age1ce3pvzrqfcn2pc6zqzglc8ac8yjk3fzukpy08cesqjjwns53xywqmaq7xw \
+ -R "$HOME/.config/bklog/recipients" -w ".nmea" -b "300" -B "day" \
+ -o "$HOME/Sync/Evanescent_Location" -l "location" \
+ -p "gpsbabel -i nmea -f - -o gpx -F - " ".gpx" \
+ -p "gpsbabel -i nmea -f - -o kml -F - " ".kml" &
+# Log pressure
+python ~/.local/bin/bmp388.py | /bin/bash "$HOME/git-OC/ninfacyzga-01/exec/bklog" \
+ -c -e -z "UTC" -t "/dev/shm" \
+ -r age1kza7pfshy7xwygf9349zgmk7x53mquvedgw9r98qwyyqhssh830qqjzlsw \
+ -r age1ce3pvzrqfcn2pc6zqzglc8ac8yjk3fzukpy08cesqjjwns53xywqmaq7xw \
+ -R "$HOME/.config/bklog/recipients" -w ".txt" -b "300" -B "day" \
+ -o "$HOME/Sync/Evanescent_Location" -l "pressure" &
+#+END_EXAMPLE
+
+This script, if it were saved at
+~"$HOME/.local/bin/cron/dailylog.sh"~ would then be added as a
+line in the ~crontab~ file as shown below:
+
+#+BEGIN_EXAMPLE
+$ crontab -e
+0 0 * * * /bin/bash ~/.local/bin/cron/dailylog.sh
+@reboot /bin/bash ~/.local/bin/cron/dailylog.sh
+#+END_EXAMPLE
+
+In the example script, the options are:
+
+: -c : tells bklog to compress output
+: -e : tells bklog log to encrypt output
+: -r : tells bklog to interpret the next argument as a pubkey string
+: -R : tells bklog to interpret the next argument as a directory
+: where public keys may be found (first line of each file is
+: read).
+: -o : tells bklog to write output files to the directory represented
+: -t : tells bklog to interpret the next argument as a directory
+: for storing temporary files
+: by the next argument
+: -p : tells bklog a command string through which output is piped
+: before being compressed and encrypted. Also expected is a
+: file extension to be appended before the compression and
+: encryption file extensions.
+: -w : tells bklog to save the unprocessed stdin with a specified
+: file extension (instead of the default '.stdin').
+: -b : tells bklog how long each buffer round (time between file
+: writes) lasts in seconds.
+: -B : specifies the time-to-live for the bklog script. A valid value may
+: one of the time elements such as "day" or "hour".
+: -l : specfies a custom string to be used in output file names to
+: help differentiate tar files produced via bklog from different
+: sources of data.
+: -z : specifies a time zone to be used to determine the script time-to-live.
+: By default, bklog uses whatever time is specified by the TZ
+: environment variable.
+
+***** Log Transfer Configuration
+Log files may be shared to other machines via ~syncthing~. See [[https://docs.syncthing.net/][this]]
+manual for how to set up a shared folder and add Ninfacyzga-01 as a
+device. Syncthing's directory synchronization capability allows a
+remote machine to delete files from Ninfacyzga-01 by deleting from the
+shared folder that they both share.
+
+When log files are removed from Ninfacyzga-01 is not within the scope
+of this document.
+
+***** Key Generation
+An ~age~ encryption key may be generated like so:
+#+BEGIN_EXAMPLE
+$ umask # Gets current umask
+0022 # Note: This is the default umask for Raspbian 10
+$ umask 066 # So key.txt will have no perms except for owner (you)
+$ umask # Confirm umask set to 066
+0066
+$ age-keygen > key.txt
+Public key: age1pu5usxm743sx7rf22985xv2f4s0luzv6r6yx4fa7p8c2zyvp9fvqus2xr5
+$ ls -al key.txt
+-rw------- 1 baltakatei baltakatei 184 Jun 29 18:28 key.txt
+$ umask 0022 # Return umask to default value
+$ umask
+0022
+#+END_EXAMPLE
+
+The resulting public/private keypair data looks like:
+#+BEGIN_EXAMPLE
+$ cat key.txt
+# created: 2020-06-29T18:01:56Z
+# public key: age1pu5usxm743sx7rf22985xv2f4s0luzv6r6yx4fa7p8c2zyvp9fvqus2xr5
+AGE-SECRET-KEY-1NEUU5U2XGZGL9UYWNPU5DL99TGJJHFSN4F2E2WCCSDJJ6L5ZMLESNTVTU0
+#+END_EXAMPLE
+
+The file ~key.txt~ is not password-protected by default and should be
+secured like an SSH public key should. The ~$ umask 066~ command run
+before the ~$ age-keygen > key.txt~ command ensures ~key.txt~ will not
+be readable, writeable, or executable to anyone except the owner
+(you).
+
*** Normal Startup
+Turn on Ninfacyzga-01 by supplying 5VDC power to the Raspberry Pi. No
+further interaction should be required.
+*** Normal Operation
+No interaction beyond continually supplying approximately 100mA of
+5VDC power and occasionally removing log files to conserve disk space
+is required.
+**** Log Transfer
+Log files may be transferred by use of ~syncthing~ shared folders.
+**** Automatic Updates
+The ~automatic-upgrades~ package, if installed, should automatically
+install security patches to packages installed via ~apt~.
*** Normal Shutdown
+The system may be shutdown via SSH by running:
+
+: $ sudo shutdown -r 0
+
*** Unscheduled Shutdown
+Ninfacyzga-01 as described and setup should tolerate unscheduled power
+loss. Log files being written every 60 seconds means, at most, 60
+seconds worth of location data may be lost.
*** End of Life Disposal
+LiPo batteries used by the PiZ Uptime 2.0 module should be disposed of
+properly with their potential ignitability in mind, especially if they
+are not fully discharged.
+
+Consult your local municipality for its "E-Waste Disposal" (or
+equivalent) policy. Metals used in the Raspberry Pi and related
+components may be recycled.
+Take extra precuation if lead solder was used in assembling the
+electronics. Consumer electronics in early 21st century should use
+lead-free solder.
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