190 lines
6.9 KiB
Markdown
190 lines
6.9 KiB
Markdown
---
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layout: post
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title: "Experiments In Owning Data"
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date: 2019-01-20
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comments: true
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tags: freebsd
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---
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I have been working for a while to own most of the data I generate. Thought I
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would write down what I mean by that and how I am doing so far.
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Before this effort most of my data where spread across many proprietary
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services, some free, some paid. I had always felt I had restricted control over
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them, and I had to find out some free tier [restrictions the hard
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way](https://www.quora.com/What-happens-to-your-older-photos-once-you-go-over-the-free-200-limit-on-Flickr-without-turning-pro).
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So this started as an effort to
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1. organize all the things that I wanted in a central (virtual) place.
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2. and fine grain control over who has access to the data.
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However all of the service that I looked into was made for exactly what I wanted
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to avoid - a free service that monetizes based on my personal data, they do take
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my money to provide "upgrades", and my data may not be mined (or maybe - no way
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to ensure that). Also service behaviors were sometimes opaque and confusing,
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even [causing people to loose
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data](https://productforums.google.com/forum/#!topic/apps/RIHSJ4LIXwE).
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Another thing that stood out was how inflexible these services were. Mostly
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designed as big monoliths that does not play well with others. For e.g google
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photos is really nice - but what if I want to run an imagemagic script over all
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of the photos I have? I think there is someway to do this if you poke at the
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photos API, however the friction is too much compared to just mounting them over
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webdav or fuse. For a lot of these services Linux was a second class citizen,
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and FreeBSD an undiscovered species. I understand these are not common
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requirements, but I wanted the system to work with things I use and have.
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## Hardware
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At the moment, what I call my personal data is ~500GB, that's all the pictures,
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emails documents, code and other things that I have. Assuming a 3 fold growth (probably too low?) I decided that I need around 2.5TB storage. Other requirements were,
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1. connected to reasonably fast internet and reliable power
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2. cheap (remember, migrating out of this system is going to be really painful)
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After some consideration I decided to not to host my hardware, I move around a
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lot and state of home internet in Germany is not where I'd like it to be.
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Requirements for storage made most of the cloud providers unfeasible (_3TB EBS is
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~$350/month_).
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I finally settled on a physical machine from hetzner [server
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auction](https://www.hetzner.com/sb). Server auction is where they sell their
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older generation machines (read: sandy bride/ivy bridge) at a steep discount. I
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was able to get a Xeon E3 with 32GB ECC ram and 2x3TB disks for 30 EUR a month.
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It could have been a bit cheaper if had gone with an i7 machine (newer cpu too)
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instead. But they don't ECC RAM. Intel is very adamant in not supporting ECC in
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"desktop class" processors.
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## Installation
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Installation was piece of cake, hetzner allows you to boot the server into
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`freebsd rescue mode` where they point server to PXE boot from a
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[`mfsbsd`](https://mfsbsd.vx.sk/) disk and lets you ssh, and then you can start
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installing `FreeBSD` (one can follow a similar procedure for Linux distros with
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a linux rescue image..)
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## Security
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Even though the main goal is to avoid mass surveillance, I also wanted to avoid
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data leaks because of unplanned events - me not paying bills, hardware failures
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etc. The solution was to encrypt the disks, so that at rest nobody can sniff
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data out of them.
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This became a challenge because getting access to KVM in hetzner environment is
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not instant. One need to send them a request and a human mails you kvm access
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creds for an hour (they are usually fast though). This is a challenge because
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every time I need to reboot the server I would need to get KVM access, type in
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my password over KVM (also not sure how much of that encryption I can trust..)
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and let the machine boot.
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### Two Zpools approach
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However a friend of mine had the solution, the idea is to have two
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[zpool](https://en.wikipedia.org/wiki/ZFS)s. one, unencrypted that holds the OS
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and the other encrypted that holds data.
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Both of the zpools are in
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[raid1](https://en.wikipedia.org/wiki/Standard_RAID_levels), meaning they are
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mirrored to two physical disks, hence as long as both disks don't fail together,
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we won't have any problems.
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```
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disk1
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+------------------------+
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| pool1| pool2 |
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| unenc| enc |
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+------------------------+
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disk2
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+------------------------+
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| pool1| pool2 |
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| unenc| enc |
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+------------------------+
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```
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Roughly this how it works: When machine boots, it boots off the plain zpool, and
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gets to the custom rc.script `geli0` installed by us
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```
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#!/bin/sh
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#
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# PROVIDE: geli0
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# BEFORE: disks
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# REQUIRE: initrandom
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# KEYWORD: nojail
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. /etc/rc.subr
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name="geli0"
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start_cmd="geli0_start"
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stop_cmd=":"
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required_modules="geom_eli:g_eli"
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geli0_start()
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{
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zfs mount -av
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/etc/rc.d/hostid start
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/etc/rc.d/hostname start
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/etc/rc.d/netif start
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/etc/rc.d/routing start
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/etc/rc.d/sshd start
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echo -n "Waiting for zpool:encrypted to become available, "
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echo -n "press enter to continue..."
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echo
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while true; do
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if [ -e /dev/ada0p4.eli -a -e /dev/ada1p4.eli ]; then
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break
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fi
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read -t 5 dummy && break
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done
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/etc/rc.d/sshd stop
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pkill sshd
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/etc/rc.d/routing stop
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/etc/rc.d/netif stop
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# /etc/rc.d/devd stop
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}
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load_rc_config $name
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run_rc_command "$1"
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```
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This script pauses the boot, setups up some essential services related to
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`network`, `ssh` and waits for the second set of disks to be available. The
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machine is essentially waiting for me to decrypt the disks, and I can do that by
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ssh-ing to the box and running `decryptvol.sh` (contents below)
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```
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#!/bin/sh
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#
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# The passphrase for both disks is the same.
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# Read it once and decrypt the disks.
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#
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set -e
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echo -n "Enter passphrase: "
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stty -echo
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IFS="" read -r passphrase
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stty echo
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echo
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echo $passphrase | geli attach -k /boot/keys/ada1p4.key -j - /dev/ada1p4
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echo $passphrase | geli attach -k /boot/keys/ada0p4.key -j - /dev/ada0p4
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```
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As soon as the disks are available the `geli0` scripts resumes regular boot, but
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now with access to encrypted data.
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## Conclusion and part 2
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With this setup I have a place to store my data and its secure from data mining
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by third party service providers. One bit that worries me is that someone can
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coerce hetzner to attack the hardware itself, but I am not sure its something I
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can solve at the moment.
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However this is only a part of the puzzle. Strictly speaking I have my data
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platform so as to speak, and now I need services that integrates this with other
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devices that generate and consume data. This post is already longer than I
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anticipated, so I will write about software and other services in a follow up.
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