## Programmatically Obtain Shortcut Icons

For a side project, I just needed to download the favicons of brands to visually augment a web portal :)

Historically, that icon was named favicon.ico, and stored in the root directory of the website. However, nowadays the icon is typically called shortcut icon, and there are tons of options on how to get it into the browers’ tab pane… Very rarely it’s still named favicon.ico. It’s often not even an ICO file, but a PNG image or an SVG graph. And developers often refer to it from within a webpage’s HTML code using a <link ...> tag.

However, it’s pretty convinient to create a link to a brand as it properly resembles the brand’s official log!

## Alternatives

So I heard you don’t like Google? There is at least one alternative: https://api.faviconkit.com/twitter.com/144.
There is also PHP tool for that, if you want to self-host such a tool: https://github.com/ao/favicons.

## Run your Private Firefox Sync Server

As I’m working on multiple machines (two desks at work, one desk at home, laptop, …) I’ve always been looking for a way to sync my browsers… Of course, I knew about Firefox’ sync, but I obviously don’t want to store my private browsing data in Mozilla’s cloud! Every once in a while I stumbled upon articles and posts suggesting to run a private syncserver. However, every time when looking into that project it left an uncomfortable impression: (i) you need to manually compile some 3rd party software, (ii) the whole thing seems very complex/unclean, as it requires an account server and a sync server and may work with Mozilla’s account server (but how?), and (iii) the sync project was once already abandoned (Firefox Weave was discontinued because too complex and unreliable)… Therefore, I never dared to give it a try.

Today, when I’ve again been frustrated with that fragmented situation, I saw that Mozilla’s syncserver sources contain a Dockerfile! It probably has been there for ages, but I never recognised it.. Even if that project may be a mess, in a container environment it’s pretty easy to give it a try (and clean it, if unsatisfied)! That changes everything! :P

So I changed everything, and tooted about it. Various people then convinced me to write this article. And I also learnt that Epiphany can do Firefox’ sync out of the box!

## Get the Syncserver Running

Running your own syncserver using Docker is pretty straight forward. This how-to is based on the project’s readme at GitHub:mozilla-services/syncserver, but I’m using docker-compose and I deployed the service behind an Nginx proxy. You can of course skip the proxy settings and have it run locally or something.

### Get the Code

Just clone the sources from GitHub:

You should now see a new directory syncserver containing all the sources, including a Dockerfile.

### Build a Docker Image

Change into the project’s directory, that contains the Dockerfile and build a new Docker image using:

That will take a while, but when it’s finished you’ll find a new image (double check with docker images).

The provided Dockerfile is basically sufficient, but in my scenario I also need to properly declare an exposed port. So I edited that file and added

See also the diff of my commit. I decided to take port 5000, as the user running the syncserver is unpriviledged (so :80 and :443 are not an option) and :5000 is the example in the project’s readme ;-)

### Create a Docker-Compose Configuration

Docker-Compose makes it easier to assemble and handle multiple containers in a medium complex environment.

My compose config looks like this:

This snippet encodes for a container named firefox-sync, which is based on the image syncserver:latest. It mounts the host’s directory /path/to/mozilla-sync/share into the container as /syncshare (I’d like to store my stuff outside of the container). In addition it declares some environment:

• SYNCSERVER_PUBLIC_URL tells the service the actual URL to your instance.
• SYNCSERVER_SECRET should be complicated as it is used to generate internal certificates and stuff.
• SYNCSERVER_SQLURI tell the service which database to use. I point it to the directory (/syncshare) that was mounted into the container, so it will actually store the database on the host.
• SYNCSERVER_BATCH_UPLOAD_ENABLED is, if I understand correctly, an option to allow for uploading everything immediately…?
• SYNCSERVER_FORCE_WSGI_ENVIRON must be set to true, if SYNCSERVER_PUBLIC_URL doesn’t match the actual URL seen by the python tool. In my case, I would connect to SYNCSERVER_PUBLIC_URL, which is however the Nginx proxy, which forwards the traffic to the syncserver. However, the syncserver will see a different request (e.g. it’s internally not https anymore) and complain.

The last two variables (VIRTUAL_HOST and VIRTUAL_PORT) just configure the reverse proxy that I’m using. Feel free to drop these lines if you want to expose the service directly to the network, but then you need to add a port forwarding for that container, such as

which forwards traffic at your machine’s HTTP port (:80, use a different port if you’re already running a web server) to the service’s port in the container (:5000).

If you have a porper Docker-Compose configuration, just run

to start the service. Et voilà, you should be able to access the service at the configured SYNCSERVER_PUBLIC_URL :)

### Configure Firefox to use your Private Sync Server

First make sure you’re signed out in the browser! That means, about:preferences#sync should not show your identity and instead provide a button to sign in.

Then, open about:config and search for identity.sync.tokenserver.uri. By default, it will be set to Mozilla’s sync server https://token.services.mozilla.com/1.0/sync/1.5. Edit that field and point it to your SYNCSERVER_PUBLIC_URL plus /token/1.0/sync/1.5. Thus, in our example above I’d set it to https://firefox-sync.example.com/token/1.0/sync/1.5.

Now go back to about:preferences#sync and sign in with your Mozilla account. Yes, correct. You still need an account at Mozilla! But that is just for authentication… There is an option to also run a private account server (see Run your own Firefox Accounts Server), but that’s even more complicated. And as I need a Mozilla account anyway to develop my AddOns, I skipped that additional hassling..

### Open Issues and Troubleshooting

There are still a few issues with different clients. For example, I don’t know how to tell Epiphany to use my private syncserver instead of Mozilla’s public instance.. In addition, there is apparently no Firefox in the F-Droid repository, that properly supports sync…

For general debugging and troubleshooting, search engines are a good start.. In addition, I learnt that there is about:sync-log, which contains very detailed error messages in case of problems.

## Eventually…

… I got my sync! #hooray

It’s still crisply and I didn’t test it too much, but so far it’s looking pretty good.

## Mount multiple subvolumes of a LUKS encrypted BTRFS through pam_mount

Some days ago, @daftaupe@mamot.fr convinced me on Mastodon to give BTRFS a try. That’s actually been a feature on my list for some time already, and now that I need to switch PCs at work I’m going for it. However, this post wouldn’t exist if everything went straight forward.. ;-)

## The Scenario

I have a 1TB SSD that I want to encrypt. It should automatically get decrypted and mounted to certain places when I log in. pam_mount can do that for you, and I’ve already been using that a lot in different scenarios. However, with BTRFS it’s a bit different. With any other file systems you would create a partition on the hard drive, which is then LUKS encrypted. This has the drawback, that you need to decide on the partition’s size beforehand!

With BTRFS you can just encrypt the whole drive and use so-called subvolumes on top of it. Thus, you’re a bit more flexible by creating and adjusting quotas as required at any point in time (if at all…), but (or and!) the subvolumes are not visible unless the device is decrypted.

Let’s have a look into that and create the scenario. I assume that the SSD is available as /dev/sdb. Then we can create an encrypted container using LUKS:

You’re not sure which cipher or key-size to choose? Just run cryptsetup benchmark to see which settings perform best for you. My CPU, for example, comes with hardware support for AES, thus the AES ciphers show a significantly higher throughput. If you’re still feeling uncompfortable with that step, I recommend reading the sophisticated article at the ArchLinux’ wiki on dm-crypt/Device encryption.

We can now open the encrypted device using

This will create a node in /dev/mapper/mydrive, which represents the decrypted device.

Next, we’ll create a BTRFS on that device:

That’s indeed super fast, isn’t it!? I also couldn’t believe it.. ;-)

We can now mount the device, for example to /mnt/mountain:

So far, the file system is completely empty. But as it’s a BTRFS, we can create some subvolumes. Let’s say, we want to create a volume for our \$HOME, and as we’re developing this website, we also want to create a volume called www:

So we have two subvolumes in that file system: home (id 258) and www (id 259). We could now mount them with

But we want the system to do it automatically for us, as we login.

So unmount everything and close the LUKS container:

## PamMount can Decrypt and Mount Automatically

I’m using pam_mount already for ages! It is super convenient. To get your home automatically decrypted and mounted, you would just need to add the following lines to your /etc/security/pam_mount.conf.xml:

Given this, PAM tries to mount the respective subvolumes of the disk (identified by the UUID a1b20e2f-049c-...) to /home/user and /var/www as soon as YOU logs in.

Here, I am using UUIDs to identify the disks. You can still use /dev/sdb (or similar), but there is a chance, that the disks are recognised in a different sequence with the next boot (and /dev/sdb may become /dev/sdc or something…). Plus, the UUID is invariant to the system – you can put the disk in any other machine and it will have the same UUID.

To find the UUID of your disk you can use blkid:

## The Problem

As said above, with BTRFS you’ll have your partitions (called subvolumes) right in the filesystem – invisible unless decrypted. So, what is PAM doing? It discovers the first entry in the pam_mount.conf.xml configuration, which basically says

mount a1b20e2f-049c-... with some extra options to /home/user when YOU logs in

PAM is also smart enough to understand that a1b20e2f-049c-... is a LUKS encrypted device and it decrypts it using your login password. This will then create a node in /dev/mapper/_dev_sdb, representing the decrypted device. And eventually, PAM mounts /dev/mapper/_dev_sdb to /home/user. So far so perfect.

But as soon as PAM discovers the second entry, it tries to do the same! Again it detects a LUKS device and tries to decrypt that. But unfortunately, there is already /dev/mapper/_dev_sdb!? Thus, opening the LUKS drive fails and you’ll find something like that in your /var/log/auth.log:

First it seems annoying that it doesn’t work out of the box, but at least it sounds reasonable that PAM cannot do what you what it to do..

## The Solution

… is quite easy, even though it took me a while to figure things out…

As soon as the first subvolume is mounted (and the device is decrypted and available through /dev/mapper/_dev_sdb), we have direct access to the file system! Thus, we do not neet to tell PAM to mount /dev/disk/by-uuid/a1b20e2f-049c-..., but we can use /dev/mapper/_dev_sdb. Or even better, we can use the file system’s UUID now, to become invariant to the sdb-variable. If you run blkid with the device being decrypted you’ll find an entry like this:

You see, the new node /dev/mapper/_dev_sdb also carries a UUID, actually representing the BTRFS :)
This UUID was by the way also reported by the mkfs.btrfs call above.

What does that mean for our setup? When we first need a subvolume of an encrypted drive we need to use the UUID of the parent LUKS container. For every subsequent subvolume we can use the UUID of the internal FS.

Transferred to the above scenario, we’d create a /etc/security/pam_mount.conf.xml like that:

Note the different UUIDs? Even though both mounts origin from the same FS :)

## Open Problems

Actually, I wanted to have my home in a raid of two devices, but I don’t know how to tell pam_mount to decrypt two devices to make BTRFS handle the raid..? The only option seems to use mdadm to create the raid, but then BTRFS just sees a single device and, therefore, cannot do its extra raid magic

If anyone has an idea on that issue you’ll have my ears :)

## Thunderbird 60+ is missing calendars

I’m running Thunderbird to read emails on my desktops. And I’m using the Lightning plugin to manage calendars, evens, and tasks.

However, since I updated to Thunderbird 60 some weeks ago, Lightning strangely seems to be broken. The Add-ons manager still lists Lightning as properly installed, but there the “Events and Tasks” menu is missing, as well as the calendar/tasks tabs and the calendar settings in the preferences. As I’ve been pretty busy with many other things, I didn’t study the problem - hoping that the bug gets fixed in the meantime - but living without the calendar addon is cumbersome. And today it became annoying enough to make me investigate this…

There seems to be various issues with calendars in the new Thunderbird version: Mozilla provides an extensive support page dedicated to this topic. Sadly, none of these did help in my case..

I then made sure that the versions of Thunderbird and Lightning are compatible (both are 1:60.0-3~deb9u1 for me):

Eventually, I stumbled upon a thread in the German Debian forums: Thunderbird 60 - Lightning funktioniert nicht. And they figured out, that it may be caused by missing language packs for Lightning… Indeed, I do have language packs for Thunderbird installed (de and en-gb), that are not installed for Lightning:

And it turns out, that this was a problem! Thunderbird apparently wouldn’t run Lightning unless it has all required language packs installed. After installing the missing language packs (aptitude install lightning-l10n-de lightning-l10n-en-gb), the extension is again fully working in Thunderbird! How unsatisfactory…

All that may be cause by a missing dependency..? Even though thunderbird recommends lightning, thunderbird-l10n-de (and similiar) do not recommend lightning-l10n-de. Not exactly sure how, but maybe the dependencies should be remodelled…?

## Native SSH server on LinageOS

I finally trashed my shitty Shift5.2 and got a spare OnePlus One from a good colleague.

tldr: scroll down to Setup of SSH on LineageOS.

I strongly discourage everyone from buying a ShiftPhone. The Phone was/is on Android patch level from 2017-03-05 – which is one and a half year ago! Not to mention that it was running an Android 5.1.1 in 2018… With soo many bugs and security issues, in my opinion this phone is a danger to the community! And nobody at Shift seemed to really care…

However, I now have a OnePlus One, which is supported by LineageOS - the successor of CyanogenMod. So, first action was installing LineageOS. Immediately followed by installing SU to get root access.

Next, I’d like to have SSH access to the phone. I did love the native SSH server on my Galaxy S2, which used to run CyanogenMod for 5+ years. Using the SSH access I was able to integrate it in my backup infrastructure and it was much easier to quickly copy stuff from the phone w/o a cable :)

The original webpage including a how-to for installing SSH on CyanogenMod has unfortunately vanished. There is a copy available from the WayBackMachine (thanks a lot guys!!). I still thought dumping an up-to-date step-wise instruction here may be a good idea :)

## Setup of SSH on LineageOS

The setup of the native SSH server on LineageOS seems to be pretty similiar to the CyanogenMod version. First you need a shell on the phone, e.g. through adb, and become root (su). Then just follow the following three steps:

### Create SSH daemon configuration

You do not need to create a configuration file from scratch, you can use /system/etc/ssh/sshd_config as a template. Just copy the configuration file to /data/ssh/sshd_config;

Just make sure you set the following things:

• PermitRootLogin without-password
• PubkeyAuthentication yes
• PermitEmptyPasswords no
• ChallengeResponseAuthentication no
• Subsystem sftp internal-sftp

Update: Ed Huott reported:

There was one additional step I needed to make it work. It was necessary to set StrictModes no in /data/ssh/sshd_config in order to keep sshd from failing to start due to bad file ownership/permissions on the /data/.ssh directory and files as well as the parent /data directory.

This is because the owner:group of /data is system:system which doesn’t match either root or shell owner:group used for /data/.ssh and its contents. I felt that setting StrictModes no was a better solution than messing with the owner:group of the /data directory!

### Setup SSH keys

We’ll be using SSH-keys to authenticate to the phone. If you don’t know what SSH keys are, or how to create them, you may go to an article that I wrote in 2009 (!!) or use an online search engine.

First, we need to create /data/.ssh on the phone (note the .!) and give it to the shell user:

Second, we need to store our public SSH key (probably stored in ~/.ssh/id_rsa.pub on your local machine) in /data/.ssh/authorized_keys on the phone. If that file exists, just append your public key into a new line. Afterwards, handover the authorized_keys file to the shell user:

### Create a start script

Last but not least, we need a script to start the SSH service. There is again a template available in /system/bin/start-ssh. Just copy the script to /data/local/userinit.d/:

Finally, we just need to update the location of the sshd_config to /data/ssh/sshd_config in our newly created /data/local/userinit.d/99sshd script (in the template it points to /system/etc/ssh/sshd_config, there are 2 occurences: for running the daemon w/ and w/o debugging).

## That’s it

You can now run /data/local/userinit.d/99sshd and the SSH server should be up and running :)

Earlier versions of Android/CyanogenMod auto-started the scripts stored in /data/local/userinit.d/ right after the boot, but this feature was removed with CM12.. Thus, at the moment it is not that easy to automatically start the SSH server with a reboot of your phone. But having the SSH daemon running all the time may also be a bad idea, in terms of security and battery…