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Openssh taking minutes to become available, booting takes half an hour ... because your server waits for a few bytes of randomness

Linux

So, your machine now needs minutes to boot before you can ssh in where it used to be seconds before the Debian Buster update?

Problem

Linux 3.17 (2014-10-05) learnt a new syscall getrandom() that, well, gets bytes from the entropy pool. Glibc learnt about this with 2.25 (2017-02-05) and two tries and four years after the kernel, OpenSSL used that functionality from release 1.1.1 (2018-09-11). OpenSSH implemented this natively for the 7.8 release (2018-08-24) as well.

Now the getrandom() syscall will block1 if the kernel can't provide enough entropy. And that's frequenty the case during boot. Esp. with VMs that have no input devices or IO jitter to source the pseudo random number generator from.

First seen in the wild January 2017

I vividly remember not seeing my Alpine Linux VMs back on the net after the Alpine 3.5 upgrade. That was basically the same issue.

Systemd. Yeah.

Systemd makes this behaviour worse, see issues #4271, #4513 and #10621.
Basically as of now the entropy file saved as /var/lib/systemd/random-seed will not - drumroll - add entropy to the random pool when played back during boot. Actually it will. It will just not be accounted for. So Linux doesn't know. And continues blocking getrandom(). This is obviously different from SysVinit times2 when /var/lib/urandom/random-seed (that you still have lying around on updated systems) made sure the system carried enough entropy over reboot to continue working right after enough of the system was booted.

#4167 is a re-opened discussion about systemd eating randomness early at boot (hashmaps in PID 0...). Some Debian folks participate in the recent discussion and it is worth reading if you want to learn about the mess that booting a Linux system has become.

While we're talking systemd ... #10676 also means systems will use RDRAND in the future despite Ted Ts'o's warning on RDRAND [Archive.org mirror and mirrored locally as 130905_Ted_Tso_on_RDRAND.pdf, 205kB as Google+ will be discontinued in April 2019].
Update: RDRAND doesn't return random data on pre-Ryzen AMD CPUs (AMD CPU family <23) as per systemd bug #11810. It will always be 0xFFFFFFFFFFFFFFFF (264-1). This is a known issue since 2014, see kernel bug #85991.

Debian

Debian is seeing the same issue working up towards the Buster release, e.g. Bug #912087.

The typical issue is:

[    4.428797] EXT4-fs (vda1): mounted filesystem with ordered data mode. Opts: data=ordered
[ 130.970863] random: crng init done

with delays up to tens of minutes on systems with very little external random sources.

This is what it should look like:

[    1.616819] random: fast init done
[    2.299314] random: crng init done

Check dmesg | grep -E "(rng|random)" to see how your systems are doing.

If this is not fully solved before the Buster release, I hope some of the below can end up in the release notes3.

Solutions

You need to get entropy into the random pool earlier at boot. There are many ways to achieve this and - currently - all require action by the system administrator.

Kernel boot parameter

From kernel 4.19 (Debian Buster currently runs 4.18 [Update: but will be getting 4.19 before release according to Ben via Mika]) you can set RANDOM_TRUST_CPU at compile time or random.trust_cpu=on on the kernel command line. This will make recent Intel / AMD systems trust RDRAND and fill the entropy pool with it. See the warning from Ted Ts'o linked above.

Update: Since Linux kernel build 4.19.20-1 CONFIG_RANDOM_TRUST_CPU has been enabled by default in Debian.

Using a TPM

The Trusted Platform Module has an embedded random number generator that can be used. Of course you need to have one on your board for this to be useful. It's a hardware device.

Load the tpm-rng module (ideally from initrd) or compile it into the kernel (config HW_RANDOM_TPM). Now, the kernel does not "trust" the TPM RNG by default, so you need to add

rng_core.default_quality=1000

to the kernel command line. 1000 means "trust", 0 means "don't use". So you can chose any value in between that works for you depending on how much you consider your TPM to be unbugged.

VirtIO (KVM, QEMU, ...)

For Virtual Machines (VMs) you can forward entropy from the host (that should be running longer than the VMs and have enough entropy) via virtio_rng.

So on the host, you do:

kvm ... -object rng-random,filename=/dev/urandom,id=rng0 -device virtio-rng-pci,rng=rng0,bus=pci.0,addr=0x7

and within the VM newer kernels should automatically load virtio_rng and use that.

You can confirm with dmesg as per above.

Or check:

# cat /sys/devices/virtual/misc/hw_random/rng_available
virtio_rng.0
# cat /sys/devices/virtual/misc/hw_random/rng_current
virtio_rng.0

Patching systemd

The Fedora bugtracker has a bash / python script that replaces the systemd rnd seeding with a (better) working one. The script can also serve as a good starting point if you need to script your own solution, e.g. for reading from an entropy provider available within your (secure) network.

Chaoskey

The wonderful Keith Packard and Bdale Garbee have developed a USB dongle, ChaosKey, that supplies entropy to the kernel. Hard- and software are open source.

Jitterentropy_RNG

Kernel 4.2 introduced jitterentropy_rng which will use the jitter in CPU timings to generate randomness.

modprobe jitterentropy_rng

This apparently needs a userspace daemon though (read: design mistake) so

apt install jitterentropy-rngd (available from Buster/testing).

The current version 1.0.8-3 installs nicely on Stretch. dpkg -i is your friend.

But - drumroll - that daemon doesn't seem to use the kernel module at all.

That's where I stopped looking at that solution. At least for now. There are extensive docs if you want to dig into this yourself.

Update: The Linux kernel 5.3 will have an updated jitterentropy_rng as per Commit 4d2fa8b44. This is based on the upstream version 2.1.2 and should be worth another look.

Haveged

apt install haveged

Haveged is a user-space daemon that gathers entropy though the timing jitter any CPU has. It will only run "late" in boot but may still get your openssh back online within seconds and not minutes.

It is also - to the best of my knowledge - not verified at all regarding the quality of randomness it generates. The haveged design and history page provides and interesting read and I wouldn't recommend haveged if you have alternatives. If you have none, haveged is a wonderful solution though as it works reliably. And unverified entropy is better than no entropy. Just forget this is 2018 2019 :-).

early-rng-init-tools

Thorsten Glaser has posted newly developed early-rng-init-tools in a debian-devel thread. He provides packages at http://fish.mirbsd.org/~tg/Debs/dists/sid/wtf/Pkgs/early-rng-init-tools/ .

First he deserves kudos for naming a tool for what it does. This makes it much more easily discoverable than the trend to name things after girlfriends, pets or anime characters. The implementation hooks into the early boot via initrd integration and carries over a seed generated during the previous shutdown. This and some other implementation details are not ideal and there has been quite extensive scrutiny but none that discovered serious issues. Early-rng-init-tools look like a good option for non-RDRAND (~CONFIG_RANDOM_TRUST_CPU) capable platforms.

Linus to the rescue

Luckily end of September Linus Torvalds was fed up with the entropy starvation issue and the non-conclusive discussions about (mostly) who's at fault and ... started coding.

With the kernel 5.4 release on 25.11.2019 his patch has made it into mainline. He created a try_to_generate_entropy function that uses CPU jitter to generate seed entropy for the PRNG early in boot.

In the merge commit Linus explains:

This is admittedly partly "for discussion". We need to have a way forward for the boot time deadlocks where user space ends up waiting for more entropy, but no entropy is forthcoming because the system is entirely idle just waiting for something to happen.

While this was triggered by what is arguably a user space bug with GDM/gnome-session asking for secure randomness during early boot, when they didn't even need any such truly secure thing, the issue ends up being that our "getrandom()" interface is prone to that kind of confusion, because people don't think very hard about whether they want to block for sufficient amounts of entropy.

The approach here-in is to decide to not just passively wait for entropy to happen, but to start actively collecting it if it is missing. This is not necessarily always possible, but if the architecture has a CPU cycle counter, there is a fair amount of noise in the exact timings of reasonably complex loads.

We may end up tweaking the load and the entropy estimates, but this should be at least a reasonable starting point.

So once this kernel is available in your distribution, you should be safe from entropy starvation at boot on any platform that has hardware timers (I haven't encountered one that does not in the last decade).

Ted Ts'o reviewed the approach and was fine and Ahmed Dawish did some testing of the quality of randomness generated and that seems fine, too.

Updates

14.01.2019

Stefan Fritsch, the Apache2 maintainer in Debian, OpenBSD developer and a former Debian security team member stumbled over the systemd issue preventing Apache libssl to initialize at boot in a Debian bug #916690 - apache2: getrandom call blocks on first startup, systemd kills with timeout.

The bug has been retitled "document getrandom changes causing entropy starvation" hinting at not fixing the underlying issue but documenting it in the Debian Buster release notes.

Unhappy with this "minimal compromise" Stefan wrote a comprehensive summary of the current situation to the Debian-devel mailing list. The discussion spans over December 2018 and January 2019 and mostly iterated what had been written above already. The discussion has - so far - not reached any consensus. There is still the "systemd stance" (not our problem, fix the daemons) and the "ssh/apache stance" (fix systemd, credit entropy).

The "document in release notes" minimal compromise was brought up again and Stefan warned of the problems this would create for Buster users:

> I'd prefer having this documented in the release notes:
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=916690
> with possible solutions like installing haveged, configuring virtio-rng,
> etc. depending on the situation.

That would be an extremely user-unfriendly "solution" and would lead to 
countless hours of debugging and useless bug reports.

This is exactly why I wrote this blog entry and keep it updated. We need to either fix this or tell everybody we can reach before upgrading to Buster. Otherwise this will lead to huge amounts of systems dead on the network after what looked like a successful upgrade.

Some interesting tidbits were mentioned within the thread:

Raphael Hertzog fixed the issue for Kali Linux by installing haveged by default. Michael Prokop did the same for the grml distribution within its December 2018 release.

Ben Hutchings pointed to an interesting thread on the debian-release mailing list he kicked off in May 2018. Multiple people summarized the options and the fact that there is no "general solution that is both correct and easy" at the time.

Sam Hartman identified Debian Buster VMs running under VMware as an issue, because that supervisor does not provide virtio-rng. So Debian VMs wouldn't boot into ssh availability within a reasonable time. This is an issue for real world use cases albeit running a proprietary product as the supervisor.

16.01.2019

Daniel Kahn Gillmor wrote in to explain a risk for VMs starting right after the boot of the host OS:

If that pool is used by the guest to generate long-term secrets because it appears to be well-initialized, that could be a serious problem.
(e.g. "Mining your P's and Q's" by Heninger et al -- https://factorable.net/weakkeys12.extended.pdf)
I've just opened https://bugs.launchpad.net/qemu/+bug/1811758 to report a way to improve that situation in qemu by default.

So ... make sure that your host OS has access to a hardware random number generator or at least carries over its random seed properly across reboots. You could also delay VM starts until the crng on the host Linux is fully initialized (random: crng init done).
Otherwise your VMs may get insufficiently generated pseudo-random numbers and won't even know.

12.03.2019

Stefan Fritsch revived the thread on debian-devel again and got a few more interesting tidbits out of the developer community:

Ben Hutchings has enabled CONFIG_RANDOM_TRUST_CPU for Debian kernels from 4.19.20-1 so the problem is somewhat contained for recent CPU AMD64 systems (RDRAND capable) in Buster.

Thorsten Glaser developed early-rng-init-tools which combine a few options to try and get entropy carried across boot and generated early during boot. He received some scrutiny as can be expected but none that would discourage me from using it. He explains that this is for early boot and thus has initrd integration. It complements safer randomness sources or haveged.

16.04.2019

The Debian installer for Buster is running into the same problem now as indicated in the release notes for RC1. Bug #923675 has details. Essentially choose-mirror waits serveral minutes for entropy when used with https mirrors.

08.05.2019

The RDRAND use introduced in systemd to bypass the kernel random number generator during boot falls for a AMD pre-Ryzen bug as RDRAND on these systems doesn't return random data after a suspend / resume cycle. Added an update note to the systemd section above.

03.06.2019

Bastian Blank reports the issue is affecting Debian cloud images now as well as cloud-init generates ssh keys during boot.

10.07.2019

Added the update of jitterentropy_rng to a version based on upstream v2.1.2 into the Jitterentropy section above.

16.09.2019

The Linux Kernel Mailing List (LKML) is re-iterating the entropy starvation issue and the un-willingness of systemd to fix its usage of randomness in early boot. Ahmed S. Darwish has reported the issue leading to ext4 reproducibly blocking boot with Kernel 5.3-r8. There are a few patches floated and the whole discussion it worth reading albeit non-conclusive as of now.

Ted Ts'o says "I really very strongly believe that the idea of making getrandom(2) non-blocking and to blindly assume that we can load up the buffer with 'best efforts' randomness to be a terrible, terrible idea that is going to cause major security problems that we will potentially regret very badly. Linus Torvalds believes I am an incompetent systems designer." in this email.

In case you needed a teaser to really start reading the thread! Linus Torvalds also mentions the issue (and a primer on what "never break userspace" means) in the Linux kernel 5.3 release notes.

18.09.2019

... and Martin Steigerwald kindly noticed that I update this blog post with the relevant discussions I come across as this entropy starvation mess continues to haunt us.

25.11.2019

Added the "Linus to the rescue" section after the Linux kernel 5.4 has been released.

02.04.2020

I ran into the same issue on a Gentoo system today. Luckily OpenRC handeled this gracefully but it delayed booting: syslog-ng actually hangs the boot for some time ... waiting for entropy. Argh. The Gentoo forums thread on the topic clearly listed the options:

  1. Make syslog-ng depend on haveged by adding rc_syslog_ng_need="haveged" to /etc/rc.conf (and obviously having haveged installed)
  2. Re-compiling the kernel with CONFIG_RANDOM_TRUST_CPU=y where that is an option

  1. it will return with EAGAIN in the GRND_NONBLOCK use case. The blocking behaviour when lacking entropy is a security measure as per Bug #1559 of Google's Project Zero

  2. Update 18.12.2018: "SysVinit times" ::= "The times when most Linux distros used SysVinit over other init systems." So Wheezy and previous for Debian. Some people objected to the statement, so I added this footnote as a clarification. See the discussion in the comments below. 

  3. there is no Buster branch in the release notes repository yet (17.12.2018). Update: I wrote a section for the release notes 06.05.2019 and Paul Gevers amended and committed that. So when users of affected systems read the release notes before upgrading to Buster they will hopefully not be surprised (and worried) by the long boot delays. 

Firefox asking to be made the default browser again and again

Linux

Firefox on Linux can develop the habit to (rather randomly) ask again and again to be made the default browser. E.g. when started from Thunderbird by clicking a link it asks but when starting from a shell all is fine.

The reason to this is often two (or more) .desktop entries competing with each other.

So, walkthrough: (GOTO 10 in case you are sure to have all the basics right)

update-alternatives --display x-www-browser
update-alternatives --display gnome-www-browser

should both show firefox for you. If not

update-alternatives --config <entry>

the entry to fix the preference on /usr/bin/firefox.

Check (where available)

exo-preferred-applications

that the "Internet Browser" is "Firefox".

Check (where available)

xfce4-mime-settings

that anything containing "html" points to Firefox (or is left at a non-user set default).

Check (where available)

xdg-settings get default-web-browser

that you get firefox.desktop. If not run

xdg-settings check default-web-browser firefox.desktop

If you are running Gnome, check

xdg-settings get default-url-scheme-handler http

and the same for https.

LABEL 10:

Run

sensible-editor ~/.config/mimeapps.list

and remove all entries that contain something like userapp-Firefox-<random>.desktop.

Run

find ~/.local/share/applications -iname "userapp-firefox*.desktop"

and delete these files or move them away.

Done.

Once you have it working again consider disabling the option for Firefox to check whether it is the default browser. Because it will otherwise create those pesky userapp-Firefox-<random>.desktop files again.

Configuring Linux is easy, innit?

Unbalanced volume (channels) on headset audio

Linux

I use a headset to make phone calls and when they are mono the great awesomeness of the Linux audio stack seems to change volume only on the active channel (e.g. the right channel). So when I listen to some music (stereo) afterwards the channels are not balanced anymore and one side is louder than the other. And this persists thanks to saving the preferences across reboots. Duh.

As usually checking Pulseaudio (pavucontrol) is useless, it shows balanced channels.

But checking Alsa (alsamixer) revealed the issue and alsamixer can fix this, too:

Step 1: run alsamixer in a terminal and select your headset after pressing [F6]:

Alsamixer: Select sound card

Step 2: Select the headset audio output with [<-] and [->] cursor keys:

Alsamixer: Unbalanced channels on the headset (left / right channel loudness are different)

Step 3: Press [b] to balance the left and right channels:

Alsamixer: Balanced channels (left / right channel loudness) again

Step 4: Press [Esc] to exit alsamixer which will keep the changed settings (... great choice of key, [q] raises the left channel's loundness ...).

Step 5: Save this setting by running sudo alsactl store which should update /var/lib/alsa/asound.state with the fixed settings so they persist across reboots.

Step 6: Enjoy music again :-).

If you need to script this, amixer is the tool to use, e.g. amixer -c 1 set "Headset" 36.
1 is the card number which you see in alsamixer, "Headset" is the channel name, also from alsamixer (which can contain blanks, hence the quotes around the name) and 36 is the desired loundness level for both channels. See the screenshots above where to find the data or run aplay -l to see the cards on your PC and amixer -c 1 (with your card id) to see the channels that (virtual, USB) sound card has.

Debian Gitlab (salsa.debian.org) tricks

Debian

Debian is moving the git hosting from alioth.debian.org, an instance of Fusionforge, to salsa.debian.org which is a Gitlab instance.

There is some background reading available on https://wiki.debian.org/Salsa/. This also has pointers to an import script to ease migration for people that move repositories. It's definitely worth hanging out in #alioth on oftc, too, to learn more about salsa / gitlab in case you have a persistent irc connection.

As of now() salsa has 15,320 projects, 2,655 users in 298 groups.
Alioth has 29,590 git repositories (which is roughly equivalent to a project in Gitlab), 30,498 users in 1,154 projects (which is roughly equivalent a group in Gitlab).

So we currently have 50% of the git repositories migrated. One month after leaving beta. This is very impressive.
As Alioth has naturally accumulated some cruft, Alexander Wirt (formorer) estimates that 80% of the repositories in use have already been migrated.

So it's time to update your local .git/config URLs!

Mehdi Dogguy has written nice scripts to ease handling salsa / gitlab via the (extensive and very well documented) API. Among them is list_projects that gets you nice overview of the projects in a specific group. This is especially true for the "Debian" group that contains the former collab-maint repositories, so source code that can and shall be maintained by Debian Developers collectively.

Finding migrated repositories

Salsa can search quite quickly via the Web UI: https://salsa.debian.org/search?utf8=✓&search=htop

Salsa search screenshot

but finding the URL to clone the repository from is more clicks and ~4MB of data each time (yeah, the modern web), so

$ curl --silent https://salsa.debian.org/api/v4/projects?search="htop" | jq .
[
  {
    "id": 9546,
    "description": "interactive processes viewer",
    "name": "htop",
    "name_with_namespace": "Debian / htop",
    "path": "htop",
    "path_with_namespace": "debian/htop",
    "created_at": "2018-02-05T12:44:35.017Z",
    "default_branch": "master",
    "tag_list": [],
    "ssh_url_to_repo": "git@salsa.debian.org:debian/htop.git",
    "http_url_to_repo": "https://salsa.debian.org/debian/htop.git",
    "web_url": "https://salsa.debian.org/debian/htop",
    "avatar_url": null,
    "star_count": 0,
    "forks_count": 0,
    "last_activity_at": "2018-02-17T18:23:05.550Z"
  }
]

is a bit nicer.

Please notice the git url format is a bit odd, it's either
git@salsa.debian.org:debian/htop.git or
ssh://git@salsa.debian.org/debian/htop.git.

Notice the ":" -> "/" after the hostname. Bit me once.

Finding repositories to update

At this time I found it useful to check which of the repositories I have cloned had not yet been updated in the local .git/config:

find ~/debconf ~/my_sources ~/shared -ipath '*.git/config' -exec grep -H 'url.*git\.debian' '{}' \;

Thanks to Jörg Jaspert (Ganneff) the Debconf repositories have all been moved to Salsa now.
Hint: Bug him for his scripts if you need to do complex moves.

Updating the URLs has been an hours work on my side and there is little you can do to speed that up if - as in the Debconf case - teams have used the opportunity to clean up and things are not as easy as using sed -i.

But there is no reason to do this more than once, so for the laptops...

Speeding up migration on multiple devices

rsync -armuvz --existing --include="*/" --include=".git/config" --exclude="*" ~/debconf/ laptop:debconf/

will rsync the .git/config files that you changed to other systems where you keep partial copies.

On these a simple git pull to get up to remote HEAD or using the git_pull_all one-liner from https://daniel-lange.com/archives/99-Managing-a-project-consisting-of-multiple-git-repositories.html will suffice.

Git short URL

Stefano Rivera (tumbleweed) shared this clever trick:

git config --global url."ssh://git@salsa.debian.org/".insteadOf salsa:

This way you can git clone salsa:debian/htop.

IMAPFilter 2.6.11-1 backport for Debian Jessie AMD64 available

Debian

One of the perks you get as a Debian Developer is a @debian.org email address. And because Debian is old and the Internet used to be a friendly place this email address is plastered all over the Internet. So you get email spam, a lot of spam.

I'm using a combination of server and client site filtering to keep spam at bay. Unfortunately the IMAPFilter version in Debian Jessie doesn't even support "dry run" (-n) which is not so cool when developing complex filter rules. So I backported the latest (sid) version and agreed with Sylvestre Ledru, one of its maintainers, to share it here and see whether making an official backport is worth it. It's a straight recompile so no magic and no source code or packaging changes required.

Get it while its hot:

imapfilter_2.6.11-1~bpo8+1_amd64.deb (IMAPFilter Jessie backport)
SHA1: bedb9c39e576a58acaf41395e667c84a1b400776

Clever LUA snippets for ~/.imapfilter/config.lua appreciated.

tail -S (truncating lines to terminal width)

Open Source

The tail command has a quite glaring omission in that it can't truncate lines. Thus it wraps long log line into multiple terminal lines regardless. Which makes them very hard to read.

I used to work around this using less -S and then hitting the [F] key but that's interactive. less +F <filename> is the little known work-around for the interactive issue but that still doesn't work well with pipes (tail -f logfile | grep "ERROR:" etc).

There is a bug report from 2004 against GNU coreutils but that went nowhere.

So we're not getting a tail -S anytime soon.

Bash to the rescue: tail -S → tails

Hence I wrote this little script, tails [1kB]:

  1. #!/bin/bash -i
  2. # v2 from 170712: introduce loop to work around GNU coreutils issues with pipe/fifo/isatty
  3.  
  4. if [[ -z "$COLUMNS" ]] ; then
  5.         MYCOL=$(tput cols)
  6. else
  7.         MYCOL=${COLUMNS}
  8. fi
  9. tail "$@" | while read line; do
  10.         echo "$line" | expand | cut -c1-${MYCOL:-80}
  11. done

Now, there are some interesting bits even in this tiny script:

The bash -i results in $COLUMNS being set within the script on sane Linux bash. Otherwise that variable wouldn't be available. Because it is a shell variable and not an environment variable. You knew that, right?

Unfortunately the bash -i doesn't get $COLUMNS set on either MacOS (X) or FreeBSD, so that's where the tput cols comes into play. It outputs the column width for the current terminal to stdout.

If all that fails tails will default to 80 columns.

So tails -f /var/log/apache/access.log will now look nice.

Corner case: color

If you use color codes somewhere (grep --color=always, dmesg --color=always) tails will just truncate lines too short so they will still not wrap.
There is a slight risk that it may cut into half a color code escape sequence and mess up the terminal a bit. You could change that by removing the -i from the shebang line and setting $COLUMNS explicitly. But that then needs manual adjustment for each combination of colored lines (=count of ANSI sequences) and terminal width. Better to color after the tails invocation then where possible, e.g. tails -f /var/log/httpd/error.log | grep ':error' to watch for PHP errors and the like.

Mended corner cases: inconsistent tail behaviour

A first version of the script didn't use a loop but just had

tail "$@" | expand | cut -c1-${MYCOL:-80}

This would break tails -f on Debian (coreutils 8.23) / Ubuntu (coreutils 8.26) while removing the |expand would make it work. On Fedora 25 (coreutils 8.25) I couldn't get tails -f to work at all with that v1. The cut (so just a single command chained) already broke the pipe :-(. And nope, stdbuf didn't help.

If you have a more simple solution to work around the isatty / isfifo mess, please leave a comment!

Alternatives

If you want to show multiple log tails in parallel, highlight strings etc. multitail is worth a look.

Depending on what you want to achieve you could also tell your terminal emulator to not wrap lines:

setterm -linewrap off; less -SR +F /var/log/apache/access.log; setterm -linewrap on

Prevent Ubuntu from phoning home

Linux

Ubuntu unfortunately has decided again to implement another "phone home" feature, this time transferring your lsb_release information, CPU model and speed (from /proc/cpuinfo), uptime output, most of uname -a and curl version to a Ubuntu news web-service.

Here is the Launchpad bug report #1637800 introducing this ... web bug.

This thing runs both systemd-timer based (via /lib/systemd/system/motd-news.service and /lib/systemd/system/motd-news.timer) and on request when you log in (via /etc/update-motd.d/50-motd-news).

Ubuntu news on ssh login

There has even been a bug filed about the motd advertising HBO's Silicon Valley show.

To prevent this from running (it is enabled by default on Ubuntu 17.04 and may probably propagate down to earlier versions as well), edit /etc/default/motd-news to include

ENABLED=0

so

sed -i "s/ENABLED=1/ENABLED=0/" /etc/default/motd-news # run as root

for your automated installs.

Update:

02.07.2017: Dustin Kirkland responded to a YC "hacker news" mention of his motd spam. He mentions:

You're welcome to propose your own messages for merging, if you have a well formatted, informative message for Ubuntu users.
We'll be happy to review and include them in the future.

What could possibly go wrong?

Thunderbird startup hang (hint: Add-Ons)

Debian

If you see Thunderbird hanging during startup for a minute and then continuing to load fine, you are probably running into an issue similar to what I saw when Debian migrated Icedove back to the "official" Mozilla Thunderbird branding and changed ~/.icedove to ~/.thunderbird in the process (one symlinked to the other).

Looking at the console log (=start Thunderbird from a terminal so you see its messages), I got:

console.log: foxclocks.bootstrap._loadIntoWindow(): got xul-overlay-merged - waiting for overlay-loaded
[.. one minute delay ..]
console.log: foxclocks.bootstrap._windowListener(): got window load chrome://global/content/commonDialog.xul

Stracing confirms it hangs because Thunderbird loops waiting for a FUTEX until that apparently gets kicked by a XUL core timeout.
(Thanks for defensive programming folks!)

So in my case uninstalling the Add-On Foxclocks easily solved the problem.

I assume other Thunderbird Add-Ons may cause the same issue, hence the more generic description above.

Saving misc/jive

BSD

One thing I love about FreeBSD is the way the core team keeps the wider community updated about project news e.g. via their quarterly status reports. So while reading the FreeBSD Q4/2016 status report, I was quite surprised to find that a text filter converting English to "Jive speak" had been removed from the ports tree. FreeBSD Core members argue that "today the implicit approval implied by having it in the ports tree sends a message at odds with the project's aims."

Now this is bullshit as I'm sure FreeBSD core neither endorses Citrix (net/citrix_ica) nor Cisco (emulators/gna3, devel/libcli, graphics/py27-blockdiagcontrib-cisco and many more) but just hosts code to make living with them easier.

So the important thing here is:

Important: Switch on brain and try to memorize. Hosting is not endorsing.
It is a purely technical act and by definition agnostic to the hosted content.

In every sane jurisdiction there is the requirement to remove hosted content that violates a law. And that makes sense. It reflects the societal consensus what is still acceptable and what is not. This changes over time but there is a proven process in place for these changes to become relevant: political discussion and consequential law making.

There is very deliberately never a law against bad taste and/or offensive humor. Where such a law still exists, you're in a somewhat underdeveloped jurisdiction. Because the hosting (pun intended) society has not matured sufficiently yet. This may happen due to overly conservative or self-protective ruling classes, ideological or religious blindness. None of these are desirable for society as a whole and the scissors in your head are paving the way to go back to darker ages. So don't. Be welcoming, be tolerant.

Tolerance means accepting things you do not like. Not accepting just what endorses your personal taste, beliefs or state of mind.

Does that mean, FreeBSD should continue to host the "Jive" filter? No, it's purely their choice. But their argument that hosting is endorsing is wrong. Inclusion into a FreeBSD media may be, like Debian strictly differentiates between the main archive, which it endorses, and contrib or non-free sections which it does not endorse. But still hosts regardless. So hosting is not endorsing.

That said, here you go:

File Function sha256
jive-1.1.tar.gz Source to the "Jive" filter 3463d80ad159a27d9fcf87f163a7be5eba39dbf15c5156f052798b81271523f2
ports_misc_jive.tar.gz ports files to build the "Jive" filter under FreeBSD 47dc7b660d499d671daa18f992cdd348bd95c34e02874addd2bcf3e5c3f90b59
swedishchef.zip mirror of swedishchef.zip d0830b81aec6ad6a6ff824e1d80c9fa97d3a5447bad9f8a2b32dbd0dfb8df709

The last file above is a mirror of files hosted by John B. Chambers. He has a "chef" cgi running there allowing the conversion of English text to "Swedish Chef", "Valley Girl" or "Pig Latin". And the "Jive" variant that uses the same Lex/Yacc/Flex files as the misc/jive that used to be part of the FreeBSD ports tree and is conserved above.

If you are interested in the public part of the discussion that happened after misc/jive was marked for removal from the ports tree, check out the freebsd-ports mailing list thread.

P.S.: Valspeak is still in the ports tree as misc/valspeak ... just sayin'.

P.P.S.: apt-cache show filters # Debian & Ubuntu. Awesome. ♡

Mozilla Firefox and Thunderbird Menu font sizes

Open Source

The font size Mozilla chose for Firefox and Thunderbird menus looks awfully large on Netbook screens. It wastes space and is visually at odds with reasonably sized content. And for some weird reason you can set the content font and size via the menu but not the font and size for the drop-down menus themselves.

As the "Theme Font & Size Changer" Add-On doesn't work reliably and phones home way too often (showing a nag screen), I dug back into how to do this "manually". Probably a decade after I fixed this the first time...

You need to create the file ~/.mozilla/firefox/*/chrome/userChrome.css with * being your profile directory (<random_number>.default usually) and you most probably have to create the chrome directory first.

The same for Thunderbird resides in ~/.thunderbird/*/chrome/userChrome.css. Here again the chrome directory will most probably need to be created first.


/* Global UI font */
* { font-size: 10pt !important;
  font-family: Ubuntu !important;
}
 

needs to go into these files for Firefox or Thunderbird respectively. The curly braces are important. So copy & paste correctly. Symlinks or hardlinks are fine if those files do not need to differ between your web browser and your email client.

Restart Firefox and/or Thunderbird to see the effect.

Obviously you can choose any other font and font size in the snippet above to suit your taste and requirements.

If you are massively space-confined and don't mind a quite ugly UI, check out the Littlefox Add-on. Ugly but optimal use of the minimal screen estate with very small screens.

Netatalk 3.1.9 .debs for Debian Jessie available (Apple Timemachine backup to Linux servers)

Debian

Netatalk 3.1.9 has been released with two interesting fixes / amendments:

  • FIX: afpd: fix "admin group" option
  • NEW: afpd: new options "force user" and "force group"

Here are the full release notes for 3.1.9 for your reading pleasure.

Due to upstream now differentiating between SysVinit and systemd packages I've followed that for simplicity's sake and built libgcrypt-only builds. If you need the openssl-based tools continue to use the 3.1.8 openssl build until you have finished your migration to a safer password storage.

Warning: Read the original blog post before installing for the first time. Be sure to read the original blog post if you are new to Netatalk3 on Debian Jessie!
You'll get nowhere if you install the .debs below and don't know about the upgrade path. So RTFA.

Now with that out of the way:

Continue reading "Netatalk 3.1.9 .debs for Debian Jessie available (Apple Timemachine backup to Linux servers)"

Irssi update to 0.8.19 from Debian jessie-backports may break enter / carriage return key / ↵ key

Debian

Updating to irssi 0.8.19 (which is a mainly a bugfix release to 0.8.18) proved a real issue. The enter key (return key) stopped working. Ctrl-J still worked but that's way too annoying to remember after each line. Searching the github issues turned up #327 Numeric keypad "Enter" key stopped working which didn't help much. Digging deeper it shows the irssi devs enabled "App key" mode in these releases which causes so many issues, they had to implement a switch to turn it off again.

So a hopeful: /set term_appkey_mode off followed by Ctrl+J, remember ...

and ... nothing changed.

So finally, after more digging and a quick consideration to go back to irssi 0.8.17 on Debian stable (Jessie) ...

/bind ^M key return

Yes, irssi 0.8.19 wants to be told what the enter key is, like, by default. Duh.
No idea what caused this in my configuration, I've been using irssi for more than a decade so much cruft has accumulated in my .irssi/config but ... in case you run into this as well, hopefully I helped you save a morning for something better to do.

If you want to fumble this into your .irssi/config (e.g. because Ctrl-J does not work for you):

keyboard = (
  [...]
  { key = "^M"; id = "key"; data = "return"; },
  [...]
);

Dovecot segfaulting (Ubuntu 14.04 LTS, CentOS 6 and 7)

Open Source

We're currently installing a solution including dovecot for a company to go into production in April. So we kick this off with a development box for integrating parts that different suppliers to our customer are working on.

But after installing dovecot on the new joint development machine it just didn't start. It worked on our local development boxes but the install for the customer has been scripted with (what we call) "poor man's puppet" so it is somewhat hard to compare the setups. Same Ubuntu 14.04 LTS under the hood but on top of that things (like config layout, directory structures etc.) are quite different.

Back on topic: ps aux | grep d[o]ve returned empty.

Looking at /var/log/mail.log did not show anything relevant.

But syslog (/var/log/syslog) had some worrying lines like:

Mar 16 03:16:17 dev-new kernel: [ 3222.339365] doveconf[6420]: segfault at 200 ip 00007fa041b25a03 sp 00007ffe7881e070 error 4 in libc-2.19.so[7fa041ada000+1bb000]

Manually running the daemon resulted in:

# /usr/sbin/dovecot -F -c /etc/dovecot/dovecot.conf
Segmentation fault

So

mkdir /var/core
chmod 1777 /var/core
echo "/var/core/%p" > /proc/sys/kernel/core_pattern
ulimit -c unlimited
/usr/sbin/dovecot -F -c /etc/dovecot/dovecot.conf
Segmentation fault (core dumped)

Better. We have a core file now.

But:

Continue reading "Dovecot segfaulting (Ubuntu 14.04 LTS, CentOS 6 and 7)"

Netatalk 3.1.8 .debs for Debian Jessie available (Apple Timemachine backup to Linux servers)

Debian

The Debian Netatalk3 saga continues at bug #685878. In season 4 of the epic the main issue still seems to be unclear license indications of a (very) few source files. And the usual "you go fix it", "no! you go fix it!". May be the fact that Firefox will be Firefox again in Debian [yeah!] could serve as an inspiration to the Netatalk maintainers?

Ah, well, until we have the eureka moment for Netatalk3 (4?) ...
<pragmatism style="priority-on-users:yes"> ... I'll post my .debs of the new 3.1.8 version of Netatalk as well.

Warning: Read the original blog post before installing for the first time. Be sure to read the original blog post if you are new to Netatalk3 on Debian Jessie!
You'll get nowhere if you install the .debs below and don't know about the upgrade path. So RTFA.

The release notes for 3.1.8 don't list anything that makes the update look mandatory but there is a nice compatibility fix for shares also exported via Samba (compatible xattrs handling). And it's faster.

The update instructions (assuming you have installed 3.1.7 before) are:

# install new debs
dpkg -i libatalk17_3.1.8-1_amd64.deb netatalk_3.1.8-1_amd64.deb
# reboot the box (restart of netatalk may not be sufficient)
reboot
# After reboot: remove the obsolete libatalk16 (3.1.8 uses libatalk17)
dpkg -r libatalk16

And here are the files:

Continue reading "Netatalk 3.1.8 .debs for Debian Jessie available (Apple Timemachine backup to Linux servers)"

Apple Timemachine backups on Debian 8 (Jessie)

Debian

Upgrading Debian 7 (Wheezy) servers to Debian 8 (Jessie) proves (unexpectedly) quite rough around the edges.

That's what you get for using a version x.0, we should have known better :-).

And - of course - the release notes follow the common practice of not even mentioning any of the issues we encountered so far.

Ah, well, let's go through the first one:

In Debian 7 (Wheezy) there was netatalk 2.2.2 (packages link). Now during upgrades that package may or may not get removed. There is no netatalk in Debian 8 (Jessie) anymore. Duh. There is in sid (aka Debian unstable) (packages link) so we may see a backport some time. Or not. In any case this is still 2.2.5 at the time of writing and as Adrian Knoth put it in the three year old bug asking for a upgrade to Netatalk 3:

Let's not ship another release without netatalk3, it's embarrassing.

Yes. It is. Removing a working version and not even mentioning it in the release notes is even worse though. So no cookies there.

Luckily the absolutely awesome Debian and greater FLOSS community have sorted 90% of the problem out for us already:

A quick Google search turns up an excellent article on netatalk's wiki that details installing Netatalk 3.1.7 on Debian 8 Jessie. There are two shortcomings to this: First it doesn't compile to .debs but installs besides apt and friends. And second it compiles with Spotlight search, courtesy of Gnome tracker, which doesn't really work well on servers yet. Hence we're lucky that Adrian Knoth's debified install has not yet added the tracker dependencies. It does compile for systemd use (the default for Debian 8 Jessie). If you want to continue using SysVInit, you need to modify debian/rules.

Compiling to .debs becomes as easy as:

# get build dependencies and a few helpers
apt-get install build-essential devscripts debhelper cdbs autotools-dev dh-buildinfo libdb-dev libwrap0-dev libpam0g-dev libcups2-dev libkrb5-dev libltdl3-dev libgcrypt11-dev libcrack2-dev libavahi-client-dev libldap2-dev libacl1-dev libevent-dev d-shlibs dh-systemd
# in case you want to try the tracker support (you need to ammend the debian/ build config as well)
# apt-get install tracker libtracker-sparql-1.0-dev libtracker-miner-1.0-dev  
git clone https://github.com/adiknoth/netatalk-debian
cd netatalk-debian
debuild -b -uc -us

This should leave you with (at the time of writing this):

File Function md5 sha1
libatalk-dev_3.1.7-1_amd64.deb Development files for the libatalk library (dev only) e5a465e39a8560c919d8db85c8e5a83b 0b924cf75f22ab42406289c6f18ae0243d6396a3
libatalk16_3.1.7-1_amd64.deb libatalk library (needed) 17a3d677ed0b3df1c2f4c1a8ab9045fd 7345ed3edd442716c99c2fe979140703204c0826
netatalk_3.1.7-1_amd64.deb netatalk daemons (needed) c694abca7f3cdc0070b2b3e7d528324a 932d1e3d5899958f29e79a7ba40e858d4ac272e8

Obviously you can download the files above if you run the AMD64 architecture and trust me enough to compile them for you.

Continue reading "Apple Timemachine backups on Debian 8 (Jessie)"