Snom VoIP phones: OpenVPN and multicast audio

Snom voice-over-IP phones have a built-in OpenVPN client, and they can also have audio transmitted to them via multicast. However, in my case a phone logged into OpenVPN did not play back audio received from the local ethernet network

I had multicast reception configured correctly on the phone:

multicast_listen=on
mc_address=239.255.255.245:5555

(Remember that you need to push the Apply button at the bottom of the page and then the Save button at the top of the page for the setting to actually take effect.)

To diagnose the problem, you can use multicast pings. Running

ping -I eth0 -t 2 239.255.255.245

on the local network showed no reactions from the phone. However, running

ping -I tun2 -t 2 239.255.255.245

on the VPN server showed responses from the phone. So clearly the phone wanted to do multicast exclusively via VPN. The cause of this was the following line in my OpenVPN config on the server:

push "redirect-gateway def1"

The obvious solution was to replace this line with routes that excluded the multicast IP addresses:

push "route 0.0.0.0 128.0.0.0"
push "route 128.0.0.0 192.0.0.0"
push "route 192.0.0.0 224.0.0.0"

While this worked, the phone wouldn’t complete booting up the next time I power-cycled it. So I switched back to the old OpenVPN config and instead turned on multicast routing on the VPN server:

apt-get install smcroute
echo 'mgroup from eth0 group 239.255.255.245' > /etc/smcroute.conf
echo 'mroute from eth0 group 239.255.255.245 to tun0 tun1 tun2' > /etc/smcroute.conf
service smcroute restart

Multicast audio now works and it even goes across the VPN.

Below you can find some commands that use FFMPEG to send the multicast audio:

ffmpeg -re -i song.mp3 -filter_complex 'aresample=16000,asetnsamples=n=160' -acodec g722 -ac 1 -vn -f rtp udp://239.255.255.245:5555
ffmpeg -re -i song.mp3 -filter_complex 'aresample=8000,asetnsamples=n=160' -acodec pcm_mulaw -ac 1 -vn -f rtp udp://239.255.255.245:5555
ffmpeg -re -i song.mp3 -filter_complex 'aresample=8000,asetnsamples=n=160' -acodec pcm_alaw -ac 1 -vn -f rtp udp://239.255.255.245:5555

Interestingly, you don’t even need to set the rtp_codec_type setting — the phone automatically determines the codec from the stream. I wasn’t able to get the Opus codec working though, the phone just makes crackling noises when I tried.

OpenMPI and SLURM CPU pinning

The SLURM scheduling and queueing system pins processes to CPUs. This worked great with OpenMPI 1.6, but OpenMPI 1.8 introduced its own pinning policy. As a result, our jobs ended up running very slowly because all jobs that used less than a whole machine ended up getting pinned to cores 0 through n, where n is the number of cores requested by a job.

Fixing this is pretty simple: just disable OpenMPI’s pinning so that the MPI processes inherit the scheduler’s pinning. To do that, add the following to your job script:

export OMPI_MCA_hwloc_base_binding_policy=none

Obviously, as a more permanent and more fool-proof solution, set that setting in the OpenMPI config file on all of your compute nodes, have the scheduler set that environment variable, or put it into your module file for OpenMPI.

Leserbrief “Bargeld”

Im Februar 2015 forderten eine Reihe von Politikern, Bargeld-Transaktionen oberhalb von 5000 Euro zu verbieten, um Geldwäsche und Finanzierung krimineller Aktivitäten zu verhindern. Um auf die Probleme verdachtsunabhängiger Datenspeicherung hinzuweisen, verfasste ich einen Leserbrief, den die Süddeutsche Zeitung am 15. Februar 2016 abdruckte:

Weiterer Baustein

[Wie bei der Vorratsdatenspeicherung für Telekommunikation belegen Studien auch der Einschränkung des anonymen Bargeldverkehrs keinen nennenswerten Nutzen für die Verhinderung von Straftaten.] Auch das organisierte Verbrechen arbeitet heute weitgehend bargeldlos. Beim Bargeld dürfte die Obergrenze nur ein erster Schritt zur vollständigen Abschaffung sein, ein weiterer Baustein der umfassenden Überwachung aller Bürger.
Datensammlungen durch und für den Staat sind grundsätzlich kritisch zu sehen: wer weiß schon, was eine Regierung in 15 Jahren mit den heute festgehaltenen Daten anstellt? [Als dystopische Beispiel sei an die Volkszählung 1930 in den Niederlanden erinnert: sie erfolgte erstmalig auf Lochkarten, weshalb die Deutschen 11 Jahre später den Lochkartensortierer nur auf die “Religionszugehörigkeit”-Spalte einstellen mussten, um systematisch mit ihren grausamen Taten zu beginnen.]

Michael Kuron, Frickenhausen

Der erste und letzte Satz sind leider der redaktionellen Kürzung zum Opfer gefallen, wofür ich Verständnis habe. Dennoch möchte ich sie hier samt Quellen erwähnen.

Triple-booting a Clamshell iBook

I have a first-generation Clamshell iBook, manufactured in January 2000. These shipped with 64 MB of on-board RAM, a 6 GB hard drive and a CD drive.
I got it in summer 2005 when my high school decommissioned these computers. Running Mac OS X 10.3.9 at the time, it was still a very usable computer, especially after I upgraded the RAM to 320 MB. I used it as my main computer for a year and a half, until I replaced it with a new Intel-based Mac.

Now, in 2016, I found a 40 GB IDE laptop hard drive and decided to put that into the Clamshell and try to make it usable again.
As usual, iFixit has a good tutorial. You have to take the entire machine apart and end up with around 50 screws, but it’s surprisingly easy. You only need a Torx T8, a Philips #1 and a 5mm nut driver.
Now, on to putting some operating systems on the hard drive.

Installing Mac OS X 10.4

Here is what you need:

  • Mac OS X 10.4 retail install DVD
  • Mac OS X 10.3 retail install CD (the first one is sufficient). Any other bootable Mac OS X 10.3 CD might also work.
  • USB hard drive

Officially, Tiger is only supported on the latest revision of the Clamshell iBook, which has FireWire and a DVD drive. Mine only has a CD drive and does not support USB booting, which makes things exceedingly difficult.

  1. Take an image of the 10.4 install DVD and save it onto the USB hard drive using a different Mac.
  2. Boot the Clamshell off the 10.3 install CD
  3. Open up Disk Utility. Partition the disk with the following sizes and names: 16 MB linux-boot, 2 GB linux-swap, 12 GB linux, 20 GB Macintosh HD, 6 GB Install. Make sure to select the Install OS 9 drivers checkbox.
  4. Plug in the USB hard drive.
  5. Clone the 10.4 install image onto the Install partition on the internal drive.
  6. Open a Terminal and bless the hard drive: bless --folder "/Volumes/Install/System/Library/CoreServices" --bootinfo "/Volumes/Install/usr/standalone/ppc/bootx.bootinfo".
  7. Using the Terminal, pico /Volumes/Install/System/Installation/Packages/OSInstall.mpkg/Contents/OSInstall.dist and remove the PowerBook2,1 from the badMachines list.
  8. Open Startup Disk and set the iBook to boot from the Install partition.
  9. Reboot
  10. Install 10.4 onto the Macintosh HD partition, deselecting all printer drivers and languages you don’t need in order to save some space.
  11. After the reboot, run Software Update a few times.

Installing Mac OS 9.2.2

Here is what you need:

Mac OS 9 is really easy to install, you just copy it to the hard drive.

  1. Mount the CD or image and copy System Folder and Applications (Mac OS 9) from the root directory to your Macintosh HD.
  2. Open the Startup Disk preference pane and select Mac OS 9.2.2.
  3. Reboot.
  4. If you used the NetBoot image, you will be asked for user name and password. Use NBUser and netboot.
  5. In order to disable the password prompt, go to the hard drive, System Folder and move the contents of Control Panels disabled to Control Panels. Now open the Multiple Users control panel, go to options and set it to local authentication. Then, disable multiple users entirely.
  6. Download and install QuickTime 6.0.3 for Mac.
  7. Open the Startup Disk control panel and select Mac OS 10.4.
  8. After the reboot, open the Classic preference pane and select the system folder on Macintosh HD.

Now you can use Classic and you can also do a native boot.

Installing Debian Linux 8 “Jessie”

Mac OS 9.2.2 hasn’t received updates in almost 15 years, and Mac OS X 10.4 is also 7 years beyond its update cycle. So how about a current operating system?

Here is what you need:

Except for the partitioning, the installation is quite straight-forward.

  1. Insert the CD and boot it by holding the C key while turning on the computer.
  2. Proceed through the installer.
  3. When asked for the partitioning, set the 16 MB partition to be NewWorld Boot and set the bootable flag. Set the 2 GB partition to be swap. Set the 12 GB partition to be ext3 and mounted at /.
  4. When asked for the packages to install, choose the Xfce desktop. It’s lightweight enough to run on this old hardware.
  5. After rebooting, run nano /etc/apt/sources.list and add the non-free repository to all entries in the file. Then, install the AirPort firmware: apt-get install linux-firmware-nonfree.

The resulting Debian install mostly worked for me, except for two things:

  • the AirPort card does not show up in NetworkManager
  • Fonts are a bit messed up. Bitmaps are drawn to the screen just fine.

I’m still looking for solutions to these two things.

Configuring the yaboot bootloader

Right now, your computer will boot into Linux all the time.
While the yaboot loader prompts you to hit x to boot into Mac OS X and m to boot into Mac OS 9, that doesn’t work as expected.
Instead of booting into Mac OS X, my iBook booted into the install partition.
And instead of booting into Mac OS 9, my iBook booted into Mac OS X.

So run nano /etc/yaboot.conf and adjust the macosx= line so that it refers to the same partition as the macos9= line. Exit the editor and run ybin -v to apply the changes. That fixes the first problem.

Now, reboot into Mac OS X and open the Startup Disk preference pane. Select Mac OS 9.2.2 and reboot.
While rebooting, hold down the option key and select the Linux partition at the boot picker.
Run nano /etc/yaboot.conf again and add brokenosx to a new line. Once more, run ybin -v.

Now, each boot loader entry does what you’d expect. The trick here is that brokenosx causes yaboot to directly load the Mac OS X booter for the macosx= entry. The macos= entry, on the other hand, will still cause the blessed system folder to be booted.

Fixing Mac OS 9 after installing Linux

One problem is still there: When you try to boot Mac OS 9, you are greeted by a blinking floppy with a question mark. This happens because the Debian partitioner destroys the Mac OS 9 drivers for the HFS+ partitions. However, the drivers can be reinstalled.

You need:

  • Mac OS 9 install CD. Any other bootable Mac OS 9 CD might also work.

Now,

  1. Insert the CD and reboot the iBook while holding down the C key.
  2. Open Drive Setup, highlight the internal hard drive, go to the Functions menu and click Update Drivers.
  3. Reboot

Resetting the Startup Disk

Whenever you touch the Startup Disk preference pane in Mac OS X or the Startup Disk control panel in Mac OS 9, your system will no longer show the yaboot prompt when you turn it on. To fix that, do the following:

  1. Hold down the option key while booting and select the Linux partition
  2. Run ybin -v

Fixing Linux problems

http://ppcluddite.blogspot.de/2012/03/installing-debian-linux-on-ppc-part-iv.html is an excellent article that explains how to fix most issues that Debian has on PowerPC. For example, to fix the font rendering troubles, create an xorg.conf file (switch to a text terminal, run init 3, Xorg -configure, cp /root/xorg.conf.new /etc/X11/xorg.conf) and insert Option "RenderAccel" "false" into its Device section.

Migrating JIRA to osTicket

We were running JIRA as a ticket system for tech support and as a knowledge base. While this works, it’s not ideal, so we’ve decided to switch to osTicket. Of course, we wanted to migrate all issues, comments, attachments and issue links. JIRA has a good REST API, and osTicket has a rather simple database schema, so I’ve created a PHP script to do the migration, which you can obtain at https://gist.github.com/mkuron/3e1c92f9c4e993c65857.

This script is not meant as a black-box solution. It can only get you started in creating your own migration script, as every JIRA setup is different. Before you start, create all staff accounts in osTicket and make sure they have the same user name as in JIRA. Then, set up OAuth for JIRA as explained here: Two-legged OAuth between PHP and JIRA. Add your MySQL password and the mail domain you use to identify staff accounts to the scripts (if you don’t have a common mail domain for staff accounts, you’ll need to edit the logic to identify staff accounts based on group membership). Specify your tech support project key and give the map of knowledge base project keys to osTicket KB category IDs. Run the scripts on the command-line and copy the resulting attachments folder to your osTicket server (note that you’ll need the Attachments on Filesystem plugin and configure it to use the attachments folder).

The scripts are rerun-safe and transactional. If you want, you can remove the jira_id columns from the ost_faq, ost_ticket_thread and ost_file tables after you finish the migration.

To ensure that links continue working as much as possible, add the following redirects to your web server config:

# Redirect JIRA issues
RedirectMatch permanent ^/jira/browse/(TECH-[0-9]+) /osticket/jira-redir.php?key=$1
# Redirect all other JIRA pages
RedirectMatch permanent ^/jira/ /osticket
# prevent access to attachments folder
RedirectMatch ^/osticket/attachments/ /osticket/file.php

Put the following file into your osTicket folder and call it jira-redir.php:

<?php
require_once 'bootstrap.php';
require_once INCLUDE_DIR . 'ost-config.php';
if (substr(DBHOST,0,1) == ':')
 $mysqli = new mysqli("localhost", DBUSER, DBPASS, DBNAME, 3306, substr(DBHOST, 1));
else
 $mysqli = new mysqli(DBHOST, DBUSER, DBPASS, DBNAME);

$stmt = $mysqli->prepare('SELECT ticket_id FROM ' . TABLE_PREFIX . 'ticket WHERE number=?');
$stmt->bind_param("s", $_GET['key']);
$stmt->execute();
$stmt->bind_result($ticket_id);
$stmt->fetch();
$stmt->close();

$url = 'http://';
if ($_SERVER['HTTPS'])
 $url = 'https://';
$url .= $_SERVER['HTTP_HOST'];
$url .= dirname($_SERVER['SCRIPT_NAME']);
$url .= '/scp/tickets.php?id=';
$url .= $ticket_id;
header("Location: " . $url, true, 301);
?>

Digest authentication freezes Apache on OS X Server 5.0

When running a web site on OS X Server 5.0 for a while (on OS X 10.10.5 in my case), eventually you’ll notice hundreds of httpd processes in Activity Monitor. One or two might cause a bit of CPU load, while the others don’t do anything. When you try to load the web page, it is insanely slow and often throws a HTTP 500 error, a HTTP 502 Proxy Error, or the connection just times out. /var/log/apache2/error_log reports errors like

[Thu Nov 05 13:15:24.435549 2015] [mpm_prefork:error] [pid 60920] AH00161: server reached MaxRequestWorkers setting, consider raising the MaxRequestWorkers setting.

but that’s the only hint you get. To find out more, add the following lines inside the VirtualHost section of /Library/Server/Web/Config/apache2/sites/0000_127.0.0.1_34580_.conf and restart the Websites service in Server.app:

<Location /server-status>
SetHandler server-status
</Location>

Now, got to http://localhost/server-status and refresh it occasionally while traffic hits your web site. You’ll eventually see dozens of lines like the one below (starting with 52-0 in my case):

Scoreboard Key:
"_" Waiting for Connection, "S" Starting up, "R" Reading Request,
"W" Sending Reply, "K" Keepalive (read), "D" DNS Lookup,
"C" Closing connection, "L" Logging, "G" Gracefully finishing,
"I" Idle cleanup of worker, "." Open slot with no current process
Srv PID Acc M   CPU SS  Req Conn    Child   Slot    Client  VHost   Request

52-0    80825   0/2/2   C   0.45    51  0   0.0 0.02    0.02    ::1

All httpd processes you’re seeing in Activity Monitor are stuck in “Closing connection”, except for those that cause considerable CPU load. If the server were behaving correctly, you wouldn’t have as many processes and those that aren’t currently handling requests would either be “Waiting for Connection” or “Open slot with no current process”.

Let’s fire up a debugger to see what’s causing the processes to get stuck:

$ sudo lldb -p 80825
(lldb) process attach --pid 80825
Process 80825 stopped
* thread #1: tid = 0x3a69d4, 0x00007fff8fe35902 libsystem_kernel.dylib`__wait4 + 10, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
    frame #0: 0x00007fff8fe35902 libsystem_kernel.dylib`__wait4 + 10
libsystem_kernel.dylib`__wait4:
->  0x7fff8fe35902 <+10>: jae    0x7fff8fe3590c            ; <+20>
    0x7fff8fe35904 <+12>: movq   %rax, %rdi
    0x7fff8fe35907 <+15>: jmp    0x7fff8fe30c78            ; cerror
    0x7fff8fe3590c <+20>: retq   

Executable module set to "/usr/sbin/httpd".
Architecture set to: x86_64-apple-macosx.
(lldb) bt
* thread #1: tid = 0x3a69d4, 0x00007fff8fe35902 libsystem_kernel.dylib`__wait4 + 10, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
  * frame #0: 0x00007fff8fe35902 libsystem_kernel.dylib`__wait4 + 10
    frame #1: 0x0000000109b3ee95 libapr-1.0.dylib`apr_proc_wait + 70
    frame #2: 0x000000010aa4290c mod_auth_digest_apple.so`cleanup_server_event + 73
    frame #3: 0x0000000109b3627a libapr-1.0.dylib`apr_pool_destroy + 82
    frame #4: 0x0000000109a74ce2 httpd`clean_child_exit + 50
    frame #5: 0x0000000109a74c59 httpd`child_main + 2393
    frame #6: 0x0000000109a73b2e httpd`make_child + 510
    frame #7: 0x0000000109a74181 httpd`perform_idle_server_maintenance + 1265
    frame #8: 0x0000000109a72887 httpd`prefork_run + 2471
    frame #9: 0x0000000109a26328 httpd`ap_run_mpm + 120
    frame #10: 0x0000000109a1185f httpd`main + 4687
    frame #11: 0x00007fff8d7435c9 libdyld.dylib`start + 1
(lldb) continue
Process 82070 resuming
(lldb) exit

Ah, so mod_auth_digest_apple.so is the culprit. So in all *.conf files in /Library/Server/Web/Config/apache2 and its subdirectories, replace every occurrence of AuthType Digest with AuthType Basic and comment out all lines containing mod_auth_digest_apple.so by prepending a # character. Restart the Websites service in Server.app. Watch http://localhost/server-status: everything should be fine now and no more connections stuck on “Closing connection”!

Printer Sharing randomly stops working due to memorystatus_thread killing cupsd

Printers shared in OS X 10.9, 10.10 or 10.11 randomly stop being accessible from remote computers. The system log reports that the cupsd process was terminated by memorystatus_thread:

Oct 26 07:14:33 robert kernel[0]: memorystatus_thread: idle exiting pid 4901 [cupsd]

This can also manually be triggered by executing sudo launchctl stop org.cups.cupsd.plist and manually and temporarily fixed by executing sudo launchctl start org.cups.cupsd.plist.

As a workaround, you can edit the CUPS LaunchDaemon to restart whenever a remote computer attempts to connect. On 10.9 or 10.10:

sudo /usr/libexec/PlistBuddy -c "Delete Sockets:Listeners:0:SockNodeName" /System/Library/LaunchDaemons/org.cups.cupsd.plist
sudo /usr/libexec/PlistBuddy -c "Delete Sockets:Listeners:1:SockNodeName" /System/Library/LaunchDaemons/org.cups.cupsd.plist
sudo launchctl unload /System/Library/LaunchDaemons/org.cups.cupsd.plist
sudo launchctl load /System/Library/LaunchDaemons/org.cups.cupsd.plist

On 10.11, first disable System Integrity Protection in Recovery mode, then run

sudo /usr/libexec/PlistBuddy -c "Add Sockets:Listeners:1 Dict" /System/Library/LaunchDaemons/org.cups.cupsd.plist/org.cups.cupsd.plist
sudo /usr/libexec/PlistBuddy -c "Add Sockets:Listeners:1:SockServiceName String" /System/Library/LaunchDaemons/org.cups.cupsd.plist/org.cups.cupsd.plist
sudo /usr/libexec/PlistBuddy -c "Set Sockets:Listeners:1:SockServiceName ipp "/System/Library/LaunchDaemons/org.cups.cupsd.plist/org.cups.cupsd.plist
sudo launchctl unload /System/Library/LaunchDaemons/org.cups.cupsd.plist
sudo launchctl load /System/Library/LaunchDaemons/org.cups.cupsd.plist

ARP and multicast packets lost with OpenVPN in tap mode

After upgrading our OpenVPN server VM from Debian 7 to Debian 8 (moving us from OpenVPN 2.2 to OpenVPN 2.3 and Linux kernel 3.2 to Linux kernel 3.16) and upgrading our virtualization from VMware ESXi 5.5 to ESXi 6.0 and moving the VM to a different host, the VPN got really unreliable: the VPN connection itself worked fine, but any connections established across the VPN were very slow to get established. Once they were established, everything worked fine and you could even create new connections to the same host across the VPN and they would be established quickly.

I wasn’t sure which one of the many changes caused the issue, but luckily Wireshark quickly revealed the problem: As we are using OpenVPN in layer 2 mode (i.e. with tap interfaces), ARP packets are quite important. While I could see the ARP requests making it across the interface bridge from tap0 to eth0, I saw the ARP replies going into eth0 and not making it to tap0. The server-side fix is easy, just disable the MAC table on the bridge completely and simply lets all packets pass:

brctl setageing br0 0

Now that ARP was working, I noticed that VPN clients also did not get IPv6 addresses. Evidently, the ICMPv6 multicasts weren’t making it across the bridge either. To fix that, enable multicast snooping on the bridge:

echo 1 > /sys/devices/virtual/net/br0/bridge/multicast_querier

Update March 2016: A recent kernel update in Debian Jessie appears to have changed the multicast bridging behavior. I now need to disable multicast snooping:

echo 0 > /sys/devices/virtual/net/br0/bridge/multicast_querier

Fixing OpenMPI over InfiniBand on Rocks Cluster Linux

We recently got a new small compute cluster at the university, running Rocks Clusters Linux 6.1.1, a CentOS 6 derivative. The nodes are interconnected via an InfiniBand network. Unfortunately, the default configuration of OpenMPI 1.6.2 in the HPC roll wastes a significant amount of performance: it communicates using TCP, which is run over a load-balanced combination of IP over InfiniBand and IP over Ethernet.

Switching to DMA over InfiniBand is simple: just run the following command on all compute nodes and the head node:

sed -i 's/add rocks-openmpi/add rocks-openmpi_ib/g' /etc/profile.d/rocks-hpc.*sh

Now however, you get a message like this when you run an MPI job:

--------------------------------------------------------------------------
WARNING: It appears that your OpenFabrics subsystem is configured to only
allow registering part of your physical memory.  This can cause MPI jobs to
run with erratic performance, hang, and/or crash.

This may be caused by your OpenFabrics vendor limiting the amount of
physical memory that can be registered.  You should investigate the
relevant Linux kernel module parameters that control how much physical
memory can be registered, and increase them to allow registering all
physical memory on your machine.

See this Open MPI FAQ item for more information on these Linux kernel module
parameters:

    http://www.open-mpi.org/faq/?category=openfabrics#ib-locked-pages

  Local host:              bee.icp.uni-stuttgart.de
  Registerable memory:     32768 MiB
  Total memory:            130967 MiB

Your MPI job will continue, but may be behave poorly and/or hang.
--------------------------------------------------------------------------

To fix that, run

echo "options mlx4_core log_num_mtt=24" >> /etc/modprobe.d/mlx4.conf

on all nodes and reboot. log_mtts_per_seg defaulted to 3 on our kernel and did not need tweaking. To check your current values, run

grep . /sys/module/mlx4_core/parameters/*mtt*

One warning message that still comes up when running an MPI job is the following:

--------------------------------------------------------------------------
WARNING: Failed to open "OpenIB-cma-1" [DAT_INVALID_ADDRESS:]. 
This may be a real error or it may be an invalid entry in the uDAPL
Registry which is contained in the dat.conf file. Contact your local
System Administrator to confirm the availability of the interfaces in
the dat.conf file.
--------------------------------------------------------------------------
bee.icp.uni-stuttgart.de:30104:  open_hca: getaddr_netdev ERROR: No such device. Is ib1 configured?
bee.icp.uni-stuttgart.de:30104:  open_hca: device mthca0 not found
bee.icp.uni-stuttgart.de:30104:  open_hca: device mthca0 not found
DAT: library load failure: libdaplscm.so.2: cannot open shared object file: No such file or directory
DAT: library load failure: libdaplscm.so.2: cannot open shared object file: No such file or directory

As UDAPL is removed in newer OpenMPI versions anyway, this is fixed by running

echo "btl = ^udapl" >> /opt/openmpi/etc/openmpi-mca-params.conf

on all compute nodes and the head node.

So all in all, you can simply add the following lines to /export/rocks/install/site-profiles/6.1.1/nodes/extend-compute.xml and rebuild your compute node image:

echo "btl = ^udapl" >> /opt/openmpi/etc/openmpi-mca-params.conf
sed -i 's/add rocks-openmpi/add rocks-openmpi_ib/g' /etc/profile.d/rocks-hpc.*sh
echo "options mlx4_core log_num_mtt=24" >> /etc/modprobe.d/mlx4.conf
dracut -f 2.6.32-504.16.2.el6.x86_64 # may need to rebuild the initrd so it picks up the modprobe parameters

Leserbrief “Vorratsdatenspeicherung”

Am 15. April 2015 kündigte Justizminister H. Maas an, die Vorratsdatenspeicherung wieder einführen zu wollen, die er selber jahrelang kritisiert hatte und die im Jahr 2010 vom Bundesverfassungsgericht und im Jahr 2014 vom Europäischen Gerichtshof verboten worden war. Am 27. April 2015 druckte die Süddeutsche Zeitung dazu einen von mir verfassten Leserbrief:

Elektronische Fußfessel für alle

Wie kann die Antwort auf die überbordende und ungesetzliche Überwachung durch westliche Geheimdienste wie NSA, BND und GCHQ sein, noch größere Datenmassen anzusammeln? In einem Rechtsstaat dürfen erst bei konkretem Verdacht Überwachungsmaßnahmen ergriffen werden, sonst besteht die Gefahr, dass die Bürger den Gebrauch ihrer Freiheiten einschränken, um bloß nicht als falsch-positiver Treffer bei einer Rasterfahndung aufzufallen.

Die Befürworter der Vorratsdatenspeicherung argumentieren unlauter: Es werden Einzelfälle verallgemeinert, um eine Notwendigkeit der Wiedereinführung zu belegen. Es werden seriöse Gutachten ignoriert, die der Vorratsdatenspeicherung keinen nennenswerten Nutzen für die Strafverfolgung attestieren. Es werden gar frei erfundene Beispiele genutzt, siehe Sigmar Gabriels Behauptung, die Vorratsdatenspeicherung habe bei der Aufklärung der Anschläge von Norwegen 2011 geholfen. Wenn die Vorratsdatenspeicherung aber gar nicht die Verfolgung schwerer Straftaten erleichtert, warum verlangt die Politik sie denn dann?

Wenn schon die Kommunikationsdaten nicht von Nutzen sind, liegt die Vermutung nahe, dass der Staat es auf die Mobilfunk-Standortdaten abgesehen hat: Fortwährende Speicherung der Aufenthaltsorte aller Mobiltelefone in Deutschland, quasi elektronische Fußfesseln für die gesamte Bevölkerung, ohne dass diese sie bemerkt – ein Traum für jeden Sicherheitspolitiker, ein Albtraum für die Väter und Mütter des Grundgesetzes.

Die nächsten beiden Jahre großer Koalition werden sehr schwer für die SPD: Sie hat alle ihre Wünsche aus dem Koalitionsvertrag bereits erfüllt bekommen, jetzt besteht die Union auf die Umsetzung ihrer eigenen Projekte. Vielleicht ist es an der Zeit für die SPD, die Koalition einfach aufzukündigen.

Michael Kuron, Frickenhausen