# OpenVPN server fails to start on Debian Stretch

After a recent upgrade to Debian Stretch, my OpenVPN server stopped working. Checking the relevant log file, /var/log/openvpn.log, I found the following not very helpful error message.

Fri Nov 23 16:46:37 2018 OpenVPN 2.4.0 x86_64-pc-linux-gnu [SSL (OpenSSL)] [LZO] [LZ4] [EPOLL] [PKCS11] [MH/PKTINFO] [AEAD] built on Jul 18 2017
Fri Nov 23 16:46:37 2018 library versions: OpenSSL 1.0.2l  25 May 2017, LZO 2.08
Fri Nov 23 16:46:37 2018 daemon() failed or unsupported: Resource temporarily unavailable (errno=11)
Fri Nov 23 16:46:37 2018 Exiting due to fatal error


Fortunately, someone already reported this error to debian and found out that the error is caused by the

LimitNPROC=10


in the /lib/systemd/system/openvpn@.service. The LimintNPROC directive in systemd is used to limit the number of forks a service is allowed to make. Removing this limit, might not be the best idea. So, I would suggest that instead of commenting it out, to find out the minimal value that allows OpenVPN to start and work. After some testing, I found that the minimal value that worked for me is

LimitNPROC=27


After editing the /lib/systemd/system/openvpn@.service, you need to reload the systemd service files and restart the OpenVPN server process.

$sudo systemctl daemon-reload$ sudo systemctl restart openvpn@server


# Ubuntu Freezes When Booting with Degraded Raid

I tried testing my software raid (mdadm) setup by removing one of the disks. When I tried to boot the degraded system, the system hanged displaying a purple screen. If I try booting the system in recovery mode, I get the following error:

** WARNING: There appears to be one or more degraded RAID devices **
The system my have suffered a hardware fault, such as a disk drive failure. The root device may depend on the RAID devices being online.
Do you wish to start the degraded RAID? [y/N]:

# Installing Citrix Receiver on Ubuntu 64bit

It’s a hassle.

The first step is to grab the 64bit deb package from Citrix website. Next install it using dpkg:

~$sudo dpkg --install Downloads/icaclient_12.1.0_amd64.deb This results in the following error: dpkg: error processing icaclient (--install): subprocess installed post-installation script returned error exit status 2 Errors were encountered while processing: icaclient Which can be fixed by changing line 2648 in /var/lib/dpkg/info/icaclient.postinst:  echo$Arch|grep "i[0-9]86" &gt;/dev/null

to:

         echo $Arch|grep -E "i[0-9]86|x86_64" &gt;/dev/null And then execute ~$ sudo dpkg --configure icaclient

Credit for this part goes to Alan Burton-Woods.

Next, when trying to actually use the Citrix Receiver to launch any apps, I’ve encountered the following error:

Contact your help desk with the following information:
You have not chosen to trust "AddTrust External CA Root", the
issuer of the server's security certificate (SSL error 61)

In my case the missing root certificate was Comodo’s AddTrust External CA Root, depending on the certificate used by the server you’re trying to connect to, you may miss some other root certificate. Now you can either download the certificate from Comodo, or use the one in  /usr/share/ca-certificates/mozilla/AddTrust_External_Root.crt (they are the same). Either way, you should copy the certificate to the icaclient certificate directory:

\$ sudo mv /usr/share/ca-certificates/mozilla/AddTrust_External_Root.crt /opt/Citrix/ICAClient/keystore/cacerts/


These steps got Citrix working for me, but your mileage may vary.

# Annoying Outlook Error

Sadly, there are occasions where I can’t use my beloved Gmail account and have to use Outlook to connected to a corporate Exchange servers. Due to Exchange inability to efficiently operate with large mailboxes (at least that what the tech support there tells me), I have to resort to so move messages to a local PST. However, some time a go I’ve started encountering the following error whenever I’ve tried moving messages into a PST file:

Cannot move the items. The item cannot be move. It was either already moved or deleted, or access was denied.

I’ve tried changing permissions, moving my PST around, repairing it with some tools that comes bundled with Office (I read somewhere that such error can be caused by corrupted PST files), and even tried creating a new PST. But, alas, the not so helpful message just wouldn’t get a way.

# Python’s base64 Module Fails to Decode Unicode Strings

If you’ve got a base64 string as a unicode object and you try to use Python’s base64 module with altchars set, it fails with the following error:

TypeError: character mapping must return integer, None or unicode


This is pretty unhelpful error message also occurs if you try any method that indirectly use altchars. For example:

base64.urlsafe_b64decode(unicode('aass'))
base64.b64decode(unicode('aass'),'-_')


both fail while the following works:

base64.urlsafe_b64decode('aass')
base64.b64decode(unicode('aass'))


While it’s not complicated to fix it (just convert any unicode string to ascii string), it’s still annoying.

# NVidia driver fails to initialize after X restart

This is mainly a note to myself. Sometimes when the X server is restart it complains that nvidia driver couldn’t be initialized and that no screens were found. This may be a result of a version mismatch between X11’s and the kernel’s nvidia module. The solution is to

modprobe -r nvidia


before restarting the X server.

# \lyxframeend Undefined when Using Beamer with Lyx

I’m using LyX for the first time with Beamer. Making the title page was smooth. But when I’ve tried adding a new frame (using BeginFrame) I was confronted with the following error

 \lyxframeend
{}\lyxframe{Outline}
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., \hobx'), type I' and the correct
spelling (e.g., I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.

After comparing my document to example (working) beamer documents I’ve found out that you must have an EndFrame command after your last frame. Too bad it wasn’t documented anywhere I’ve found as this little thing drove me crazy.

# Kernel Configuration for acpid Issue

I’ve installed acpid on my system some time ago (Gentoo package: sys-power/acpid. However each time I tried to start it it complained:

acpid: can't open /proc/acpi/event: No such file or directory


Apparently acpid requires you to enable ACPI_PROC_EVENT, which in it’s labels states “Deprecated /proc/acpi/event support”. I really wonder why such tool only support the deprecated way to receive the ACPI events.

# LaTeX Error: Command \textquotedbl unavailable in encoding HE8

I was testing today the SVN version of LyX 1.6.0 and 1.5.7. Due to a change in the way the double quotation mark (“) is handled, adding it to Hebrew text resulted in the following LaTeX error:

LaTeX Error: Command \textquotedbl unavailable in encoding HE8

# Alpha Channel Problems When Creating .ico Files Using ImageMagick

I’ve tried to use ImageMagick to create .ico files for Open Yahtzee, out of PNGs of various sizes. The command as it should have been:

convert openyahtzee16.png openyahtzee32.png openyahtzee64.png openyahtzee.ico

resulted in the alpha channel being reversed. I’ve used ImageMagick 6.4.0, and I didn’t remember this misbehavior happening in the previous versions.

While this annoyed, and was due to no apparent reason, it could be easily solved using the ImageMagick switches to reverse the alpha channel:

-channel Alpha -negate

So the command that produces a correct .ico file was:

convert openyahtzee16.png openyahtzee32.png openyahtzee64.png -channel Alpha -negate openyahtzee.ico`