Linux on Life

Fixing GlusterFS Geo-Replication Failure on Fedora

Fri, 21 Sep 2018 08:16:00 +0530

GlusterFS geo-replication can fail on Fedora due to a missing dynamic library symlink.

Checking /var/log/glusterfs/geo-replication/gv0_node1/gsyncd.log reveals:

class Changes(object):
 File "/usr/libexec/glusterfs/python/syncdaemon/libgfchangelog.py", line 19, in Changes
 use_errno=True)
 File "/usr/lib64/python2.7/ctypes/__init__.py", line 361, in __init__
 self._handle = _dlopen(self._name, mode)
OSError: /usr/lib64/libgfchangelog.so: cannot open shared object file: No such file or directory

Looking at /usr/libexec/glusterfs/python/syncdaemon/libgfchangelog.py:

class Changes(object):
 libgfc = CDLL("/usr/lib64/libgfchangelog.so", mode=RTLD_GLOBAL,
 use_errno=True)

On Fedora and RHEL, bare .so library symlinks (as opposed to versioned sonames like .so.0) are provided by the -devel development packages. To resolve this error, install the development package:

Building the Canon MF3010 Printer Driver on Fedora 25

Wed, 16 Nov 2016 14:49:00 +0530

To build the Canon imageCLASS MF3010 Linux driver from source, download the “UFR II/UFR II LT Printer Driver for Linux V3.20” archive from Canon’s support website.

On Fedora 25, you need two adjustments to build the RPM cleanly:

1. Spec File Patch (`cndrvcups-common.spec`)

Exclude internal dependency requirements and apply the gmodule patch:

--- cndrvcups-common.spec.orig 2016-11-16 14:37:13.341877857 +0530
+++ cndrvcups-common.spec 2016-11-16 14:34:40.674461102 +0530
@@ -1,5 +1,6 @@
 %define VERSION 3.60
 %define RELEASE 1
+%global __requires_exclude ^libcaiousb.so$

 %ifarch x86_64
 %define libs32 /usr/lib
@@ -19,6 +20,7 @@ Vendor: CANON INC.
 Group: Applications/Publishing

 Source: cndrvcups-common-%{version}-%{release}.tar.gz
+Patch0: cndrvcups-common-gmodule.patch

 BuildRoot: %{_tmppath}/%{name}-root

@@ -27,6 +29,8 @@ BuildRoot: %{_tmppath}/%{name}-root
 %prep
 %setup -q

+%patch0 -p1
+
 cd buftool
 ./autogen.sh --prefix=%{_prefix} --enable-progpath=%{_bindir} --libdir=%{_libdir} --disable-shared --enable-static

2. Add `gmodule` Dependency Patch

In modern Fedora releases, gmodule must be explicitly included in PKG_CHECK_MODULES:

Running Sky (tel.red) on Fedora 25

Thu, 01 Sep 2016 13:41:00 +0530

On Fedora 25, the Sky Skype for Business client crashes on launch inside its bundled Qt 5 runtime:

Program received signal SIGABRT, Aborted.
0x00007ffff112692f in raise () from /lib64/libc.so.6
(gdb) bt
#0 0x00007ffff112692f in raise () at /lib64/libc.so.6
#1 0x00007ffff112852a in abort () at /lib64/libc.so.6
#2 0x00007ffff200dcb1 in () at /usr/lib/sky/lib/libQt5Core.so.5
#3 0x00007ffff24ee835 in QGuiApplicationPrivate::createPlatformIntegration() () at /usr/lib/sky/lib/libQt5Gui.so.5
#4 0x00007ffff24ee955 in QGuiApplicationPrivate::createEventDispatcher() () at /usr/lib/sky/lib/libQt5Gui.so.5
#5 0x00007ffff21cea64 in QCoreApplicationPrivate::init() () at /usr/lib/sky/lib/libQt5Core.so.5
#6 0x00007ffff24f2340 in QGuiApplicationPrivate::init() () at /usr/lib/sky/lib/libQt5Gui.so.5
#7 0x00007ffff2be62b9 in QApplicationPrivate::init() () at /usr/lib/sky/lib/libQt5Widgets.so.5
#8 0x0000000000434e41 in main ()

The issue stems from incompatible bundled Qt libraries. A reliable workaround is to force Sky to use Fedora’s system-provided qt5 packages:

Installing Splunk Universal Forwarder Using Ansible

Sun, 07 Aug 2016 21:58:00 +0530

Here is an automated approach to installing and initializing the Splunk Universal Forwarder with Ansible.

Variables

splunk_home: /opt/splunkforwarder
splunk_exec: "{{ splunk_home }}/bin/splunk"

Playbook Tasks

- name: Install Splunk Universal Forwarder package
 yum:
 name: splunkforwarder
 state: latest
 become: yes

- name: Check for first-time-run marker file
 stat:
 path: "{{ splunk_home }}/ftr"
 register: result_splunk_ftr_stat

- name: Configure Splunk forwarder on initial installation
 block:
 - name: Ensure existing running splunkd process is stopped
 shell: ps aux | grep -v grep | grep splunkd && pkill -9 splunkd || true

 - name: Accept license agreement and start service
 shell: "{{ splunk_exec }} start --accept-license --answer-yes --no-prompt"

 - name: Enable Splunk forwarder boot-start service
 shell: "{{ splunk_exec }} enable boot-start"
 when: result_splunk_ftr_stat.stat.exists
 become: yes

Run the playbook, and your forwarder is initialized and configured to start on boot.

phpIPAM Behind a Load Balancer with SSL Offloading

Sat, 07 May 2016 10:06:00 +0530

phpIPAM supports SSL offloading via standard X-Forwarded-Proto and X-Forwarded-For HTTP request headers:

public function createURL () {
 // Reset URL for base
 if ($_SERVER['SERVER_PORT'] == "443") {
 $url = "https://$_SERVER[HTTP_HOST]";
 }
 // Reverse proxy doing SSL offloading
 elseif (isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && $_SERVER['HTTP_X_FORWARDED_PROTO'] == 'https') {
 $url = "https://$_SERVER[SERVER_NAME]";
 }
 elseif (isset($_SERVER['HTTP_X_SECURE_REQUEST']) && $_SERVER['HTTP_X_SECURE_REQUEST'] == 'true') {
 $url = "https://$_SERVER[SERVER_NAME]";
 }
 // Custom port
 elseif ($_SERVER['SERVER_PORT'] != "80") {
 $url = "http://$_SERVER[SERVER_NAME]:$_SERVER[SERVER_PORT]";
 }
 // Normal HTTP ...

However, if your load balancer does not forward this header or SSL offloading is misconfigured, phpIPAM may generate broken HTTP redirect loops or fail to load CSS and JavaScript assets.

Disabling SSL Verification in pyVmomi with Python

Thu, 31 Mar 2016 23:39:00 +0530

Working with self-signed vCenter certificates in an enterprise environment (such as RHEL 6 running mixed Python 2.6/2.7 and pyvmomi 5.5+) often leads to this error:

File "/usr/lib/python2.6/site-packages/requests/adapters.py", line 447, in send
 raise SSLError(e, request=request)
requests.exceptions.SSLError: [Errno 1] _ssl.c:492: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed

If you need a quick workaround to bypass certificate verification in development scripts:

import ssl
import requests
from pyVim.connect import SmartConnect

context = None
try:
 # Disable SSL certificate verification via standard library
 context = ssl.SSLContext(ssl.PROTOCOL_SSLv3)
 context.verify_mode = ssl.CERT_NONE
except AttributeError:
 # Fallback monkey-patch for older Python/requests environments
 rget = requests.get
 requests.get = lambda obj, *args, **kwargs: rget(obj, verify=False)
 requests.packages.urllib3.disable_warnings()

# Connect to ESXi / vCenter
si = SmartConnect(
 host=args.host,
 user=user,
 pwd=args.password,
 port=int(args.port),
 sslContext=context
)

This bypasses certificate validation issues so you can get back to writing your automation scripts.

Fixing BSNL DNS Redirection to domain-error.com

Mon, 28 Mar 2016 17:18:00 +0530

BSNL’s default DNS servers hijack unresolved domain queries and redirect users to ad-laden spam pages like http://domain-error.com.

To prevent this ISP hijacking, configure NetworkManager to ignore ISP-assigned DNS servers and use Google Public DNS instead.

Edit your NetworkManager connection profile in /etc/NetworkManager/system-connections/:

[ipv4]
dns=8.8.8.8;8.8.4.4;
dns-search=
method=auto
ignore-auto-dns=true

Alternatively, you can configure this graphically or via the terminal interface with nmtui:

sudo nmtui

References

Using Zabbix 3.0 on Enterprise Linux 6 (EL6)

Wed, 23 Mar 2016 17:47:00 +0530

Zabbix 3.0 requires PHP 5.4 or above and is consequently not officially available in base RHEL/CentOS 6 repositories.

To run Zabbix 3.0 with MariaDB 10.1 and PHP 5.6 (php56u), I built packages for EL6 on Fedora COPR: COPR: ritz/zabbix30

These RPMs are built for Zabbix 3.0.1 linked against MariaDB 10.1.x and PHP 5.6.19.

Useful Resources

Using C++ REST SDK (Casablanca) on Fedora Linux

Sun, 13 Mar 2016 17:23:00 +0530

Microsoft has open-sourced Casablanca (the C++ REST SDK) on GitHub.

To make it easy to use on Fedora, I packaged and published RPMs on Fedora COPR: COPR: ritz/cpprestsdk

To enable the repository and install:

sudo dnf copr enable ritz/cpprestsdk
sudo dnf install cpprest-devel

Happy compiling with -lcpprest!

Lync on Linux

Mon, 13 Jul 2015 20:58:00 +0530

If you are looking to run Microsoft Lync (aka Skype for Business) on Linux, you’re in luck: Fisil maintains a Linux client hosted at tel.red.

However, I ran into an issue running the client on Fedora 23 (Rawhide), as the Sky package bundles its own older X11 libraries:

$ sky
/opt/sky_linux/sky: symbol lookup error: /lib64/libXxf86vm.so.1: undefined symbol: _XEatDataWords

_XEatDataWords was added to fix an upstream X.Org vulnerability (commit details). The workaround is to preload your distribution’s native libX11 library:

Closing Apps in Window Picker Mode in GNOME Shell

Sun, 25 Dec 2011 21:20:00 +0530

One of the pain points when using a touchscreen device is closing applications while in window picker (overview) mode.

Why not add a “Trash Can” target to the dash or dock where windows can simply be dragged and dropped to close them? It would only need to be visible while in the window picker overview.

Thoughts?

Tablets: Unity and GNOME Shell

Sat, 24 Dec 2011 08:17:00 +0530

I have been thinking about writing this down for quite a while: my hands-on experiences testing Ubuntu Unity and GNOME Shell on the WeTab tablet.

Unity

Unity makes a fine netbook interface, but tablet support feels underdeveloped. After configuring auto-login, I was greeted by the standard desktop and launcher. However, launching an application and maximizing it hides the dock launcher entirely, making it awkward to bring back with a finger. Furthermore, scrollbars are difficult to grab, and multi-touch gestures like drag-to-scroll aren’t yet implemented. Aside from those tablet friction points, the interface shows potential.

FUDCon 2011: Here I Come!

Tue, 01 Nov 2011 00:04:00 +0530

I am heading to FUDCon Pune this year! I hope to present a talk to help newcomers get started with contributing to open source, specifically within the GNOME project.

Please check out and vote for my session here: Contributing to Open Source (FUDCon Session)

Changing Brightness from GNOME Shell

Wed, 07 Sep 2011 23:23:00 +0530

gnome-power-manager was rewritten for GNOME 3.2 and merged directly into gnome-settings-daemon (g-s-d) as a plugin responsible for system power policy. Most power management is handled by UPower, with backlight brightness being a key exception. Backlight is managed at the session level by gnome-settings-daemon via its power plugin using XRandR or standard sysfs, depending on hardware and driver support.

To read screen brightness over D-Bus:

gdbus call --session \
 --dest org.gnome.SettingsDaemon \
 --object-path /org/gnome/SettingsDaemon/Power \
 --method org.gnome.SettingsDaemon.Power.Screen.GetPercentage

Why bother with this? On a tablet device (such as the WeTab), brightness settings were buried deep in system menus and cumbersome to reach. With the custom GNOME Shell brightness extension (download archive), you can adjust screen brightness directly from the top bar. This requires patching gnome-settings-daemon to emit the Changed signal (GNOME Bug 658493).

Linux and the Desktop

Sun, 07 Aug 2011 00:38:00 +0530

It’s been a blast—Linux on the desktop never ceases to amaze me.

The Year 2038 Problem (Y2038)

Tue, 14 Jun 2011 16:22:00 +0530

Why should you migrate to x86_64 over 32-bit?

The Year 2038 Problem is not something you want to run into. Do your part: ensure your applications build and run cleanly on 64-bit systems, and move to x86_64.

(Looking at you, Flash and Skype: ಠ_ಠ)

Running 32-bit Flash on 64-bit Fedora with 64-bit Chrome

Tue, 14 Jun 2011 13:53:00 +0530

To set up 32-bit Flash in 64-bit Chrome on Fedora x86_64:

Download and install the adobe-release RPM package from Adobe Flash Player.
Install the Flash plugin and 32-bit compatibility wrapper packages:

sudo yum install flash-plugin
sudo yum install alsa-plugins-pulseaudio.i686 nspluginwrapper.i686 nspluginwrapper.x86_64

Link the wrapped plugin into your 64-bit Mozilla plugins directory:

cd /usr/lib64/mozilla/plugins
sudo ln -s ../plugins-wrapped/nswrapper_32_64.libflashplayer.so .

Restart Chrome, and you are done!

Dell ST2220T Touchscreen Monitor on Linux

Tue, 14 Jun 2011 12:20:00 +0530

Good news: the Dell ST2220T multi-touch monitor works on Fedora Linux using evdev under Xorg!

Special thanks to Gopal for tracing and testing this. Additional hardware diagnostic info is posted in Red Hat Bugzilla 703118.

Pushing for xchat-gnome 0.26.3

Fri, 15 Apr 2011 16:49:00 +0530

xchat-gnome 0.26.2 has been tagged, though it hasn’t yet been uploaded to ftp.gnome.org. Instead, I am pushing for an immediate 0.26.3 release—hopefully the final release in the GTK+ 2.x series—followed by xchat-gnome 0.3.0 targeting GNOME 3.

GNOME Legacy and GNOME 3

Fri, 25 Feb 2011 22:02:00 +0530

For anyone who prefers to stick with “GNOME Legacy” (Fallback mode) rather than GNOME 3 with GNOME Shell, you can configure your default session by running:

cd /usr/share/gnome-session/sessions
sudo mv gnome.session gnome-new.session
sudo mv gnome-fallback.session gnome.session

Evolution Evolved

Tue, 23 Nov 2010 18:07:00 +0530

Notable improvements expected with the release of Evolution 3.0:

Migration of local mail storage from mbox to the faster, more resilient maildir format.
Built-in duplicate email detection and removal.
Significant memory usage and leak optimizations.

RHEL 6 Is Out

Mon, 15 Nov 2010 14:29:00 +0530

Red Hat Enterprise Linux 6 (RHEL 6) is out, and it brings a huge set of improvements over RHEL 5 for desktop users. Here is a curated list of highlights that I find particularly useful on an EL6 workstation:

Core System & Filesystems

Upstart: Replaces traditional SysV init (Upstart Wiki)
Dracut: Modern event-driven initramfs generator (Dracut Wiki)
ext4: Default robust filesystem (Fedora ext4 Feature)
Btrfs: Available as a technology preview (Btrfs in Fedora)

Boot & Graphics

Plymouth: Smooth graphical boot flicker-free animations (Plymouth)
Kernel Mode Setting (KMS): Native resolution and smooth transitions during boot (KMS)
Xorg 1.7:
- nouveau open-source driver for NVIDIA cards (Nouveau)
- R600 3D hardware acceleration for AMD/ATI Radeon (R600 Accel)
- xrandr 1.3 dynamic monitor handling (LWN Article)
- Native DisplayPort audio and video support

Performance & Security

Tickless Kernel: Significant power savings on idle systems (Tickless Kernel)
Tuned: Adaptive power management profiles (Power Management)
PolicyKit & XACE: Fine-grained privilege management without root elevation (Polkit)

Desktop & Multimedia

GDM PAM Stacks: Support for multiple authentication backends (Multiple PAM in GDM)
ConsoleKit Fast User Switching: Seamless desktop switching (Fast User Switching)
PulseAudio:
- Unified volume control across applications (Volume Control)
- Glitch-free audio playback via timer-based scheduling (Glitch-Free Audio)
IBus: Modern input method framework replacing SCIM (IBus)
Evolution 2.28: Native support for Microsoft Exchange 2007+ via OpenChange (OpenChange)
OpenOffice.org 3.x: Native support for reading and writing Office Open XML (.docx, .xlsx) documents
NetworkManager: System-wide connection profiles managed independently of user logins (System Connections)

Desktop Environments

GNOME 2.28 (major upgrade from 2.16 in RHEL 5)
KDE 4.3
Xfce available via EPEL
SPICE: High-performance remote desktop protocol support

Official Press Release: Red Hat Flexibility and Portability
Product Overview: Red Hat Enterprise Linux Desktop

HP TouchSmart tx2

Mon, 22 Feb 2010 18:48:00 +0530

I am the not-so-proud owner of an HP tx2 convertible tablet, and it has been quite a headache. It came preloaded with Windows Vista, along with an optional upgrade to Windows 7 available on request. The convertible laptop is heavy, has abysmal battery life, and heats up faster than a toaster.

On the positive side, the tx2 is relatively compact with its 12" display, easy to carry around, includes an optical drive (which I still use occasionally), and features mostly Linux-compatible hardware. The touchscreen works under Linux, although I’ve currently misconfigured something there.

BSNL Internet Connection and Security

Tue, 09 Jun 2009 11:25:00 +0530

In short: it’s terrible. Here is the longer story.

The Modem

The ISP-provided modem is a DNA A211. By default, it uses admin/admin credentials, and the web management console is accessible over Wi-Fi!

It appears to run a Linux 2.6.8 kernel, likely with a GNU-based userland stack. However, I haven’t been able to locate the GPL source code published anywhere on their website.

The modem requires a daily reboot to maintain a stable internet connection—I still haven’t figured that one out.

xchat-GNOME Fullscreen

Fri, 08 May 2009 19:56:00 +0530

You love chatting over IRC, IRC is life, and you need your IRC client to support fullscreen mode! Look no further: xchat-gnome requires only a trivial patch to support fullscreen.

For more information, see Fullscreen support for xchat-gnome (GNOME Bug 445638).

Yes, xchat-gnome needs your love!

Building RPMs Without Root

Fri, 08 May 2009 19:26:00 +0530

When building RPM packages, always avoid using the root account. Fedora 11 configures non-root building by default.

For instructions on patching and rebuilding source RPMs as a regular user, see: How to patch and recompile a source RPM

RPM, rpmbuild, and Macros

Fri, 08 May 2009 19:26:00 +0530

When building RPMs, avoid using the root account. Fedora 11 configures non-root packaging by default. On other systems, create a .rpmmacros file in your home directory with the following line:

%_topdir %{getenv:HOME}/rpmbuild

As an added bonus for systems with multilib architectures (such as x86_64), add this format string to .rpmmacros:

%_solve_name_fmt %{?_solve_pkgsdir}/%%{NAME}-%%{VERSION}-%%{RELEASE}.%%{ARCH}

Reference: How to patch and recompile a source RPM

Receiving Files from Phone to Computer

Wed, 25 Mar 2009 04:18:00 +0530

Duh! To receive files from a phone or other Bluetooth-enabled device to a laptop running Linux, make sure to enable the “Receive files in Downloads folder over Bluetooth” option in GNOME File Sharing Preferences.

Notes: Bluetooth on Fedora

SQLite vs. libgda

Sun, 22 Mar 2009 23:50:00 +0530

A few things I have learned:

DDL (Data Definition Language) varies significantly from one SQL implementation to another.
It is much easier and faster to maintain an application for a single database backend rather than across many.
libgda is great when you are designing an application specifically meant to manage arbitrary databases.
libgda is overkill when all you need is to maintain a simple, local embedded database.
SQLite is fast, lightweight, well-documented, and backed by an active IRC support community.
Keep database-related code restricted to as few source files as possible.
The SQLite source code is an excellent reference for understanding how to implement commands like .import.
Using Git (or any modern version control system) saves an enormous amount of time.

rt2860 on Fedora 11

Sun, 22 Mar 2009 23:41:00 +0530

For anyone missing the wireless driver on the Asus Eee PC 1000H: rt2860 has made it into kernel staging and is not yet part of Fedora 11. To build it yourself, download the latest snapshot from the Linux kernel git staging tree using the “snapshot” link.

Once downloaded, extract the archive and append the following line to the Makefile:

obj-m := rt2860sta.o

Then run the command below to compile and install the module:

Linux Hosts That Use the evdev Driver for Keyboards Do Not Map Keys Correctly in Any Guest in VMware

Fri, 21 Nov 2008 16:17:00 +0530

Some of the newer Linux distributions use Xorg 1.4, where the new evdev driver manages all input devices, including keyboards. The evdev driver causes the keyboard to send different keycodes. For example, the down arrow sends keycode 116, which other drivers interpret as Win+R. Consequently, keyboard mapping problems occur in all guest operating systems running in VMware.

Solution: VMware Knowledge Base Article 1007439

Closing a Hung SSH Session

Fri, 21 Nov 2008 15:51:00 +0530

How does one close an SSH session that has hung or disconnected from the server?

Use the key sequence ~. (tilde followed by a dot, typed at the beginning of a new line). For more information, check the SSH manual:

man ssh

Background

I was happily working on my system, accessing my test box remotely. Suddenly, there was darkness—or what most people call a power outage. Since my UPS was in the repair shop, my machine shut down and left me with a frozen SSH session upon rebooting and reconnecting.

Recovering a Partition Table

Fri, 21 Nov 2008 10:27:00 +0530

Oh no! You deleted, overwrote, or spilled coffee on your partition table! What’s next?

For almost anything (except the spilled coffee), you can check out TestDisk, available in Fedora. Simply launch it and follow the on-screen instructions.

Story

One fine day, with birds singing outside on a bright sunny afternoon, I decided to install Fedora on a test box. Incidentally, that machine had an old hard drive with lots of photos from my school and college days. And so, the saga began.

Key Mapping on RHEL 5

Mon, 14 Jul 2008 23:47:00 +0530

Multimedia keys [1] did not work on RHEL 5, which was missing the keymap quirk [2] patch written by rhughes. Backporting was fun while it lasted—now my life feels hollower than ever.

[1] https://bugzilla.redhat.com/show_bug.cgi?id=450326
[2] http://people.freedesktop.org/~hughsient/quirk/quirk-keymap-index.html