Wednesday, January 28, 2015

Ghost Glibc Library Vulerability (CVE-2015-0235)

For more information do take a look at GHOST: glibc vulnerability (CVE-2015-0235)

GHOST is a 'buffer overflow' bug affecting the gethostbyname() and gethostbyname2() function calls in the glibc library. This vulnerability allows a remote attacker that is able to make an application call to either of these functions to execute arbitrary code with the permissions of the user running the application.

The gethostbyname() function calls are used for DNS resolving, which is a very common event. To exploit this vulnerability, an attacker must trigger a buffer overflow by supplying an invalid hostname argument to an application that performs a DNS resolution.

Update the glibc and ncsd packages on your system

Restart vulnerable services that use glibc (since so many services use glibc, the safest option is to restart the system).

Thursday, January 15, 2015

SuseCon 2014 keynote speaker videos

There is a list of Keynote speaker videos taken from SuseCon 2014. Do take a look

SuseCon 2014 Videos

Wednesday, January 14, 2015

Cannot set user id: Resource temporarily unavailable while trying to login or su as a local user in CentOS

If you encounter this error while logging on or su --login as a user,

"cannot set user id: Resource temporarily unavailable" while trying to login or su as a local user.

In CentOS 6, the reason for this error is that the the user’s the number of executing threads has reached the nproc resource limit. You can solve the issues

You can edit /etc/security/limits.d/90-nproc.conf which is
# Default limit for number of user's processes to prevent
# accidental fork bombs.
# See rhbz #432903 for reasoning.

*          soft    nproc     1024
user1       soft    nproc    10240

More Information:
  1. Cannot set user id: Resource temporarily unavailable while trying to login or su as a local user in CentOS

Compiling and Configuring Python 3.4.1 on CentOS

Step 1: Remember to turn on RPMForge and EPEL Repository. For more information on repository, see Repository of CentOS 6 and Scientific Linux 6 

Step 2: Download Python-3.4.1 from the Python Download Page

Step 3: Install Prerequisite Software
# yum install openssl-devel bzip2-devel expat-devel gdbm-devel readline-devel sqlite-devel

Step 4: Configure and Build
# cd /installation_home/Python-3.4.1
# ./configure --prefix=/usr/local/python-3.4.1
# make
# make install

Step 5: Check that scripts query the correct interpreter:

Step 6: Install Scientific Components (Optional: If you requires it) Scipy Stack (for scientific packages in python)
# yum install numpy scipy python-matplotlib ipython python-pandas sympy python-nose

Step 7: Install Python Modules (whatever you need. Here is an example)
# /usr/local/python-3.4.1/bin/pip3 install networkx

Wednesday, January 7, 2015

Checking for Constant Time Stamp Counter

A Constant Time Stamp Counter is included in more recent Intel Processors (TSC) to reads at the processor's maximum rate regardless of the actual CPU running rate. While this makes time keeping more consistent, but it can skew benchmarks, where a certain amount of spin-up time is spent at a lower clock rate before the OS switches the processor to the higher rate. For more information on Time Stamp Counter, do look at Time Stamp Counter (wikipedia)

To check whether your CPU support TSC, you can issue the command
# grep -q constant_tsc /proc/cpuinfo && echo "Constant TSC detected" || echo "No Constant TSC Detected"

Monday, January 5, 2015

Kano - Make Machine Yourself.

Kano is powered by the Raspberry Pi Model B and  comes with color coded accessories packed in a nifty and good-looking box. The accessories includes
  1. Green Wi-Fi dongle; 
  2. Red Power Supply
  3. Yellow HDMI cable
  4. Orange Keyboard
  5. Transparent Kit Box
  6. Raspberry Pi Model B (ARM 700MHz CPU and 512MB RAM)
  7. DIY Speaker
  8. Manual with a story-like instruction.
  9. SD Card preloaded with Kano OS.
  10. Low Price of US$149.99