Christopher | m d3velopment

July 8, 2013July 8, 2013

Caching Name Server for CentOS 6.x

A caching only DNS server caches DNS query results for the domain name being queried. These chache are stored for pre specified time known as the TTL ( time-to-live). A caching only name server will find the answer to name queries and remember the answer the next time you need it. This will shorten the waiting time the next time significantly, especially if you’re on a slow connection.

Step 1: Install the BIND Packages using Yum

Install bind packages using below command. In CentOS the caching-nameserver package has been included with bind package.

# yum install bind bind-chroot

Step 2: Copy default bind configuration File

Copy bind configuration file from bind sample files using below command. Change the path of files as per version you have installed.

cd /var/named/chroot/etc
cp /usr/share/doc/bind-9.9.2/sample/etc/named.conf  .
cp /usr/share/doc/bind-9.9.2/sample/etc/named.rfc1912.zones  .

Step 3: Make changes in Configuration File

Edit bind configuration file in your favorite editor and make necessory changes as per below settings or use below configuration.

// /var/named/chroot/etc/named.conf
options {
        listen-on port 53 { 127.0.0.1; any; };
        listen-on-v6 port 53 { ::1; };
         Continue reading "Caching Name Server for CentOS 6.x"

June 25, 2013June 25, 2013

Install Dell OpenManage on CentOS 6.4x

I have updated my Dell OpenManage installer script to address several compatibility issues with Dell PowerEdge G12+ systems. The following Dell OpenManage Server Administrator (OMSA) installation script is suitable for RedHat 6.4x and CentOS 6.4x systems

1. Login to your server via SSH.
2. Change directories to your source store:

# cd /usr/src

3. Create the install script:

# nano -w dominstaller.sh

4. Cut and paste the following text:

#!/bin/bash # # Dell OpenManage Installer (DOMI) # Revision: June 25th 2013 md3v.com # HOST=`hostname` D=`date '+%d%m%y'` echo echo "Dell OpenIPMI & OpenManage Automatic Installer" echo "Revision: July 25nd 2013 md3v.com" echo read -p "Press [Enter] key to begin the installation or [CTRL+C] to exit." echo echo "Installing OpenIPMI..." echo yum -y install OpenIPMI echo Continue reading "Install Dell OpenManage on CentOS 6.4x"

June 23, 2013June 23, 2013

Remotely wipe a Linux based server

There may come a time when you need to remotely wipe a Linux based server. Maybe your server has been compromised, is no longer required in production or, for security reasons, you simply need to make sure that the server is fully erased and no longer recoverable.

Note: This process is specifically designed for headless servers, e.g. server which do not have a locally (or remotely – think KVM) screen, keyboard or mouse. There are other options available for locally accessible servers which a DBAN (or similar solution) can be ran on.

Step 1: SSH into the server then type:

# dd if=/dev/zero of=/dev/sdaX

To check the correct hard disk device to wipe use:

#df -h

The DD command will copy zeros over the whole disk, rendering any existing data useless.

Step 2: Wait approximately ~10 minutes (more for good (or worse?) measure) after which time run:

# echo 1 > /proc/sys/kernel/sysrq
# echo o > /proc/sysrq-trigger

These commands will initiate a full power off of the server.

For click here for more information on the sysrp command and here for information on the sysrp-trigger command.

May 12, 2013

CompTIA CASP Training

I recently completed CompTIA Advanced Security Practitioner (CASP) training. The CASP certification is an international, vendor-neutral exam that proves competency in enterprise security; risk management; research and analysis; and integration of computing, communications, and business disciplines. The CASP is essentially a technical version of the ISC(2) CISSP (Certified Information Systems Security Professional) and is a DoD 8570 directive (IA Technical Level III) approved certification. I have held a CISSP certification since November 2001 and have recently been refreshing and upgrading a number of my certifications.

The CISSP has more policy and managerial topics covered under its objectives whereas CASP is more hands-on, technical and task oriented. One way to look at it is that CISSP explains ‘Why?’ and CASP lets you know ‘How?’

I will be spending time studying for the next 2-3 weeks before taking the exam. The CASP exam is notoriously difficult with only a 20% first-time pass rate. The exam is full of performance based questions which utilize simulators in a lab configuration. The CASP exam is also expensive at nearly $400.00 USD to take vs. the CISSP which cost $600.00 USD.

I’ll update this post once I’ve taken the exam and share my experience. Wish me luck!

May 12, 2013

Dell OpenManage Command Line

Dell’s OpenManage product consists of a number of network management and systems management applications which are made available via a secure, web-based dashboard. The dashboard is usually located a http://host.domain.net:1311.

A number of technical senarios such as restrictive firewall configurations or server level scripts may raise the need for Dell Open Manage (DOM) commands to be initiated from the command line. This short articles serves to outline some of the commands available and their use.

There are five main command line modules available for Dell OpenManage:

Command	Used For	Component Of
omreport	Read hardware settings and state information	OpenManage Server Administrator
omconfig	Set hardware options like BIOS settings	OpenManage Server Administrator
racadm	Read or set configuration of the Dell Remote Access Card	OpenManage Deployment Toolkit
syscfg	Read or set BIOS options	OpenManage Deployment Toolkit
raidcfg	Read or set options for the RAID controller	OpenManage Deployment Toolkit

Each of these commands can be initialized from the bash shell (Linux) or command line (Windows) in the same way any other system application can be ran.

An example is outlined below:

[root@server ~]# omreport chassis temps Temperature Probes Information

————————————
Main System Chassis Temperatures: Ok
————————————

Index                     : 0
Status                    : Ok
Probe Name                : PROC Temp
Reading                   : 48.0 C
Minimum Warning Threshold : 10.0 C
Maximum Warning Threshold : 120.0 C
Minimum Failure Threshold : 5.0 C
Maximum Failure Threshold : 125.0 C
</snip>

Other command line examples are available at: http://linux.dell.com/wiki/index.php/OpenManage_command_line_interface and instructions on install Dell OpenManage for Linux are available in my blog here.