May 15, 2010
Adding modsecurity rule for domain
Linux General,Add the below rule in the .htaccess file. SecRuleEngine Off This will work only if you have old version of mod_security installed on the server. You cannot disable mod_security2 using .htaccess, the only way to bypass mod_security2 in Apache 2 is to manually edit httpd.conf. Create a directory with the username and the domain name,…
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May 11, 2010
Mysql Queries in Linux
Linux General,How to resolve mysql_connect() Error Warning: mysql_connect() [function.mysql-connect]: Access denied for user ‘username’@’localhost’ (using password: YES) Possible root cause for this problem is proper privilege not assigned to the particular user. So providing proper privileges will solve this issue. $grant all privileges on “Database_Name” to “username@localhost” identified by “password” If the mysql resides in the…
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May 8, 2010
SolusVM Master Installation
Blade / Virtualization,Linux General,SolusVM Solus Virtual Manager (SolusVM) is a powerful GUI based VPS management system with full OpenVZ, Xen Paravirtualization and Xen HVM support. SolusVM allows you and your clients to manage a VPS cluster with security & ease. Requirements SolusVM requires the following specification:CentOS 5+ based linux operating systemAt least one external IP addressOpenVZ – Ensure…
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May 8, 2010
Does DNS use TCP or UDP or both?
Linux General,Does DNS use TCP or UDP or both? TCP is a connection-oriented protocol and it requires data to be consistent at the destination and UDP is connection-less protocol and doesn’t require data to be consistent or don’t need a connection to be established with host for consistency of data. UDP packets are smaller in size.…
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May 7, 2010
Linux – Advanced Commands
Linux General,Show status of ethernet interface eth0: ethtool eth0 List addresses for interfaces: ip addr show (OR) ip a Set default gateway: ip route add default via 1.2.3.254 List routing table: ip route show Add (or del) ip and mask (255.255.255.0): ip addr add 1.2.3.4/24 brd + dev eth0 Text Manipulation: Replace string1 with string2: sed…
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May 7, 2010
Linux – Ethernet bonding
Linux General,Linux bond or team multiple network interfaces (NIC) into single interface We have two Dell servers that need setup with Intel Dual Gig NIC. My idea is to improve performance by pumping out more data from both NIC without using any other method. This box act as heavy duty ftp server. Each night I need…
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May 7, 2010
Linux – Tweaks
Linux General,Fork Bomb on Linux/Unix: Q. Explain following bash code or bash fork() bomb? : () { : | :& };: A. This is a bash function. It gets called recursively (recursive function). This is most horrible code for any Unix / Linux box. It is often used by sys admin to test user processes limitations…
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March 24, 2010
How to identify CPU resource problem?
FreeBSD,Linux General,vmstat command helps us to determine if a server is running short of CPU resources. First, let us determine the number of CPUs available Linux: $ grep -i processor /proc/cpuinfo | wc -l FreeBSD: $ sysctl -a ‘hw.ncpu’ Run vmstat command 10 times with an interval of 5 seconds $ vmstat 5 10 procs ———–memory———-…
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March 16, 2010
Extract the contents of an RPM
Linux General,Using rpm2cpio command, the contents of an RPM package can be extracted without having to install the package. For source RPMs too this command can be used. This is illustrated with an example as follows, where we extract the contents of RPM, google-chrome-beta_current_i386.rpm. $ rpm2cpio google-chrome-beta_current_i386.rpm | cpio -idv ./etc/cron.daily ./etc/cron.daily/google-chrome ./opt/google/chrome ./opt/google/chrome/chrome ./opt/google/chrome/chrome-sandbox ./opt/google/chrome/chrome.pak…
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March 16, 2010
Nagios Installation and Configuration
Linux General,Monitoring,Nagios Installation in Ubuntu Required Packages Install the following packages on Ubuntu before continuing. Apache 2 PHP GCC compiler and development libraries GD development libraries If not installed, using apt-get the above packages can be installed as follows sudo apt-get install apache2 sudo apt-get install libapache2-mod-php5 sudo apt-get install build-essential sudo apt-get install libgd2-xpm-dev Create…
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