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
Does DNS use TCP or UDP or both?
Linux General,Does DNS Use TCP or UDP? Understanding When DNS Uses Each Protocol The Domain Name System (DNS) is one of the most important services on the internet. Every time you visit a website, send an email, or connect to an online service, DNS translates the domain name (such as example.com) into an IP address that…
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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 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 13, 2010
Difference between Buffer and Cache
Linux General,Buffers are allocated by various processes to use as input queues, etc. Most of the time, buffers are some processes’ output, and they are file buffers. A simplistic explanation of buffers is that they allow processes to temporarily store input in memory until the process can deal with it. Difference between Buffer and Cache Cache…
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March 13, 2010
Memory Usage in Linux
Linux General,Check the memory usage on a linux system with the command given below. The free command helps in getting the memory usage in the system [rams@stopprepare-lx ~]$ free -m total...
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March 13, 2010
Disable the Error Beep in MySQL
Linux General,To temporarily disable the beep, pass –no-beep along when logging into the server: %>mysql -u root -p –no-beep To permanently disable this annoyance, add no-beep to the [client] section of your .my.cnf file.
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