How to use tcpdump Command With Examples on Linux CentOS 5/CentOS 6/RHEL 5/RHEL 6

Tcpdump is a tool to dump the traffic on a network. It’s a packet sniffer that able to capture traffic that passes through a machine. It operates on a packet level, meaning that it captures the actual packets that fly in and out of your computer. If your linux server haven’t installed with tcpdump package, […]

How to Grep Multiples Lines and using Specific Keyword on Linux


grep is a command line text search utility originally written for Unix or linux. In linux you can grep multiple lines before or after matching the keywords. This examples has been tested on linux CentOS 6.2, but it may workings on other linux version such as Redhat Enterprise Linux 5 (RHEL5) or (RHEL6). Get grep […]

How to Install and Configure yum-priorities on RHEL 6/CentOS 6


In this post, i will show on how to install and configure yum-priorities on CentOS 6 or RHEL 6 Linux server. Theoretically, the repositories with the lowest numerical priority number have the highest priority. This is one of the method to prevents mistakes such as accidentally running yum upgrade with everything. This steps has been […]

How to Create and Extract a gzip Compressed Archive File on Linux


Archiving and compressing files are useful when creating backups and transferring data across a network. One of the oldest and most common commands for creating and working with the backup archives is tar command. tar originally stood for tape archiver. With tar, we cab gather large sets of the files into a single file(archive). We […]

How to use Basic Regular Expression with grep command on Linux


Regular expressions are special text strings that used to search for and match patterns in text. To make the search expression more specific, it can work together with the grep command. The grep command is the General Regular Expression Parser; it searches a file for strings matching a given regular expression, and by default it […]

How to Open the File in Read Only Mode on Linux


Question : How to open a file on read only mode on linux? Answer : This command has been tested on Redhat Enterprise linux 6 (RHEL6) server. To open the file with vim in read only mode on linux, you need to run “vim -R” as below. Vim is enhanced version of vi editor that […]

How Display Logged in User Information and Terminal number on Linux Server


In this post i will show on how to display logged in user information and terminal number on Linux server. This post provides practical examples for future references. This steps has been tested on Redhat Linux Enterprise server 6 and may working CentOS server as well. 1. “who am i” command is use to display […]

How to Fix “cannot restore segment prot after reloc: Permission denied” error While Restarting zmcontrol on Zimbra


Question : I want to start the Zimbra services. But i am getting the following issue while restarting zmcontrol using “zmcontrol start” command as per below error messages : [zimbra@mail ~]$ zmcontrol start Host mail.bloggerbaru.local Starting zmconfigd…Done. Starting logger…Done. Starting mailbox…Done. Starting antispam…Done. Starting antivirus…Done. Starting snmp…Done. Starting spell…Failed. Starting apache…httpd: Syntax error on line […]

How to Add Persistent Static Routes on RHEL 6/CentOS 6


This example will show you on how to configure the Persistent static route in RedHat Enterprise Linux 6 (RHEL 6) server. This configuration may different with other version of RHEL but the basic is almost the same. Persistent static route will permanently stored the setting and will not be deleted after rebooted. The following setting […]

How to Install nmap on RHEL 6 Linux Server


Nmap (“Network Mapper”) is a free and open source tool for network exploration or security auditing. It can help you to find open port on a network. Nmap very useful for system and network administrator to perform system and network administration’s task and sometimes may helps in troubleshooting to narrow down the issue. Nmap uses […]

How to Install and Configure Bind Chroot DNS Server on RHEL 6


In this post, i will guide you on how to install and configure Bind Chroot DNS server on Redhat Enterprise Linux 6 (RHEL 6). DNS is the Domain Name System that maintains a database that can help user’s computer to translate domain names to IP addresses. This post will show the installation and configuration for […]