Monthly Archives: July 2013

Understanding SSH

ssh (SSH client) is a program for logging into a remote machine and for executing commands on a remote machine.  It is intended to replace rlogin and rsh, and provide secure encrypted communications between two untrusted hosts over an insecure … Continue reading

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Using TCP Wrappers to secure Linux

TCP Wrappers can be used to GRANT or DENY access to various services on your machine to the outside network or other machines on the same network. It does this by using simple Access List Rules which are included in … Continue reading

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TCPDUMP IN LINUX

tcpdump uses. tcpdump is a packet sniffer. It is 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. It … Continue reading

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Understanding /etc/fstab file in linux

What is fstab and why it’s useful fstab is a configuration file that contains information of all the partitions and storage devices in your computer./etc/fstab contains information of where your partitions and storage devices should be mounted and how. /etc/fstab … Continue reading

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WHO command with examples

[root@server~]# Who root     tty1         2012-03-01 09:05 (:0) root     pts/0        2012-03-01 09:47 (192.200.1.205) [root@server~]# who –a system boot  2012-03-01 09:03       run-level 5  2012-03-01 09:03 LOGIN      tty2         2012-03-01 09:03              2659 id=2 LOGIN      tty3         2012-03-01 09:03              2661 id=3 LOGIN      tty4         2012-03-01 09:03              2665 … Continue reading

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Apache Server Configuration in Linux

Install the required rpms #yum install httpd* Start The service # service httpd on Make sure service is automatically started at boot time # chkconfig httpd on Configure virtual hosting mkdir -p /var/www/virtual/www.alex.net/html cd /var/www/virtual/www.alex.net/html vim index.html            #do any coding … Continue reading

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Step by Step NIS Server Configuration

Server Side Configuration 1) export home directory on ur NIS server # vim /etc/exports 2) Activate the exported directory # exportfs  -a 3) start the following services # service nfs restart # service portmap restart # service nfslock restart 4) … Continue reading

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Telnet in Linux

Telnet is a program that allows users to log into your server and get a command prompt just as if they were logged into the VGA console.One of the disadvantages of Telnet is that the data is sent as clear … Continue reading

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TFTP in Linux

TFTP can be used with great versatility as a network management tool and not just for saving files. TFTP servers can be used to upload new configurations to replacement devices after serious hardware failures. They also can be used for … Continue reading

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XINETD in Linux

Many network enabled Linux applications don’t rely on themselves to provide restricted access or bind to a particular TCP port; instead they often offload a lot of this work to a program suite made just for this purpose, xinetd. Managing … Continue reading

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setup vnc server in linux

Step 1: Installing Vncviewer, Vncserver #yum install vnc Step 2: Configuring resolution, port & user The default location of server configuration file for vncserver is ‘/etc/sysconfig/’. To configure the resolution, user and port open ‘/etc/sysconfig/vncservers’ and add two lines per … Continue reading

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Configure Cacti in Linux

Cacti is a complete frontend to RRDTool, it stores all of the necessary information to create graphs and populate them with data in a MySQL database. The frontend is completely PHP driven. Along with being able to maintain Graphs, Data … Continue reading

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Setting UP DHCP SERVER In Linux

DHCP, or Dynamic Host Configuration Protocol, allows an administrator to configure network settings for all clients on a central server. The DHCP clients request an IP address and other network settings from the DHCP server on the network. The DHCP … Continue reading

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Install Munin (Network Monitoring) in RHEL, Centos and Fedora

Munin is an open source web based network monitoring application written in Perl that displays systems and networks output in graphs using RRDtool. With the help of Munin you can monitor the performance of your systems, networks, SANS’s and applications. … Continue reading

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Crontab Tutorial

A crontab file has six fields for specifying minute, hour, day of month, month, day of week and the command to be run at that interval. See below: *     *     *     *     *  command to be executed –     –     –     … Continue reading

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