inadyn is a C based client used to update DNS entries. Inadyn is an IP update client for, , etc.

Why we need this? Well you don’t really need this if you are using static IP.

But if you have dynamic IP, you must keep your IP updated with the domain you choose in or  every time you restart the router. Otherwise, the visitors can’t reach to your server.


apt-get update && apt-get install inadyn

or you can download inadyn:

cd /usr/src



cp inadyn/bin/linux/inadyn /usr/bin/inadyn

Change the file permission:

chmod 755 /usr/bin/inadyn

Configuration file for inadyn:

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Varnish is a web accelerator. Its mission is to sit in front of a web server an cache the content. It makes your web site go fast.
In this mode, Varnish will stop incomplete HTTP requests from reaching your Apache webserver.

Installing Varnish:

Varnish is distributed in the Debian package repositories, but the version there might be out of date, and  generally recommend using the packages provided by or packages from

To use the repository and install varnish, do the following:

Change Varnish settings:

1. First change the default port.  Edit /etc/default/varnish:

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dd is a common Unix program whose primary purpose is the low-level copying and conversion of raw data.

dd is used to copy a specified number of bytes or blocks, performing on-the-fly byte order conversions, as well as more esoteric EBCDIC to ASCII conversions. dd can also be used to copy regions of raw device files, e.g. backing up the boot sector of a hard disk, or to read fixed amounts of data from special files like /dev/zero or /dev/random.

In this article i will provide you some practical examples on using dd command to backup the Linux system. dd is a powerful UNIX utility, which is used by the Linux kernel makefiles to make boot images. It can also be used to copy data.

1. Backup Entire Harddisk

dd if=/dev/sda of=/dev/sdb

  • “if” represents inputfile, and “of” represents output file. So the exact copy of /dev/sda will be available in /dev/sdb.
  • If there are any errors, the above command will fail. If you give the parameter “conv=noerror” then it will continue to copy if there are read errors.
  • Input file and output file should be mentioned very carefully, if you mention source device in the target and vice versa, you might loss all your data.

In the copy of hard drive to hard drive using dd command given below, sync option allows you to copy everything using synchronized I/O.

# dd if=/dev/sda of=/dev/sdb conv=noerror,sync

2. Create an Image of a Hard Disk

 dd if=/dev/hda of=~/hdadisk.img

3. Restore using Hard Disk Image

To restore a hard disk with the image file of an another hard disk, use the following dd command example.

 dd if=hdadisk.img of=/dev/hdb

The image file hdadisk.img file, is the image of a /dev/hda, so the above command will restore the image of /dev/hda to /dev/hdb.

4. Backup a Partition

dd if=/dev/hda1 of=~/partition1.img

5. CDROM Backup

dd command allows you to create an iso file from a source file. So we can insert the CD and enter dd command to create an iso file of a CD content.

 dd if=/dev/cdrom of=tgsservice.iso bs=2048

What is ebtables? (Ethernet bridge frame table administration)

The ebtables utility enables basic Ethernet frame filtering on a Linux bridge, logging, MAC NAT and brouting. It only provides basic IP filtering, the full-fledged IP filtering on a Linux bridge is done with iptables. The so-called bridge-nf code makes iptables see the bridged IP packets and enables transparent IP NAT. The firewalling tools iptables and ebtables can be used together and are complementary. ebtables tries to provide the bridge firewalling that iptables cannot provide, namely the filtering of non-IP traffic.

What can ebtables do?

  • Ethernet protocol filtering.
  • MAC address filtering.
  • Simple IP header filtering.
  • ARP header filtering.
  • 802.1Q VLAN filtering.
  • In/Out interface filtering (logical and physical device).
  • MAC address nat.
  • Logging.
  • Frame counters.
  • Ability to add, delete and insert rules; flush chains; zero counters.
  • Brouter facility.
  • Ability to atomically load a complete table, containing the rules you made, into the kernel. See the man page and the examples section.
  • Support for user defined chains.
  • Support for marking frames and matching marked frames.

Install ebtables:

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Installing WebVZ

Step 1. First we need some prerequisites:

apt-get install  irb1.8 libopenssl-ruby1.8 libreadline-ruby1.8 rdoc1.8 ruby rubygems libsqlite3-ruby sqlite3

Step 2. Next we will download and install WebVZ in the directory /usr/local/webvz:

cd /usr/local
tar xvfz webvz.2.0.tar.gz
mv webvz.2.0 webvz
cd webvz

Step 3. We need to create some symlinks for webvz to work

ln -s /var/lib/vz /vz
ln -s /usr/bin/irb1.8 /usr/bin/irb
mkdir /etc/sysconfig
ln -s /etc/vz/conf /etc/sysconfig/vz-scripts

Step 4. Now we can install WebVZ as follows:

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