Tag Archives: ip address

Centos Network Configuration – on a Barebones from Command Line

Centos LogoCentos Network Configuration – is very simple on a full installation. However, I downloaded the Centos’ “Minimal Install” cd and used yum to install various packages I needed.

The simple way to do it if you have a standard installation is to use the Network Administration
Tool (system-config-network), which is a graphical interface to edit the configuration files. Since I haven’t installed this tool, I needed to edit the files manually.

How to Configure Network in Centos from Command Line:

A quick way to see if your interface works and if you can ping internal resources.
ifconfig eth0 192.168.0.2 netmask 255.255.255.0
Use your IP addresses.
Note that this is not persistent, at the first reboot, ot first network services restart this will be lost.

For a DHCP address assignment use:
ifdown eth0
dhclient eth0

To get a persistent centos network configuration use the following procedure:

Edit the network configuration file

vi /etc/sysconfig/network-scripts/ifcfg-eth0
Edit the configuration file so it contains your IP address configuration as follows:
DEVICE="eth0"
BOOTPROTO=none
HWADDR="00:00:00:00:00:00"
NM_CONTROLLED="yes"
ONBOOT="yes"
GATEWAY=192.168.0.1
NETMASK=255.255.255.0
IPADDR=192.168.0.2
PEERDNS=no
USERCTL=no

This configures your interface with the IP 192.168.0.2 and the netmask 255.255.255.0.
For more info about Centos’ network configuration look here: .

Set up Name Resolution

Name resolution configuration, is more consistent across various Linux distributions. Most of the Linux distros will have the configuration file at /etc/resolv.conf.
Edit this file and change according to your network:
vi /etc/resolv.conf
Modify the file so it contains pointers to your DNS servers like this:
nameserver 192.168.0.254
nameserver 192.168.0.253

Troubleshoot a Slow Computer Network – Only One Computer on the Network is Slow

Only One Computer on the Network is Slow

Client Computer Network Mask Wrongly Configured
Your network is a class C network, (net-mask 255.255.255.0), and your client computer has its IP address configuration on a class B network, (255.255.0.0). Change the network mask of the client to match the network configuration.

Poor network cards
Bad network cards or bad drivers are very often the reason for poor transfer rates. Test the transfer rate with a different network card.
An outdated computer can also slow down your network transfer.

Bad Network Configuration
DNS Configuration
can be the cause a of slow network connections.
Wrong DNS address in the IP configuration can slow your network dramatically. Your DNS client will try to connect to an inexistent or not working DNS server then give up and try your secondary DNS server. This translates in slowdowns and sometimes even DNS resolution errors.
Fix: Ping the DNS address or, even better, use nslookup and connect to both of your DNS servers to check if they work.

The TCP/IP protocol stack corrupted.

Sometimes no matter what you do you can’t fix the network and this is because the TCP/IP becomes corrupted. The only thing that fixes it is a reset. On older Operating Systems, such as Windows 98 and Windows NT, the fix was to uninstall and reinstall the whole TCP/IP suite of protocols.
Fix: issue the following command to reset it: netsh int ip reset c:\resetlog.txt.

More Than One Default Route
Advanced Lan SettingsA very common mistake is to assign more than on default route to the same computer. Do not confuse load balancing with multiple Default Gateways. You are configuring two network cards, and both of them have a default gateway. This configuration will not work. Usually, a Windows computer will warn you that this is not a good idea, but some users will choose to ignore the warning.
This is a typical problem for laptop users, they connect into the Lan environment and leave the wireless connection on. This will create a lot of problems for corporate users and even for home users.
In order for this type of configuration to work, special routing rules and IP configuration is needed. it is easier to turn the wireless of or have an adapter manager that will automatically do that for you based on your rules.
Advanced Tcp/IP Settings
On a Windows XP there is a way to assign priorities to network cards using a graphic interface. from the Network Connections applet in the Control Panel, click on the Advanced menu and choose Advanced Settings.
On the Advanced Settings window arrange the network cards according to the correct priority.
Another way to achieve this is to change the gateway’s metric for each of the network adapters on the computer. To do this, open the TCP/IP properties on each of the network addapters with a default gateway configured, and click on the Advanced button. On the Advanced TCP/IP Settings window, uncheck the Automatic Metric for the Default Gateway, and enter a value according to your network topology. The lower the metric, the higher the preference for a default route.

This article is part of a five posts series regarding Network Troubleshooting.

Internet Marketing – 16 Ways to Get Back-links

Why is Backlinking important for Internet Marketing

Backlinks are incoming links to a website or web page.

Inbound links were once important as a primary means of web navigation;

Today their significance has diminished as the emergence of search engines changed the way WEB is accessed. Today, the importance of backlinks lies in search engine optimization (SEO). The number of backlinks is one indication of the popularity or importance of that website or page. Search Engines use backlinks as a parameter to determine the Page Rank of a webpage. They are still a source of traffic but is not as important as search results traffic direct traffic or advertising traffic.

Everybody has now recognized the importance of backlinking and it is an important aspect of the Internet Marketing. Some companies spend a lot of money trying to improve linking popularity and consequently Page Ranking.
There are various types of linking methods used by the Internet Marketers:

  • Reciprocal link
    Trade reciprocal links with other webmasters using a link exchange website or a script on your site. Reciprocal links do not carry the same weight as before, but it is still a good way to improve link popularity.
  • Article Marketing
    Article Marketing is a great way to obtain one-way links. Make sure you create a good resource box containing information about you and your website and attach that resource box to your articles. Distribute this to as many article directories as you can.
  • Forum signature linking
    Post on forums and share your knowledge. Create a signature that contains your website’s address. Posting on do-follow forums can be an efficient method. Do not spam forums, as this will blacklist your IP address, and your posts will be removed.
  • Blog comments
    Commenting on other’s webmasters’ blogs is an efficient way to get backlinks. Do not spam and post valuable comments that could benefit the community.
  • Image sharing
    (providing free quality images for a link-back)
  • Directory listing
    List your website to web-directories. DMOZ and Yahoo Directory are the two best ones and being listed here gives your site many points in rankings calculation.
  • Post press releases
    Underutilized method, great for a short time span popularity gain in Search Engines.
  • Blogging
    Very effective since you decide how many links you want to post on your blog, but can be time consuming.
  • Link-bait
    (Writing great article to which other webmaster will link to. Slow method for link building but is the most natural and provides the most stable back-links.)
  • Social Bookmarking
    The more bookmarked your site the better your rankings. Submit at the most popular Bookmarking sites and ask your friends to bookmark you.
  • Buying links from a web 2.0 site
    There are plenty of web sites that will sell you links. Beware that this is against the T.O.S. of search engines.
  • Video posting
    Posting videos to youtube, metacafe, etc… and attach your website’s link to it. This will not only provide you with a backlink, but will bring you traffic as well.
  • Social media links
    Links listed to Facebook or Twitter will convince Search Engines of the popularity of your page.
  • Create a WordPress plugin
    A great way to create back-links, but it is expensive. If you are a PHP programmer, and would like to start such a project, contact me.
  • Create a WordPress or Blogger template and give it free.
    A link to your website will be included in all of the websites that use your theme or template.
  • RSS publishing

As a rule for getting your backlinks, do not focus on one method. Use all of them because the diversity of links and link types will bring the value and will suggest Search Engines that the links are naturally built.

Link building won’t do anything for you if you don’t have content. There is no reason to conduct an Internet campaign for a website that doesn’t have any content.