April, 2009
How to configure OSPF in the Cisco IOS
The OSPF dynamic routing protocol is probably the most popular LAN routing protocol today. OSPF can scale to the largest LANs but can also start out small. While OSPF can be complex to configure, its basic configuration isn’t difficult. Let’s learn how to configure OSPF in the Cisco IOS. To configure OSPF in the Cisco [...]
What do you need to know about OSPF?
OSPF stands for open shortest path first. It also uses the SPF (shortest path first) algorithm to determine the best route to its neighbors. OSPF is a standard routing protocol, as defined by RFC2328 and RFC1247. This means that OSPF can run on just about any company’s’ routers and OSPF routes from a non-Cisco router can be exchanged [...]
How to Configure Circular replication with four nodes with MySQL
Advanced MySQL Replication Techniques Having just two nodes could be what you need today, but as your application grows and you need to scale your database environment, you will need to add more nodes into the mix. It’s easy to extend this array to use four nodes Figure 2. Circular replication with four nodes In [...]
How to Set Up a Multimaster Replication System with Mysql
Advanced MySQL Replication Consider the situation where you set up a replication system with more than one master.One hard-to-solve problem in a multimaster replication is the conflict that can happen with self-generated keys. The AUTO_INCREMENT feature is quite convenient, but in a replication environment it will be disruptive. If node A and node B both [...]
How to Install Skype on Ubuntu
1. Go to System>Administration>Software Sources and enter your password 2. Under the Third Party tag click Add to add the skype repositry and in the text box that comes up, 3. Type (or paste) deb http://download.skype.com/linux/repos/debian/ stable non-free 4.  Allow the software to update its listings, and then open a terminal window 5.   Type “sudo [...]
How to reinstall ubuntu after the first installation fails
 What to do if an installation fails in Ubuntu If you stop an installation half-way through, a lock file is created that prevents you from installing anything else. Before you can try again you need to manually unlock the download cache. 1. Open a root terminal and type nautilus /var/cache/apt/archives 2. Right click on the file [...]
How to upgrade RoundCube Webmail
You’ve had RoundCube up and running for a while, and now there is a shiny new version out and you need to upgrade. Where to start? Download an Updated Version As with installation, you need to download the files for the newest version. The easiest way to get it is to visithttp://www.roundcube.net and click on “Downloads” or just [...]
How to Set up NFS Server in Ubuntu
NFS Server The first thing I need to do is set up the NFS server module on the server machine. 1. Type sudo apt-get install nfs-kernel-server 2. Type sudo dpkg-reconfigure portmap and it asks whether I want to bind to loopback and I select no. It then informs me I need to restart the service. 3. Restart using sudo /etc/init.d/portmap restart and [...]
How to Clean up unwanted files in Ubuntu
This is based on a tutorial found on the Ubuntu forums here and is a summary of the steps needed. For more explanation see the origina; 1. Go to System>Administation>Synaptic Package Manager 2. Click the Status button (bottom left) then click Residual config. 3. If anything comes up in the right hand window, select it and Mark for Complete Removal, [...]
How to Install Squid proxy server in Ubuntu
Squid is a proxy http server that speeds up getting pages from the internet by keeping copies of commonly accessed pages or graphics instead of downloading them each time. To install it:- 1. From a root terminal type apt-get install squid 2. Open gedit /etc/squid/squid.conf 3. Find the TAG: visible_hostname and after the comments section add visible_hostname <hostname> where <hostname> is your machine’s [...]
How to Limit the number of simultaneous Web connections from a client with maxconn ACL – Squid Proxy Server
You need to use squid ACCESS CONTROLS feature called maxconn. It puts a limit on the maximum number of connections from a single client IP address. It is an ACL that will be true if the user has more than maxconn connections open. It is used in http_access to allow/deny the request just like all [...]
A Brief on Cloud computing with Linux thin clients
Cloud computing has been covered extensively in a number of venues and from many points of view. For embedded Linux engineers and aficionados, one exciting aspect of cloud computing is the sudden interest in thin Linux clients. The basic concept of cloud computing is the use of resources accessed over the Internet. Combined with clients [...]
How to configure Wireless on CentOS System
Normally when we configure wireless card in GNU/Linux, I add some lines to the end of my rc.local to bring up the wireless interface, like this: iwconfig wlan0 essid cupotea iwconfig wlan0 mode Managed iwconfig wlan0 key xxxxxxxx ifconfig wlan0 10.0.0.10 netmask 255.255.255.0 ifconfig eth0 down ifconfig wlan0 up However, the correct way to do [...]
How to Create a PCAP packet capture on a J-Series Services Router
From time to time while trouble shooting, a packet capture is very useful. This is best accomplished by performing sniffer capture outside of the J-Series device. However there are instances where having a PC or server inline for Ethereal/Wireshark or tcpdump captures may not be possible. Therefore the J-Series Services Router can do a packet [...]