Update Centos Linux 5.4 to Centos Linux 5.5

As you know, CentOS released version 5.5 and if you are using Centos Linux 5.4, you may actually upgrade it directly through your machine through the Internet with yum command.

To upgrade Centos version, you should take this 2 major steps.
1. Make a Backup.
2. Update package.

1. Make a backup
It is important to make a backup before you do any upgrade or installation. I will suggest you to have a full backup of your machine before doing the upgrade in case anything happen.

Make sure you have all of the data and database backup!

2. Update package
i) To upgrade your Centos, you may use yum command to upgrade it directly. However, you may try to check any update list available.
yum list updates

ii) You may update Centos as command below.
yum update

iii) Reboot your machine

iv) verify if everything working
uname -a
netstat -tulpn
tail -f /var/log/messages
cat /etc/redhat-release

How to Check Apache Connections

Apache is one of the famous web services and surpass for more than 100 Million website.

If you have experience in Server Administrator task, you surely headache on the Apache connections when it is getting tons of connections to the server. But, how could you going to check for those connections?

Some command like netstats, grep, ps, etc will very helpful to help you to understand the number of connections of the server.

Mick Genie will guide you some ways to list the Apache connection as below.

Grep port 80 (web services port)

netstat -alntp | grep :80

Check the number of connection from port 80

netstat -alntp | grep :80 | wc -l
ps auxw | grep httpd | wc -l

List the remote IPs connecting to your server on port 80

netstat -ntu | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -nr

List the unique remote IPs and the number of connections from each IP

netstat -alntp | grep :80 | awk ‘{print $5}’ | cut -d: -f1 | sort | uniq -c | sort -n