I failed to rsync files from one Centos 6 server to another Centos 6 server. The rsync is not working and i get this error

[root@angrybird tmp]# rsync -v -e ssh /tmp/web root@172.16.0.204:/home/
rsync: Failed to exec ssh: No such file or directory (2)
rsync error: error in IPC code (code 14) at pipe.c(84) [sender=3.0.6]
rsync: connection unexpectedly closed (0 bytes received so far) [sender]
rsync error: error in rsync protocol data stream (code 12) at io.c(600) [sender=3.0.6]

To troubleshoot this issue, i try to do run ssh command in both Centos 6 machine. It fail to run the SSH. I found that openssh-clients was not installed. So, i just installed openssh-clients to fix the problem.

To install openssh-client

# yum -y install openssh-clients

Done!!

Your DNS cache stores the locations (IP addresses) of pages you have recently viewed. DNS cache help to speeds up the lookups within the same host.  But sometimes if the website page change before your DNS cache is updated, you will failed to access the page. For example, you received a web page with HTML 404 error codes. So you need to flush your DNS cache. Once you clear your DNS cache, your computer will query nameservers for the new DNS information you require.

Clear DNS cache on Windows XP, Vista, Win7

1. Open the Start menu.
2. Go to Run.
   • If you do not see the Run command in Vista, search for “run” in the Search bar.
3. In the Run text box, type: ipconfig /flushdns
4. Press Enter or Return, and your cache will be flushed.

To clear DNS cache in Mac OS X 10.5 and above, use the following command:

1. Go to Applications.
2. Go to Utilities.
3. Open the Terminal application.
4. Type: dscacheutil -flushcache
5. Press Enter or Return, and your cache will be flushed.

Clear DNS cache on Linux (Red Hat / Fedora / CentOS)

Launch your terminal and enter following command to flush DNS:-

$ sudo /etc/init.d/nscd restart

OR

# service nscd restart

First thing that you need to do after installed Centos 6  is to make changes to Network configuration such as assign IP address, change DNS server etc.

To do that, just log on as root and change directory to /etc/sysconfig/network-scripts/ to view all available devices.

# cd /etc/sysconfig/network-scripts/

You need to edit following files:

• /etc/sysconfig/network-scripts/ifcfg-eth0 : First Ethernet card configuration file
• /etc/sysconfig/network-scripts/ifcfg-eth1 : Second Ethernet card configuration file

To edit/create first NIC file, type command:

# vi ifcfg-eth0

Append/modify as follows:

DEVICE=eth0
BOOTPROTO=static
DHCPCLASS=
HWADDR=00:30:48:56:A6:2E
IPADDR=192.168.0.10
NETMASK=255.255.255.0
ONBOOT=yes


Save and close the file.

After that, configure the default gateway (router IP) and hostname in /etc/sysconfig/network file:

# vi /etc/sysconfig/network

Append/modify configuration as follows:

NETWORKING=yes
HOSTNAME=techkaki
GATEWAY=192.168.0.1


Save and close the file. Restart networking by enter following command:

# /etc/init.d/network restart

Make sure you have correct DNS server defined in /etc/resolv.conf file:

# vi /etc/resolv.conf

Setup DNS Server as follows:

nameserver 8.8.8.8
nameserver 8.8.4.4
nameserver 202.67.222.222

Save and close the file. Now you can ping the gateway/other hosts:

$ ping 192.168.0.1

I just installed Apache web server on my Fedora 15 system. After starting HTTP (Apache web server) in Linux & pointing your web browser to http://localhost, you will see below test page. This means your server has configures & ready to use.

Question: Is it anyway to remove this Apache Test Page?

Answer: Yes, you can disable this page if you don’t want it.

To remove apache test page in CentOS/REHL/Fedora, follow the steps below:-

• Start your Terminal and login to your web server thru SSH
• Once logged in, enter following command to remove the test page (Pls make sure you login as root)

[root@www ~]# rm -f /etc/httpd/conf.d/welcome.conf

[root@www ~]# rm -f /var/www/error/noindex.html

• now reload your apache web server

[root@www ~]# service httpd reload

Now  try to open your browser and enter http://localhost.  You shouldn’t see any Apache Test Page again.

I wanted to install phpmyadmin on Centos 5.6 Machine. I check from phpmyadmin official web site, phpmyadmin requires at least PHP 5.2 and MySQL 5. I have to check my php version 1st before start install.

Here is a useful command to display or show what version of php you have installed in your Linux Machine.

Just enter following command to check your PHP Version

root@raptor(~)
[ 2]# php -v
PHP 5.1.6 (cli) (built: Nov 29 2010 16:47:46)
Copyright (c) 1997-2006 The PHP Group
Zend Engine v2.1.0, Copyright (c) 1998-2006 Zend Technologies

Once you enter the php -v command, you should able to see the result like what i show you above, if you don’t get something like the above, then it means that you don’t have php installed in your server.

Recently, I just install my new CentOS 5.6.(CentOS is the open source equivalent to the Red Hat Linux operating system). I want to setup LAMP on my Centos 5.6 as my development environment to customize my wordpress theme. I will install the LAMP using yum command.

Here are the simple steps:-

Before start the installation, please ensure that all of your repositories and packages are up to date.

yum check-update

yum update

I noticed that my Centos Server logs is not on the correct time. I tried to check the time from the command line and found that the timezone is pointing to the wrong timezone

root@thundercat ~]# date
Mon May 23 00:21:56 EDT 2011

How to change it? There are two ways to change the timezone on CentOS.

1. Set the timezone by running system-config-date command

Type the system-config-date command at the command line to start the time and date properties tool. After that, just follow on screen instructions to change timezone.

2. Set timezone using /etc/localtime configuration file

It is very easy to change the Timezone from /etc/localtime. Just create a new soft link for /etc/localtime to /usr/share/zoneinfo (directory contains the time zone files)

Below are the steps to do it:-

• Just make a backup of the existing localtime file

mv /etc/localtime /etc/localtime.bak

• Create a new soft link for /etc/localtime

ln -s /usr/share/zoneinfo/Asia/Kuala_Lumpur /etc/localtime

• To test your change. Run the “date” command to ensure that the appropriate time, date, and timezone are reported.

[root@thundercat ~]# date
Mon May 23 12:23:27 MYT 2011

Below are the few steps :-

1) Open /etc/hosts.allow

Use the following command to open the hosts.allow file:

Once this file is open, add the following line:

2) Open /etc/hosts.deny

Use the following command to open the hosts.deny file:

Once it opens, add the following line to the file:

Save and exit, and you have successfully limited SSH access by IP address.

Latest version of Centos (Centos 5.6) has been released and it available for download.

Below are the major changes in Centos 5.6

The CentOS team is pleased to announce the availability of CentOS 5.6. Major changes in CentOS 5.6 compared to CentOS 5.5 include:

ext4 is now a fully supported file system
libvirt was updated to 0.8.2
bind was updated to 9.7 and supports NSEC3 now.
ebtables was added
php53 is available as a php replacement.
System Security Services Daemon (SSSD) has been added.

Other upgrades include newer version of several wireless drivers, Samba3x, ghostscript, LVM, mod_nss, subversion and gcc, plus others.

To download Cents 5.6 image, click HERE to download

Besides, Centos 5.6 also available via mirrors for immediate update. You can use yum command to upgrade your Centos to latest Centos 5.6.

Below are the steps that i use to upgrade my Centos 5.5 to Cento 5.6

Step 1: Backup your Data

• Before you start do any upgrade, please do a backup for your system to prevent any data lost or corrupt.

Step 2: Type the following command to update and upgrade your Centos 5.5

[root@baggies ~]# yum clean all

[root@baggies ~]# yum update glibc\*

[root@baggies ~]# yum update yum\* rpm\* python\*

[root@baggies ~]# yum clean all

[root@baggies ~]# yum update -y

Step 3: To verify your upgrade, just enter the following command

[root@baggies ~]# cat /etc/redhat-release

CentOS release 5.6 (Final)

Step 4: Reboot your Server

It is easy to update your SSH via yum. To do so, simply SSH into your linux server. Once logged in, type the the following;

#yum update openssh

This will update the openssh process, openssh-clients and openssh-server.

To verify what version of openssh you are running, you can type the following commend;

#ssh -V

Your server will then reply back with the version;

[root@XXXXXXX ~]# ssh -V
OpenSSH_4.3p2, OpenSSL 0.9.8e-fips-rhel5 01 Jul 2008