Install Packages via yum using CentOS Media repo

when need to install new packages using yum, you can use either online repo or dvd repo. If there is no internet connection, possible solution is DVD repo. Here is simple way to configure DVD repo on Centos.

1) View Centos media repo file.

Since I use Centos 6.3 it is similar to following.you can use either less or cat command to view the file content. Some  lines are removed due to brevity

less /etc/yum.repos.d/CentOS-Media.repo
[c6-media]
name=CentOS-$releasever - Media
baseurl=file:///media/CentOS/
        file:///media/cdrom/
        file:///media/cdrecorder/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

give more attention to following parameters
repo name -> c6-media
baseurl -> there is 3 file paths, those are the mount point of Centos DVD. you can customize it.

2) Create mount point if not exist

since this is demo, I create DVD mount location as first base URL. possible use any location which is defined in baseurl.
[root@localhost ~]# mkdir /media/CentOS

3) mount centos cdrom

mount /dev/cdrom /media/CentOS/

4)Install your package using yum

yum --disablerepo=\* --enablerepo=[repo name] install [pakage name]

ex:-
yum --disablerepo=\* --enablerepo=c6-media install cpan

if this is not working, you may need to clean repo using following command
[root@localhost ~]# yum clean all

Prevent SSH connection from freezing

Recently I have experinced my ssh connection to remote server is hung after idle time. this is very annoying because ssh connection was established over vpn and take time to reconnect the session again. If your ssh connection hung/freeze time to time following solution may be helpful.

1) Open the ssh_config file.

location may differ,in centos
vim /etc/ssh/ssh_config

2) Add following lines

Host *
    ServerAliveInterval 300
    ServerAliveCountMax 2


Remember, this configuration is done at client side. client send keep alive message to server every 180 seconds and server send ack (acknowledgement) message.If 2 consecutive ack messages are lost from server side. connection will be dropped as server is not available.