If your RPM based Linux System use proxy server to use internet(not connected internet directly), you cannot use "yum" commands by default.To Use yum commands to install packages via proxy internet, follow the below method.
Yum Behind Proxy
Step1: Edit yum.conf file located in /etc/yum.conf and specify the proxy server and port number,
and also apecify proxy username and password if required
[root@server ~#]vi /etc/yum.conf
Yum Behind Proxy
Step1: Edit yum.conf file located in /etc/yum.conf and specify the proxy server and port number,
and also apecify proxy username and password if required
[root@server ~#]vi /etc/yum.conf
#disable the line starting with "cachedir=/var/cache/yum/$basearch/$releasever"
by adding a "#" in front of the line. and add a new line just below and specify your internet proxy server ip address and port number in below format.(Reboot PC to take effect)
Use proxy_username and proxy_password (only if applicable)
Use proxy_username and proxy_password (only if applicable)
#cachedir=/var/cache/yum/$basearch/$releasever