How to setup Proxy configuration in Linux

What is proxy?
      A proxy is another computer which serves as a middle through which internet requests are processed. Proxy servers give enhanced performance plus security. 
      Here the following methods are provided to configure the proxy settings

METHOD 1

Edit the file /etc/environment

And then add the following lines after PATH=" something here"

http_proxy=http://<IP-or-DNS-name>:<port-number>

(or)

http_proxy=http://<user-name>:<password>@<IP-or-DNS-name>:<port-number>

To access ftp based sites via Proxy

ftp_proxy=ftp://<IP-or-DNS-name>:<port-number>

(or)

ftp_proxy=ftp://<user-name>:<password>@<IP-or-DNS-name>:<port-number>

To access secure https sites via proxy

https_proxy=http://<IP-or-DNS-name>:<port-number>

(or)

https_proxy=https://<user-name>:<password>@<IP-or-DNS-name>:<port-number>

Reminder: If your password contains @, it should be replaced by %40. For example: If your password is blog@123 then it should be given as blog%40123

  

METHOD 2

Using Command Line also, the proxy can be configured. And also note that this not suited for permanent connection

Syntax : export http_proxy=http://<IP-or-DNS-name>:<port-number>

(or)

Syntax : export https_proxy=http://<user-name>:<password>@<IP-or-DNS-name>:<port-number> 

To access ftp based sites via Proxy

Syntax : export ftp_proxy=http://<IP-or-DNS-name>:<port-number>

(or)

Syntax : export ftp_proxy=http://<user-name>:<password>@<IP-or-DNS-name>:<port-number>

To access secure https sites via proxy

Syntax : export https_proxy=http://<IP-or-DNS-name>:<port-number>

(or)

Syntax : export https_proxy=http://<user-name>:<password>@<IP-or-DNS-name>:<port-number>

METHOD 3

Proxy Settings in APT on Ubuntu Linux

sudo nano  /etc/apt/apt.conf

Acquire::http::Proxy "http://<IP-or-DNS-name>:<port-number>";

METHOD 4 

Configure proxy on YUM (yellow dog updater) package manager

yum proxy settings can be found in the file system at

sudo nano /etc/yum.conf

Add a line to the file with the following information:

proxy=http://<IP-or-DNS-name>:<port-number>