First we need to setup the default connection settings. Go to the menu bar and click on System settings -> network settings. Click on the Proxy section and select “Use manually specified proxy configuration”.
Set the following params depending your proxy configuration:

Configure Environment variables

Some applications usually use the environment variables to connect to internet. So we need to add the proxy to the environment variables as well. We can run the following commands in the console to have it working for this session:

export http_proxy="http://YourProxyAddress:YourProxyPortNumber"
export https_proxy="http://YourProxyAddress:YourProxyPortNumber"
export ftp_proxy="http://YourProxyAddress:YourProxyPortNumber"

But after restarting the computer the variables will be gone. So I recommend to add the environment variables permanently. We just need to go the folder env.d folder:

cd /etc/env.d

Add the file 99local if it doesn’t exist already.

sudo touch 99local

Edit the file

sudo nano 99local

Add the environment variables to the file

http_proxy="http://YourProxyAddress:YourProxyPortNumber"
https_proxy="http://YourProxyAddress:YourProxyPortNumber"
ftp_proxy="http://YourProxyAddress:YourProxyPortNumber"

Now we need to update the environment variables

sudo env-update

We can check if it worked by logging back in the shell and running the following command:

sudo echo $http_proxy

It should return the proxy server address, if it’s still empty try running the following command and try to print the proxy again:

sudo env-update && source /etc/profile
sudo echo $http_prox

Configure Equo (Entropy system)

If after following all the previous steps Equo is still not able to find the repositories, edit entropy.conf.

sudo nano /etc/entropy/entropy.conf  

Search for http proxy configuration and modify the http-proxy and ftp-proxy.

ftp-proxy = http://YourProxyAddress:YourProxyPortNumber
http-proxy = http://YourProxyAddress:YourProxyPortNumber