Abra seu terminal
gedit .bashrc
adicione estas linhas,
export http_proxy="http://myusername:[email protected]:8080"
export https_proxy="https://myusername:[email protected]:8080"
fechar terminal, abrir novo terminal
sudo gedit /etc/apt/apt.conf
e adicione as seguintes linhas,
Acquire::http::Proxy "http://myusername:[email protected]:8080"
Acquire::https::Proxy "https://myusername:[email protected]:8080"
Acquire::socks::Proxy "socks://myusername:[email protected]:8080"
agora tente pingar no google
ping www.google.com
funcionará com certeza.