Using a proxy with apt-get

Temporary proxy session:
# export http_proxy=http://yourproxyaddress:proxyport

Permanently:
# sudo vi /etc/apt/apt.conf

Acquire::http::proxy "http://myproxy:80/";
Acquire::https::proxy "https://myproxy:80/";
Acquire::ftp::proxy "ftp://myproxy:80/";