Check the configuration section in the CPAN module documentation (perldoc CPAN).

There's also a section regarding CPAN and firewalls.

In a nutshell, you can define your own $HOME/.cpan/CPAN/MyConfig.pm where you can specify a proxy for your HTTP requests.

You should also be able to set the http_proxy environment variable to instruct CPAN to use it. Moreover, many HTTP proxies also act as FTP proxies, so you might want to try with ftp_proxy too.

Anyway, check the documentation and you'll find many ways (there's more than one way to do it, even when configuring) to access CPAN behind a firewall.

Happy {perl -MCPAN -eshell}ing!

-- TMTOWTDI