Building ports with sorces on a local mirror?

[stan]

I'm in the process of seting up to build a fair number of machines behind a
very restrictive firewall (and besides that the outbound link is very
slow).

What I have in mind is setting up a machine using mirror software to create
a local mirror of the FreeBSD site, including the distfiles for the ports
tree.

Is thee a way to get the ports build system to look for distfiles on this
local mirror?

-- 
Unix is very simple, but it takes a genius to understand the simplicity.
(Dennis Ritchie)