[racket] login to a site

i can access a site's page with get-pure-port (net/url).

how can i do the same for a site which requires my login info?

i see that there is a header field in get-pure-port, but don't know if
that's to be used. also, wouldn't i require some sort of session
tracking so that i can keep accessing pages on the site?

-- 
in friendship,
prad