How to access a server http port 80 with port forwarding behind a router but require a password

[leegold at speedymail.org]

Hi,

Using Ubuntu 10.04 LTS.

I have an intranet server behind a NAT router. Very standard linksys
router home setup. The server has a static IP. I used port forwarding in
the router to use SSH and log into the server remotely - it works OK.

I want no one outside my home network to access any webpages on the
server unless they're authenticated.. I know I could port forward like
with ssh but with http port 80 and then see webpages , but again this
would open it up to anyone with my cable modem's IP - wouldn't it?

I need a secure way like SSH that requires a password before anyone
could access port 80 and http from the server from a remote network.

How do I do this? And on the local network people can get served pages
normally as usual. Just remote would need authentication. Must be
commonly done(?)

Thanks,

Lee G.