I've a credit card applicatoin installed say at http://gwmubiru.com/login.php.

I wish to send this as demo to various potential clients. I wish to have the ability to grant and /or deny use of clients. I'd rather not setup each client like a user within the database since my demos have several user type I wish to demo.

It is possible to method to control access might be using Apache, htaccess as well as linux?

You should use http Authentication.

http://httpd.apache.org/docs/2.0/howto/auth.html

You create several customers/passwords and provide someone to all of your customers. You then remove their access.

You are right, you have options:

From Apache, most likely the simplest mechanism is mod_authz_host:

Allow from apache.org
Allow from .net example.edu

It really works both in <directory> and htaccess files, so it may be simplest.

If you wish to limit use of your whole webserver, you are able to certainly add firewall rules that will permit only your customers to gain access to it. This can be just a little anti-social, but when you'd enjoy only your customers and prospects to ever begin to see the demo system, firewalling can perform that.

The [cde] tool could make adding firewall rules pretty easy you should check it out if you are very a new comer to firewalling.

ufw

If you wish to find out more about IPTables, then you definitely might fare better just missing past sudo ufw allow from 192.168.0.4 to any port 80 . It has been some time since I have set up IPTables (and I am afraid I'll don't know it too as OpenBSD's [cde] firewall). Be sure to leave yourself an ufw path to your server, and think about using the [cde] script to check changes on remote systems. (We have all locked ourselves from our servers sooner or later, just don't create a practice of it.)