Databases, Systems & Networks

If you are running the Apache Web Server or your web hosting provider running Apache based web server, you can use .htaccess configuration file to restrict access to your website. This could be a very important issue from security stand point of view especially if your server is being attacked or hacked from any specific or range of IP addresses.

Now, restricting access method works in two ways. First, you can restrict access to certain IP addresses and allow others. Second, you can restrict access to everyone but few IP addresses only. On this post, I will focus on both method and will try to explain as much as I can.

Restrict Certain IP Addresses

If you want to restrict specific IP addresses from accessing your site, you can use the following lines on your .htaccess file.

order deny,allow
deny from 123.4.5.6
deny from 654.3.2.1
allow from all

These lines above will block “123.4.5.6” and “654.3.2.1” IP addresses from accessing your site. You can add as many IP addresses as you want on this “deny from” list. One interesting fact is, Apache web server gives you lot more flexibility in terms of blocking IP addresses. Take a look at the following lines.

order deny,allow
deny from 123.4.5.
allow from all

If you observe it carefully, you will see that the fourth set of digit is missing on this IP address. It means, if any IP address that matches the first three set of digits will be blocked. So basically anyone with IP address like “123.4.5.1” or “123.4.5.244” won’t be able to access your site as in both IP address matches with the first three (123.4.5.) sets of digits blocked by the Apache web server.

Allow Specific IP Addresses

Think of about a site that you built for a very specific purpose and for very few people, where you do not want everyone to show up. Apache allows you to do that as well.

For an example, lets assume that you built a site that you want one of your friend to be able to access and his IP address is “123.4.5.12”. Simply write the following line on your .htaccess file and you are good to go.

order allow,deny
allow from 123.4.5.12
deny from all

In this case Apache will block all IP addresses except your friends IP address. This is as simple as it can get and I hope you got the basic idea.

Note: On all of my example I used either “allow from all” or “deny from all” at the bottom, this is very important. You must declare either one of these line based on your requirement or things might get little more complicated.

Also remember that all blocked IP addresses would be forwarded or shown an “403 Forbidden” error message. You can definitely customize this message as well but that’s something I will talk about in another post.

Source: iftekhar.net