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The basics of .htaccess file November 9, 2010

Posted by Tournas Dimitrios in Linux.

In this article you will find out about the .htaccess file and the power it has to improve your website. Although .htaccess is only a file, it can change settings on the servers and allow you to do many different things, the most popular being able to have your own custom 404 error pages. .htaccess isn’t difficult to use and is really just made up of a few simple instructions in a text file.

Will My Host Support It? This is probably the hardest question to give a simple answer to. Many hosts support .htaccess but don’t actually publicise it and many other hosts have the capability but do not allow their users to have a .htaccess file. As a general rule, if your server runs Unix or Linux, or any version of the Apache web server it will support .htaccess, although your host may not allow you to use it . A good sign of whether your host allows .htaccess files is if they support password protection of folders. To do this they will need to offer .htaccess (although in a few cases they will offer password protection but not let you use .htaccess). The best thing to do if you are unsure is to either upload your own .htaccess file and see if it works or e-mail your web host and ask them.

What Can I Do? You may be wondering what .htaccess can do, or you may have read about some of its uses but don’t realise how many things you can actually do with it. There is a huge range of things .htaccess can do including: password protecting folders, redirecting users automatically, custom error pages, changing your file extensions, banning users with certian IP addresses, only allowing users with certain IP addresses, stopping directory listings and using a different file as the index file.

Creating A .htaccess File Creating a .htaccess file may cause you a few problems. Writing the file is easy, you just need enter the appropriate code into a text editor (like notepad). You may run into problems with saving the file. Because .htaccess is a strange file name (the file actually has no name but a 8 letter file extension) it may not be accepted on certain systems (e.g. Windows 3.1). With most operating systems, though, all you need to do is to save the file by entering the name as: “.htaccess” (including the quotes). If this doesn’t work, you will need to name it something else (e.g. htaccess.txt) and then upload it to the server. Once you have uploaded the file you can then rename it using an FTP program.
Warning : Before beginning using .htaccess, I should give you one warning. Although using .htaccess on your server is extremely unlikely to cause you any problems (if something is wrong it simply won’t work), you should be wary if you are using the Microsoft FrontPage Extensions. The FrontPage extensions use the .htaccess file so you should not really edit it to add your own information. If you do want to (this is not recommended, but possible) you should download the .htaccess file from your server first (if it exists) and then add your code to the beginning.
Custom Error Pages : The first use of the .htaccess file which I will cover is custom error pages. These will allow you to have your own, personal error pages (for example when a file is not found) instead of using your host’s error pages or having no page. This will make your site seem much more professional in the unlikely event of an error. It will also allow you to create scripts to notify you if there is an error (for example I use a PHP script on Free Webmaster Help to automatically e-mail me when a page is not found). You can use custom error pages for any error as long as you know its number (like 404 for page not found) by adding the following to your .htaccess file:  ErrorDocument errornumber /file.html
For example if I had the file notfound.html in the root directory of my site and I wanted to use it for a 404 error I would use: ErrorDocument 404 /notfound.html
If the file is not in the root directory of your site, you just need to put the path to it:  ErrorDocument 500 /errorpages/500.html
These are some of the most common errors:
401 – Authorization Required
400 – Bad request
403 – Forbidden
500 – Internal Server Error
404 – Wrong page
Then, all you need to do is to create a file to display when the error happens and upload it and the .htaccess file.

Stop A Directory Index From Being Shown : Sometimes, for one reason or another, you will have no index file in your directory. This will, of course, mean that if someone types the directory name into their browser, a full listing of all the files in that directory will be shown. This could be a security risk for your site. To prevent against this (without creating lots of new ‘index’ files, you can enter a command into your .htaccess file to stop the directory list from being shown: Options -Indexes
Deny/Allow Certian IP Addresses : In some situations, you may want to only allow people with specific IP addresses to access your site (for example, only allowing people using a particular ISP to get into a certian directory) or you may want to ban certian IP addresses (for example, keeping disruptive memembers out of your message boards). Of course, this will only work if you know the IP addresses you want to ban and, as most people on the internet now have a dynamic IP address, so this is not always the best way to limit usage.
You can block an IP address by using: deny from where is the IP address. If you only specify 1 or 2 of the groups of numbers, you will block a whole range.
You can allow an IP address by using: allow from where is the IP address. If you only specify 1 or 2 of the groups of numbers, you will allow a whole range.
If you want to deny everyone from accessing a directory, you can use:  deny from all but this will still allow scripts to use the files in the directory.

Alternative Index Files : You may not always want to use index.htm or index.html as your index file for a directory, for example if you are using PHP files in your site, you may want index.php to be the index file for a directory. You are not limited to ‘index’ files though. Using .htaccess you can set foofoo.blah to be your index file if you want to!
Alternate index files are entered in a list. The server will work from left to right, checking to see if each file exists, if none of them exisit it will display a directory listing (unless, of course, you have turned this off).
DirectoryIndex index.php index.php3 messagebrd.pl index.html index.htm

Redirection : One of the most useful functions of the .htaccess file is to redirect requests to different files, either on the same server, or on a completely different web site. It can be extremely useful if you change the name of one of your files but allow users to still find it. Another use (which I find very useful) is to redirect to a longer URL, for example in my newsletters I can use a very short URL for my affiliate links. The following can be done to redirect a specific file: Redirect /location/from/root/file.ext http://www.othersite.com/new/file/location.xyz
In this above example, a file in the root directory called oldfile.html would be entered as: /oldfile.html and a file in the old subdirectory would be entered as: /old/oldfile.html
You can also redirect whole directoires of your site using the .htaccess file, for example if you had a directory called olddirectory on your site and you had set up the same files on a new site at: http://www.newsite.com/newdirectory/ you could redirect all the files in that directory without having to specify each one: Redirect /olddirectory http://www.newsite.com/newdirectory
Then, any request to your site below /olddirectory will bee redirected to the new site, with the  extra information in the URL added on, for example if someone typed in:

They would be redirected to: http://www.newsite.com/newdirectory/oldfiles/images/image.gif
This can prove to be extremely powerful if used correctly.

Password protection :Although there are many uses of the .htaccess file, by far the most popular, and probably most useful, is being able to relaibly password protect directories on websites. Although JavaScript etc. can also be used to do this, only .htaccess has total security (as someone must know the password to get into the directory, there are no ‘back doors’) Adding password protection to a directory using .htaccess takes two stages. The first part is to add the appropriate lines to your .htaccess file in the directory you would like to protect. Everything below this directory will be password protected:
AuthName “Section Name”
AuthType Basic
AuthUserFile /full/path/to/.htpasswd
Require valid-user
There are a few parts of this which you will need to change for your site. You should replace “Section Name” with the name of the part of the site you are protecting e.g. “Members Area”. The /full/parth/to/.htpasswd should be changed to reflect the full server path to the .htpasswd file (more on this later). If you do not know what the full path to your webspace is, contact your system administrator for details.
The .htpasswd File: Password protecting a directory takes a little more work than any of the other .htaccess functions because you must also create a file to contain the usernames and passwords which are allowed to access the site. These should be placed in a file which (by default) should be called .htpasswd. Like the .htaccess file, this is a file with no name and an 8 letter extension. This can be placed anywhere within you website (as the passwords are encrypted) but it is advisable to store it outside the web root so that it is impossible to access it from the web.
Entering Usernames And Passwords :Once you have created your .htpasswd file (you can do this in a standard text editor) you must enter the usernames and passwords to access the site. They should be entered as follows: username:password where the password is the encrypted format of the password. To encrypt the password you will either need to use one of the premade scripts available on the web or write your own. There is a good username/password service at the KxS site which will allow you to enter the user name and password and will output it in the correct format.
For multiple users, just add extra lines to your .htpasswd file in the same format as the first. There are even scripts available for free which will manage the .htpasswd file and will allow automatic adding/removing of users etc.
Accessing The Site : When you try to access a site which has been protected by .htaccess your browser will pop up a standard username/password dialog box. If you don’t like this, there are certain scripts available which allow you to embed a username/password box in a website to do the authentication. You can also send the username and password (unencrypted) in the URL as follows: http://username:password@www.website.com/directory/
Summary : .htaccess is one of the most useful files a webmaster can use. There are a wide variety of different uses for it which can save time and increase security on your website.


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