Cheat sheet for Apache htaccess files.

# Enable Directory Browsing
Options +Indexes

## block a few types of files from showing
IndexIgnore *.wmv *.mp4 *.avi

# Disable Directory Browsing
Options All -Indexes

# Customize Error Messages
ErrorDocument 403 /forbidden.html
ErrorDocument 404 /notfound.html
ErrorDocument 500 /servererror.html

# Get SSI working with HTML/SHTML
AddType text/html .html
AddType text/html .shtml
AddHandler server-parsed .html
AddHandler server-parsed .shtml
# AddHandler server-parsed .htm

# Change Default Page (order is followed!)
DirectoryIndex myhome.htm index.htm index.php

# Block Users from accessing the site
<limit GET POST PUT>
order deny,allow
deny from 202.54.122.33
deny from 8.70.44.53
deny from .spammers.com
allow from all
</limit>
Allow only LAN users

order deny,allow
deny from all
allow from 192.168.0.0/24

# Redirect Visitors to New Page/Directory
Redirect oldpage.html http://www.domainname.com/newpage.html
Redirect /olddir http://www.domainname.com/newdir/

# Block site from specific referrers
RewriteEngine on
RewriteCond %{HTTP_REFERER} site-to-block.com [NC]
RewriteCond %{HTTP_REFERER} site-to-block-2.com [NC]
RewriteRule .* - [F]

# Block Hot Linking/Bandwidth hogging
RewriteEngine on
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http://(www.)?mydomain.com/.*$ [NC]
RewriteRule .(gif|jpg)$ - [F]

# Want to show a "Stealing is Bad" message too?
# Add this below the Hot Link Blocking code:
RewriteRule .(gif|jpg)$ http://www.mydomain.com/dontsteal.gif [R,L]

# Stop .htaccess (or any other file) from being viewed
<files file-name>
order allow,deny
deny from all
</files>
Avoid the 500 Error

# Avoid 500 error by passing charset
AddDefaultCharset utf-8
Grant CGI Access in a directory

Options +ExecCGI
AddHandler cgi-script cgi pl
# To enable all scripts in a directory use the following
# SetHandler cgi-script

# Change Script Extensions
AddType application/x-httpd-php .gne
# gne will now be treated as PHP files! Similarly, x-httpd-cgi for CGI files, etc.

# Use MD5 Digests
# Performance may take a hit but if thats not a problem, this is a nice option to turn on.

ContentDigest On

# The CheckSpelling Directive
CheckSpelling
# corrects simple spelling errors (for example, if someone forgets a letter or
# if any character is just wrong). Just add CheckSpelling On to
# your htaccess file.

# The ContentDigest Directive

# As the Apache core features documentation says: "This directive enables the
# generation of Content-MD5 headers as defined in RFC1864 respectively RFC2068.
# The Content-MD5 header provides an end-to-end message integrity check (MIC)
# of the entity-body. A proxy or client may check this header for detecting
# accidental modification of the entity-body in transit.

# Note that this can cause performance problems on your server since the message
# digest is computed on every request (the values are not cached). Content-MD5
# is only sent for documents served by the core, and not by any module.
# For example, SSI documents, output from CGI scripts, and byte range responses
# do not have this header."

# To turn this on, just add:

ContentDigest On

# Enable Gzip – Save Bandwidth

# BEGIN GZIP
<ifmodule mod_deflate.c>
# Combine the below two lines - I've split it up for presentation
AddOutputFilterByType DEFLATE text/text text/html text/plain text/xml text/css
  application/x-javascript application/javascript
</ifmodule>
# END GZIP

# Turn off magic_quotes_gpc

# Only if you use PHP
<ifmodule mod_php4.c>
php_flag magic_quotes_gpc off
</ifmodule>

# Set an Expires header and enable Cache-Control
<ifmodule mod_expires.c>
  ExpiresActive On
  ExpiresDefault "access plus 1 seconds"
  ExpiresByType text/html "access plus 7200 seconds"
  ExpiresByType image/gif "access plus 518400 seconds"
  ExpiresByType image/jpeg "access plus 518400 seconds"
  ExpiresByType image/png "access plus 518400 seconds"
  ExpiresByType text/css "access plus 518400 seconds"
  ExpiresByType text/javascript "access plus 216000 seconds"
  ExpiresByType application/x-javascript "access plus 216000 seconds"
</ifmodule>

<ifmodule mod_headers.c>
  # Cache specified files for 6 days
  <filesmatch ".(ico|flv|jpg|jpeg|png|gif|css|swf)$">
  Header set Cache-Control "max-age=518400, public"
  </filesmatch>
  # Cache HTML files for a couple hours
  <filesmatch ".(html|htm)$">
  Header set Cache-Control "max-age=7200, private, must-revalidate"
  </filesmatch>
  # Cache PDFs for a day
  <filesmatch ".(pdf)$">
  Header set Cache-Control "max-age=86400, public"
  </filesmatch>
  # Cache Javascripts for 2.5 days
  <filesmatch ".(js)$">
  Header set Cache-Control "max-age=216000, private"
  </filesmatch>
</ifmodule>