Most Useful and Helpful .htaccess Code

.htaccess

#stop directory browsing
Options All -Indexes

# SSL Https active Force non-www
<IfModule mod_rewrite.c>
   RewriteEngine on
   RewriteCond %{HTTP_HOST} ^www\.(.*)$ [NC]
   RewriteRule ^(.*)$ https://%1/$1 [R=301,L]
   RewriteCond %{HTTPS} !=on
   RewriteRule ^(.*)$ https://%{HTTP_HOST}/$1 [R=301,L]
</IfModule>

# SSL Https Active Force www in a Generic Way
<IfModule mod_rewrite.c>
   RewriteEngine on
   RewriteCond %{HTTP_HOST} !^$
   RewriteCond %{HTTP_HOST} !^www\. [NC]
   RewriteCond %{HTTPS}s ^on(s)|
   RewriteRule ^ https://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]
</IfModule>


# Remove .php, .html, .htm extensions with .htaccess
<IfModule mod_rewrite.c>
    
    # domain.com/page
    RewriteEngine On
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteRule ^([^\.]+)$ $1.php [NC,L]
   
    
    # domain.com/page/
    RewriteEngine On
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteRule ^([^/]+)/$ $1.php
    RewriteRule ^([^/]+)/([^/]+)/$ /$1/$2.php
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteCond %{REQUEST_URI} !(\.[a-zA-Z0-9]{1,5}|/)$
    RewriteRule (.*)$ /$1/ [R=301,L]
    
</IfModule>


#AIOWPS_PREVENT_IMAGE_HOTLINKS_START
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{REQUEST_FILENAME} -f
RewriteCond %{REQUEST_FILENAME} \.(gif|jpe?g?|png)$ [NC]
RewriteCond %{HTTP_REFERER} !^http(s)?://univahost\.com [NC]
RewriteRule \.(gif|jpe?g?|png)$ - [F,NC,L]
</IfModule>
#AIOWPS_PREVENT_IMAGE_HOTLINKS_END


# Text FIle access
<files file.txt>
order allow,deny
deny from all
</files>


# Block double extensions from being uploaded or accessed, including htshells
<FilesMatch ".*\.([^.]+)\.([^.]+)$">
Order Deny,Allow
Deny from all
</FilesMatch>

# secure uploads directory
<FilesMatch "\.(jpg|jpeg|jpe|gif|png|tif|tiff)$">
    Order Deny,Allow
    Allow from all
</FilesMatch>


# Block shell uploaders, htshells, and other baddies
RewriteCond %{REQUEST_URI} ((php|my|bypass)?shell|remview.*|phpremoteview.*|sshphp.*|pcom|nstview.*|c99|c100|r57|webadmin.*|phpget.*|phpwriter.*|fileditor.*|locus7.*|storm7.*)\.(p?s?x?htm?l?|txt|aspx?|cfml?|cgi|pl|php[3-9]{0,1}|jsp?|sql|xml) [NC,OR]
RewriteCond %{REQUEST_URI} (\.exe|\.php\?act=|\.tar|_vti|afilter=|algeria\.php|chbd|chmod|cmd|command|db_query|download_file|echo|edit_file|eval|evil_root|exploit|find_text|fopen|fsbuff|fwrite|friends_links\.|ftp|gofile|grab|grep|htshell|\ -dump|logname|lynx|mail_file|md5|mkdir|mkfile|mkmode|MSOffice|muieblackcat|mysql|owssvr\.dll|passthru|popen|proc_open|processes|pwd|rmdir|root|safe0ver|search_text|selfremove|setup\.php|shell|ShellAdresi\.TXT|spicon|sql|ssh|system|telnet|trojan|typo3|uname|unzip|w00tw00t|whoami|xampp) [NC,OR]
RewriteCond %{QUERY_STRING} (\.exe|\.tar|act=|afilter=|alter|benchmark|chbd|chmod|cmd|command|cast|char|concat|convert|create|db_query|declare|delete|download_file|drop|edit_file|encode|environ|eval|exec|exploit|find_text|fsbuff|ftp|friends_links\.|globals|gofile|grab|insert|localhost|logname|loopback|mail_file|md5|meta|mkdir|mkfile|mkmode|mosconfig|muieblackcat|mysql|order|passthru|popen|proc_open|processes|pwd|request|rmdir|root|scanner|script|search_text|select|selfremove|set|shell|sql|sp_executesql|spicon|ssh|system|telnet|trojan|truncate|uname|union|unzip|whoami) [NC]
RewriteRule .* - [F]



# Follow symbolic links in this directory.
Options +FollowSymLinks

# Set the default handler.
DirectoryIndex index.php index.html index.htm

# Set the default handler.
DirectoryIndex index.php index.html index.htm

# Override PHP settings that cannot be changed at runtime. See
# sites/default/default.settings.php and drupal_environment_initialize() in
# includes/bootstrap.inc for settings that can be changed at runtime.

# PHP 5, Apache 1 and 2.
<IfModule mod_php5.c>
  php_flag magic_quotes_gpc                 off
  php_flag magic_quotes_sybase              off
  php_flag register_globals                 off
  php_flag session.auto_start               off
  php_value mbstring.http_input             pass
  php_value mbstring.http_output            pass
  php_flag mbstring.encoding_translation    off
</IfModule>

# Default Carset
AddDefaultCharset utf-8
DirectoryIndex index.html index.htm index.php

# File Control
<FilesMatch ".(flv|gif|jpg|jpeg|png|ico|swf|js|css|pdf)$">
  Header set Cache-Control "max-age=2592000"
</FilesMatch>

# Htaccess File Security
<Files .htaccess>
order allow,deny
deny from all
</Files>


# Adding this to your .htaccess will prevent hotlinking from happening:
RewriteEngine on
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http(s)?://(www\.)?YourDomain [NC]
RewriteRule \.(jpg|jpeg|png|gif)$ - [NC,F,L]


# Protect the .htaccess Itself
<files ~ "^.*\.([Hh][Tt][Aa])">
order allow,deny
deny from all
satisfy all
</files>

 
# Leverage Browser Caching
<IfModule mod_expires.c>
  ExpiresActive On
  ExpiresByType image/jpg "access 1 year"
  ExpiresByType image/jpeg "access 1 year"
  ExpiresByType image/gif "access 1 year"
  ExpiresByType image/png "access 1 year"
  ExpiresByType text/css "access 1 month"
  ExpiresByType text/html "access 1 month"
  ExpiresByType application/pdf "access 1 month"
  ExpiresByType text/x-javascript "access 1 month"
  ExpiresByType application/x-shockwave-flash "access 1 month"
  ExpiresByType image/x-icon "access 1 year"
  ExpiresDefault "access 1 month"
</IfModule>
<IfModule mod_headers.c>
  <filesmatch "\.(ico|flv|jpg|jpeg|png|gif|css|swf)$">
  Header set Cache-Control "max-age=2678400, public"
  </filesmatch>
  <filesmatch "\.(html|htm)$">
  Header set Cache-Control "max-age=7200, private, must-revalidate"
  </filesmatch>
  <filesmatch "\.(pdf)$">
  Header set Cache-Control "max-age=86400, public"
  </filesmatch>
  <filesmatch "\.(js)$">
  Header set Cache-Control "max-age=2678400, private"
  </filesmatch>
</IfModule>




# Enable Compression
<IfModule mod_deflate.c>
  AddOutputFilterByType DEFLATE application/javascript
  AddOutputFilterByType DEFLATE application/rss+xml
  AddOutputFilterByType DEFLATE application/vnd.ms-fontobject
  AddOutputFilterByType DEFLATE application/x-font
  AddOutputFilterByType DEFLATE application/x-font-opentype
  AddOutputFilterByType DEFLATE application/x-font-otf
  AddOutputFilterByType DEFLATE application/x-font-truetype
  AddOutputFilterByType DEFLATE application/x-font-ttf
  AddOutputFilterByType DEFLATE application/x-javascript
  AddOutputFilterByType DEFLATE application/xhtml+xml
  AddOutputFilterByType DEFLATE application/xml
  AddOutputFilterByType DEFLATE font/opentype
  AddOutputFilterByType DEFLATE font/otf
  AddOutputFilterByType DEFLATE font/ttf
  AddOutputFilterByType DEFLATE image/svg+xml
  AddOutputFilterByType DEFLATE image/x-icon
  AddOutputFilterByType DEFLATE text/css
  AddOutputFilterByType DEFLATE text/html
  AddOutputFilterByType DEFLATE text/javascript
  AddOutputFilterByType DEFLATE text/plain
</IfModule>

<IfModule mod_gzip.c>
  mod_gzip_on Yes
  mod_gzip_dechunk Yes
  mod_gzip_item_include file .(html?|txt|css|js|php|pl)$
  mod_gzip_item_include handler ^cgi-script$
  mod_gzip_item_include mime ^text/.*
  mod_gzip_item_include mime ^application/x-javascript.*
  mod_gzip_item_exclude mime ^image/.*
  mod_gzip_item_exclude rspheader ^Content-Encoding:.*gzip.*
</IfModule>

# Block Bad Bots
# Block one or more IP address.
# Replace IP_ADDRESS_* with the IP you want to block
<Limit GET POST>
order allow,deny
deny from IP_ADDRESS_1
deny from IP_ADDRESS_2
allow from all
</Limit>


# Restrict All Access to wp-includes
# Block wp-includes folder and files
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^wp-admin/includes/ - [F,L]
RewriteRule !^wp-includes/ - [S=3]
RewriteRule ^wp-includes/[^/]+\.php$ - [F,L]
RewriteRule ^wp-includes/js/tinymce/langs/.+\.php - [F,L]
RewriteRule ^wp-includes/theme-compat/ - [F,L]
</IfModule>

# Allow only Selected IP Addresses to Access wp-admin
# Limit logins and admin by IP
<Limit GET POST PUT>
order deny,allow
deny from all
allow from 302.143.54.102
allow from IP_ADDRESS_2
</Limit>


# Protect wp-config.php and .htaccess from everyone
# Deny access to wp-config.php file
<files wp-config.php>
order allow,deny
deny from all
</files>
# Deny access to all .htaccess files
<files ~ "^.*\.([Hh][Tt][Aa])">
order allow,deny
deny from all
satisfy all
</files>


# Redirect to a Maintenance page
# Redirect all traffic to maintenance.html file
RewriteEngine on
RewriteCond %{REQUEST_URI} !/maintenance.html$
RewriteCond %{REMOTE_ADDR} !^123\.123\.123\.123
RewriteRule $ /maintenance.html [R=302,L] 

# Custom Error Pages
# Custom error page for error 403, 404 and 500
ErrorDocument 404 /error.html
ErrorDocument 403 /error.html
ErrorDocument 500 /error.html



# Hide extension like .html or .php from the URL path show only file name in normal HTML or PHP sites
<IfModule mod_rewrite.c>
    RewriteEngine On
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteRule ^([^\.]+)$ $1.php [NC,L]
</IfModule>


# Protect .htaccess From Unauthorized Access
<files ~ "^.*\.([Hh][Tt][Aa])">
order allow,deny
deny from all
satisfy all
</files>

# Increase File Upload Size
php_value upload_max_filesize 64M
php_value post_max_size 64M
php_value max_execution_time 300
php_value max_input_time 300

# Blocking Author Scans in WordPress

RewriteEngine On
RewriteBase /
RewriteCond %{QUERY_STRING} (author=\d+) [NC]
RewriteRule .* - [F]


# Password Protect your Applection Admin Login DIR
AuthName "Admins Only"
AuthUserFile /home/yourdirectory/.htpasswds/public_html/wp-admin/passwd
AuthGroupFile /dev/null
AuthType basic
require user putyourusernamehere
<Files admin-ajax.php>
Order allow,deny
Allow from all
Satisfy any 
</Files>

Just a FYI, you can never actually block my htshells project with a .htaccess file :) You really should disable .htaccess globally and use apache config instead.

Can we use it for any site without change?

You can use as per your need

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