.htaccess - Maintenance mode with whitelisted IP's

.htaccess

# Rewrite url for maintenance mode
<IfModule mod_rewrite.c>
	RewriteEngine On
	RewriteCond %{REMOTE_ADDR} !^123\.456\.78\.90
	RewriteCond %{DOCUMENT_ROOT}/maintenance.html -f
	RewriteCond %{DOCUMENT_ROOT}/maintenance.true -f
	RewriteCond %{SCRIPT_FILENAME} !maintenance.html
	RewriteRule ^.*$ /maintenance.html [R=503,L]
	ErrorDocument 503 /maintenance.html
</IfModule>

# Set headers
<IfModule mod_headers.c>
	# 3600 = 60 minutes
	# 86400 = 1 day
	Header Set Cache-Control "max-age=0, no-store"
	Header always set Retry-After "86400"
</IfModule>

If the maintenance.true file exists, all traffic will be redirected. I rename the file to maintenance.false for easy switching.