Add your Dynamic DNS Name to Apache HTACCESS files

stardothosting.com initially created this script for just 1 dynamic IP and can be seen at this URL:

https://www.stackstar.com/blog/2012/05/add-your-dynamic-ips-to-apache-htaccess-files/

I modified their script to meet my needs:

• Multiple dynamic IPs
• Allow "allow from xxx.xxx.xxx.xxx" to be inserted into a pre-existing htaccess configuration

To start, you MUST first manually enter the <Files wp-login.php> section into your htaccess file BEFORE first use. If your htaccess file already has this section, then lines 1 & 2 MUST start the section. Lines 3 & 4 can dynamically move down if you have your own wp-login.php configurations that you need to maintain; in other words, add your configuration data between lines 2 & 3. Note: Once you enter this section and save the htaccess file, you WILL NOT BE ABLE to access your Wordpress site until your cron job is first run.

The cron entry setup is just like stardothosting.com's setup:

You may create multiple cron jobs for multiple dynamic DNS names:

And so forth...

And now the script:

#!/bin/bash
# Dynamic IP .htaccess file generator
# Initially written by Star Dot Hosting
# https://www.stackstar.com/blog/2012/05/add-your-dynamic-ips-to-apache-htaccess-files/
#
# Added support for multiple Dynamic domains
# Added support to insert the domain into an already existing htaccess file
# by Rob Stokes
# www.assuredsolutions.com
#
# The htaccess file MUST contain this "Files wp-login.php" section upon first use.
# If the sections exists exactly as printed, then insert these lines manually withOUT the pound signs in your htaccess file.
# Once you enter this section, you WILL NOT BE ABLE to access your Wordpress site until your cron job first runs.
#<Files wp-login.php>
#order deny,allow
#deny from all
#</Files>

dynDomain="$1"
htaccessLoc="$2"

dirname="${htaccessLoc%/*}" # get directory/path name
echo "Directory of htaccess file: $dirname"
 
dyn_IP=$(dig +short $dynDomain) # get IP number of $dynDomain
echo "dyn_IP: $dyn_IP"

# verify dyn_IP resembles an IP
if ! echo -n $dyn_IP | grep -Eq "[0-9.]+"; then
    exit 1
fi

# create IP-Hold file name
# https://stackoverflow.com/questions/9697268/how-to-use-regex-to-reverse-text-in-bash-script
domain_r=`echo $dynDomain | awk '{n=split($0,A,".");S=A[n];{for(i=n-1;i>0;i--)S=S"."A[i]}}END{print S}'`
domain_r="$domain_r.txt"
echo "IP-Hold file name: $domain_r"
dyn_file_contents="#allow from $dynDomain=$dyn_IP\nallow from $dyn_IP"

echo "Checking for $dynDomain in $htaccessLoc"
if ! cat $htaccessLoc | grep -q "#allow from $dynDomain"; then

		echo "$dynDomain is NOT in $htaccessLoc"
		# insert $dynDomain in <Files wp-login.php>
		search_s="<Files wp-login.php>\norder deny,allow\n"
		replace_s="<Files wp-login.php>\norder deny,allow\n$dyn_file_contents\n"
		perl -i -p0e "s/$search_s/$replace_s/s" $htaccessLoc

		# save a the new domain name and IP to $domain_r for future reference
		printf "$dyn_file_contents" | tee $dirname/$domain_r
		echo ""

fi

echo "Checking for $dyn_IP in $htaccessLoc"
if ! cat $htaccessLoc | grep -q "$dyn_IP"; then

		echo "$dyn_IP is NOT in $htaccessLoc"
        # grab the old IP
        old_file_contents=`cat $dirname/$domain_r`
        echo "old_file_contents: $old_file_contents"
  		
        # output .htaccess file
		perl -i -p0e "s/$old_file_contents/$dyn_file_contents/s" $htaccessLoc
 
        # save the new ip to remove next time it changes, overwriting previous old IP
		printf "$dyn_file_contents" | tee $dirname/$domain_r
		echo ""

fi