Ok here is something that can be very good to do:
Add this under your "header" section at the top of your index page:
<base href="http://www.mydomain.com" target="_top"/>
(Complements of BillThor whos is a very senior member on this site)
By doing this, the person who has his domain pointed to yours .. once someone gets there and clicks on a link, it will redirect them to use your links so they only can steal the home page link and nothing else).
Unfortunately there is no way to stop these kind of people. but all you can do is do a redirect back to your links from his domain.
Another permanent fix to this pesky problem.
It depends on what server program you are using, but for, apache2
has its virtual host settings in the '/etc/apache2/site-enabled'
directory. Basically, it has a default virtual hosts ('000-default')
and this is set for the mydomain.com site for now. Thus,
here is my approach.
Copy the current 000-default to 010-somename. (Please be
careful, 000-default is usually symbolic link file so you have to copy
it from ../site-available/default.)
Set the virtual host setting in 010-somename. Add these two
lines below the first line
Make 000-default points to other directory (elsewhere). In
'000-default' file, change 'DocumentRoot /var/www' to point other
location like 'DocumentRoot /var/www-test'. The directory
/var/www-test don't need to exists, If it is not exists, the
connections using other domain name will get error.
Restart apache2 : "sudo /etc/init.d/apache2 restart"
I hope this is helpful.