I am trying to allow some particular domain to access my site via iframe
Header set X-Frame-Options ALLOW-FROM https://www.that-site.com
I
I found that if the application within the httpd server has a rule like "if the X-Frame-Options header exists and has a value, leave it alone; otherwise add the header X-Frame-Options: SAMEORIGIN" then an httpd.conf mod_headers rule like "Header always unset X-Frame-Options" would not suffice. The SAMEORIGIN value would always reach the client.
To remedy this, I add two, not one, mod_headers rules (in the outermost httpd.conf file):
Header set X-Frame-Options ALLOW-FROM http://to.be.deleted.com early
Header unset X-Frame-Options
The first rule tells any internal request handler that some other agent has taken responsibility for clickjack prevention and it can skip its attempt to save the world. It runs with "early" processing. The second rule strips off the entirely unwanted X-Frame-Options header. It runs with "late" processing.
I also add the appropriate Content-Security-Policy headers so that the world remains protected yet multi-sourced Javascript from trusted sites still gets to run.
This worked for me on all browsers:
What did it for me was the following, I've added the following directive in both the http <VirtualHost *:80> and https <VirtualHost *:443> virtual host blocks:
ServerName your-app.com
ServerAlias www.your-app.com
Header always unset X-Frame-Options
Header set X-Frame-Options "SAMEORIGIN"
The reasoning behind this? Well by default if set, the server does not reset the X-Frame-Options header so we need to first always remove the default value, in my case it was DENY, and then with the next rule we set it to the desired value, in my case SAMEORIGIN. Of course you can use the Header set X-Frame-Options ALLOW-FROM ... rule as well.
See X-Frame-Options header on error response
You can simply add following line to .htaccess
Header always unset X-Frame-Options
.htaccess, httpd.conf or VirtualHost sectionHeader set X-Frame-Options SAMEORIGIN this is the best optionAllow from URI is not supported by all browsers. Reference: X-Frame-Options on MDN