You are working on a remote web server where you do not have have access to view the web server’s content on port 80. In my case I only had SSH shell access over port 22.
Use SSH’s port forwarding capability to serve the content locally on localhost.
sudo ssh -L 80:name_of_ip_of_webserver:80 username@name_or_ip_of_server_with_access_to_webserver
Then just provide the local root password and the password for username@name_or_ip_of_server_with_access_to_webserver. Make sure you stop Apache or other web server before doing this otherwise, this will fail because the port will not be able to bind to a port with an existing bound service. So you might need to do something like this.
sudo apache2ctl stop
Now all you need to do is point your favorite web browser to: http://127.0.0.1/