If you just need to execute individual commands through a URL, you can "install" a simple web shell: Use code with caution.
In a typical connection, you (the client) connect to the server. However, firewalls usually block incoming connections on non-standard ports. A flips this logic: You set up a "listener" on your machine. You upload or execute a PHP script on the target server. reverse shell php install
The server connects out to your machine. Since most firewalls allow outgoing traffic, the connection is established, granting you control. Prerequisites: Setting Up Your Listener If you just need to execute individual commands
If you have a way to execute command-line PHP but can't upload a full file, you can use a one-liner: the connection is established