What is NoEx and How Does It Work in Linux?

NoEx (short for "No Execution") is a feature in the Linux kernel that allows the operating system to prevent the execution of specific programs or commands.

When a program or command is marked as "noexec", it means that the kernel will not allow the program to execute any code, even if it has permission to do so. This can be useful in situations where you want to prevent a program from doing something malicious, but you don't want to completely block it.

For example, if a user tries to run a program that is known to be malicious, the kernel might block the program from running altogether. But if the program is marked as noexec, the kernel will allow the program to run, but it will not be able to execute any code. This can help to prevent the program from causing harm, while still allowing the user to see what the program is doing.

NoEx is typically used in security contexts, such as in jails or sandboxes, where you want to limit the capabilities of a program without completely blocking it.