To support both L2TP and IPsec in a VPN setup, you would likely consider using StrongSwan. StrongSwan is an open-source IPsec-based VPN solution that supports both L2TP and IPsec, providing secure and reliable VPN connectivity.

The primary distinction between top and htop is that top displays real-time data about system processes, whereas htop provides more interactivity and customization. htop allows users to sort and filter processes, view detailed information, and easily send signals to processes directly from the interface. While both tools show similar information, htop offers a more user-friendly and feature-rich experience for process monitoring.

The /proc/cpuinfo file in the /proc directory is used to gather information about the system's CPU. It provides details about the processor, including its model, speed, and features. This is a valuable resource for understanding the CPU's capabilities and characteristics.

To ensure that filenames with spaces are treated as single arguments in a script, you should modify the OIFS (Original Internal Field Separator) variable. This allows you to temporarily change the IFS value to a specific character (e.g., newline) and then restore it to its original value after processing the filenames. This ensures that spaces don't break the filenames into multiple arguments.

The 'top' command is a Linux utility that allows you to monitor and manage system CPU performance. It provides a real-time view of system processes, CPU usage, memory usage, and more. You can use it to identify resource-intensive processes and manage system performance.

virt-manager is a graphical tool for managing virtual machines in Linux. It provides a user-friendly interface to create, configure, and manage virtual machines using various virtualization technologies, including KVM and QEMU.

A kernel that can have modules loaded and unloaded at runtime is referred to as a "modular" kernel. In a modular kernel, certain functionality can be added or removed via loadable kernel modules, making it more flexible and efficient.

To trace the system calls made by an application on Linux, you would use the strace tool. It provides detailed information about the system calls, signals, and other interactions the application has with the operating system, which is valuable for debugging and analysis.

OpenVPN is considered highly secure and commonly used in Linux. It's an open-source VPN protocol that provides strong encryption and is widely trusted for creating secure network connections.

The "passwd" command in Linux allows you to enforce a user to change their password upon the next login. This is often used for security reasons, such as when a user's password has expired.