Linux consists of the user space and kernel space. Which of the following functions are included in the kernel space? (Select All that Apply)

The Linux kernel space is responsible for low-level system tasks and direct hardware management. This includes: (A) NIC drivers, which are kernel modules that control the network hardware to send and receive data frames; (B) Data encapsulation, performed by the kernel's integrated TCP/IP stack which adds necessary headers (e.g., TCP, IP, Ethernet) to application data; and (C) initiating bit stream transmission by passing finalized frames to the NIC hardware, which then handles the physical layer signaling.

D. Data encryption can occur in both kernel space (e.g., IPsec for VPNs) and user space (e.g., TLS/SSL libraries like OpenSSL used by web browsers and servers), so it is not exclusively a kernel-space function.

1. Bovet, D. P., & Cesati, M. (2005). Understanding the Linux Kernel, 3rd Edition. O'Reilly Media. Chapter 1, "Introduction," describes the separation between kernel space and user space, placing device drivers and the networking stack firmly within the kernel.

2. Tanenbaum, A. S., & Bos, H. (2014). Modern Operating Systems, 4th Edition. Pearson. Chapter 10, "Computer Security," explains that while some encryption like IPsec is in the kernel, application-level security protocols like SSL/TLS operate in user space.

3. Stanford University, CS 140: Operating Systems Course Notes, "Networking". The courseware explains how the networking stack (protocol encapsulation) and device drivers are implemented within the OS kernel to manage network I/O.