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📝 Firewalling to Protect Systems and Networks

📖 From Operating System • 15. Security • 14 questions available

Practice MCQs for Firewalling to Protect Systems and Networks. Test your knowledge with carefully crafted questions across easy, medium, and hard difficulty levels.

🔄 Last updated: 2026-07-27

3
Easy Questions
6
Medium Questions
5
Hard Questions

📝 Sample Questions

Q1. A Linux administrator wants to enable the NX (non‑executable) feature for all processes. Which command sequence will correctly activate it on a typical modern distribution?

🔹 A. echo \1\ > /proc/sys/kernel/randomize_va_space; sysctl -w vm.mmap_min_addr=65536
🔹 B. sysctl -w vm.nr_hugepages=0; echo \0\ > /proc/sys/kernel/execve_blacklist
🔹 C. sysctl -w vm.mmap_min_addr=0; echo \1\ > /proc/sys/kernel/exec_prot
🔹 D. sysctl -w kernel.exec-shield=1; echo \1\ > /proc/sys/kernel/exec_prot

💡 Difficulty: easy | ✅ Correct: B

Q2. A legacy x86 application suffers a stack‑based buffer overflow. The system has NX disabled. Which outcome is most likely when the overwritten return address points to the injected shellcode on the stack?

🔹 A. The injected code will execute, giving the attacker control
🔹 B. The CPU will raise a page‑fault and abort the program
🔹 C. The operating system will automatically quarantine the process
🔹 D. The overflow will be silently ignored and the program will continue normally

💡 Difficulty: medium | ✅ Correct: A

Q3. How does marking a memory page as non‑executable mitigate the risk of a buffer‑overflow attack?

🔹 A. It forces the attacker to use return‑oriented programming instead of shellcode
🔹 B. It prevents the CPU from fetching instructions from that page, causing a fault if overflowed code tries to run
🔹 C. It encrypts the page so the attacker cannot read its contents
🔹 D. It moves the page to a separate address space inaccessible to the process

💡 Difficulty: hard | ✅ Correct: A

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🔗 Related Topics

📝 The Security Problem in Operating System📝 Program Threats in Operating System📝 Trojan horse📝 Trap door📝 Logic bomb
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