4.6. Reflection Checkpoint

Before moving to Phase 5, confirm you can answer these from understanding:

Permissions and SELinux:

• What is the octal permission value for rw-r-----?
• A file has ACLs configured. How can you tell from ls -l output?
• SELinux shows a denial in the audit log. What is the difference between fixing it with chcon vs. semanage fcontext + restorecon?
• A process is in SELinux Permissive mode. Is it protected? Explain.

Firewalls:

• What is the difference between firewall-cmd --add-service=http and firewall-cmd --permanent --add-service=http?
• What must be enabled for a Linux server to route packets between two interfaces?
• iptables rules are lost after reboot. What command saves them, and what service restores them?

Cryptography:

• What is the difference between encryption and hashing? Give one tool for each.
• You have a LUKS2-encrypted disk to decommission. Why is cryptographic destruction faster AND more secure than dd if=/dev/urandom?
• A server's TLS certificate is self-signed. Does traffic get encrypted? Is the connection authenticated? Explain both.

Hardening and Compliance:

• What two sshd_config settings are most critical for basic SSH hardening?
• AIDE reports a hash change on /usr/bin/sudo. You haven't updated any packages. What are the two most significant possible explanations?
• What is the difference between OpenSCAP and CIS Benchmarks?