To temporarily save iptables rules, one would use the command iptables-save > **rules.txt**. This command saves the current firewall rules to a file called "rules.txt" for later use or backup.

Kali Linux is a Linux distribution that focuses primarily on security and is widely used for penetration testing and ethical hacking. It comes pre-installed with a variety of security tools and is maintained by Offensive Security.

AppArmor policies are commonly defined using profiles. These profiles specify the access controls for individual applications or processes, allowing you to confine their behavior and enhance system security.

The "du" (disk usage) command is used to display the disk usage of files and directories in Linux. It provides information about the space consumed by each file or directory, helping you manage disk space effectively.

The correct answer is "top." The top command is a real-time system monitoring tool in Linux that provides information about system processes, CPU usage, memory usage, and more. It allows users to monitor and manage running processes interactively.

To find all occurrences of the word "error" in a directory with log files, you would primarily use the grep command. grep is a powerful tool for searching text and regular expressions in files and can be used to quickly locate specific content, like error messages, within files.

The correct command to send ICMP echo requests to test network connectivity is 'ping.' When you run 'ping' followed by an IP address or hostname, it sends ICMP echo requests to that address and waits for responses, allowing you to determine if the network connection is working.

In Bash scripting, the '$' symbol is used to execute a command. When you prefix a command with '$', it's interpreted as a variable and executed. For example, $ ls would execute the 'ls' command.

In Debian and its derivatives, the primary tool used for package management is APT (Advanced Package Tool). APT is a package management system that allows users to install, upgrade, and remove software packages on Debian-based systems.

The nslookup command can be used to query DNS (Domain Name System) records, including MX (Mail Exchange), NS (Name Server), and SOA (Start of Authority) records. It's a valuable tool for DNS troubleshooting and network diagnostics.