20 Linux Security Interview Questions and Answers

Linux is a popular operating system for servers and other devices that require a high level of security. When interviewing for a position that involves working with Linux, you can expect to be asked questions about your knowledge of Linux security. Answering these questions confidently can help you demonstrate your expertise and land the job. In this article, we review some of the most common Linux security questions and provide tips on how to answer them.

Linux Security Interview Questions and Answers

Here are 20 commonly asked Linux Security interview questions and answers to prepare you for your interview:

1. What are the most common security threats in a Linux server environment?

The most common security threats in a Linux server environment include viruses, worms, and Trojan horses. These can all enter the system through malicious code that is injected into legitimate programs or files. Once inside, these programs can wreak havoc on the system, delete files, or even steal sensitive information. Other common threats include denial of service attacks and SQL injection attacks.

2. Can you explain what buffer overflow is? How can it be exploited by attackers to compromise system security?

A buffer overflow is a type of security vulnerability that can occur when too much data is written to a memory buffer. This can cause the program to crash or, in some cases, allow malicious code to be executed. Buffer overflows are often exploited by attackers to gain access to sensitive information or to take control of a system.

3. What’s the difference between a DoS attack and a DDoS attack?

A DoS attack is an attack meant to take down a single system, while a DDoS attack is an attack meant to take down multiple systems by flooding them with traffic.

4. Can you give me some examples of vulnerability scanners?

Some popular vulnerability scanners include Nessus, OpenVAS, and QualysGuard.

5. What steps should you take to protect your data from hackers?

There are a few key steps you can take to help protect your data from hackers. First, make sure that your operating system and all software are up to date with the latest security patches. Second, use strong passwords and never reuse passwords across different accounts. Third, encrypt your data both in transit and at rest. Finally, use a reputable security suite to help protect your data and monitor for any suspicious activity.

6. What are some examples of good password policies?

A good password policy is one that requires strong passwords, changes them regularly, and does not reuse passwords. Additionally, a good password policy will have a process in place for resetting passwords if they are forgotten, and will not allow users to write down their passwords.

7. Can you name some types of malware that target Linux systems?

There are many types of malware that target Linux systems, but some of the most common include viruses, worms, and Trojans. These malicious programs can cause a lot of damage to a system, and can even be used to steal sensitive information.

8. What are the most popular software packages used for firewalls on Linux servers?

The most popular software packages used for firewalls on Linux servers are iptables and firewalld.

9. What do you understand about intrusion detection systems?

Intrusion detection systems are designed to detect and respond to unauthorized activity within a computer system or network. There are two main types of intrusion detection systems: network-based intrusion detection systems and host-based intrusion detection systems. Network-based intrusion detection systems monitor network traffic for suspicious activity, while host-based intrusion detection systems monitor activity on individual computers.

10. What do you know about the TCP Wrapper tool?

The TCP Wrapper tool is a Linux security tool that can be used to restrict access to network services. By using the TCP Wrapper tool, you can specify which hosts are allowed to connect to which services. This can be used to help secure your network by only allowing trusted hosts to access sensitive services.

11. What are some ways to prevent unauthorized access to your Linux machine?

There are a few ways to help prevent unauthorized access to your Linux machine. One way is to use a strong password for your user account and make sure to use a different password for each account you have. Another way is to use a firewall to block incoming connections from untrusted sources. Finally, you can keep your software up to date to help close any security holes that may be present.

12. When using SSH, what is the significance of changing the default port number?

The significance of changing the default port number when using SSH is that it can help to improve security by making it more difficult for attackers to find and exploit vulnerabilities. By changing the port number, you are essentially hiding the SSH service from would-be attackers, which can make it more difficult for them to find and exploit any potential weaknesses.

13. What are the different types of file permissions available in Linux?

There are three types of file permissions in Linux: read, write, and execute. Read permissions allow a user to view the contents of a file; write permissions allow a user to edit or delete a file; and execute permissions allow a user to run a file as a program.

14. What do you understand about hardening the kernel?

Hardening the kernel is the process of making the kernel more resistant to attack. This can be done by disabling unneeded features, using security-focused patches, and increasing the overall security of the system.

15. What is IPtables? Why should you use it?

IPtables is a Linux kernel firewall that can be used to filter incoming and outgoing traffic. It is important to use IPtables to help secure your Linux server as it can help to block unwanted traffic and protect against attacks.

16. What are some of the most important things you can do to strengthen the security posture of your Linux system?

Some of the most important things you can do to strengthen the security posture of your Linux system include:

-Keeping your system up to date with the latest security patches
-Using strong passwords and enabling two-factor authentication
-Restricting access to sensitive files and directories
-Installing and configuring a firewall
-Monitoring your system for signs of intrusion

17. What is selinux? What does it do?

SELinux is a security enhancement to Linux which allows users more control over access to files and resources. It is especially useful in shared environments, such as servers, where different users may need different levels of access. SELinux can help to prevent accidental or malicious damage to files and systems by restricting access to only those users who need it.

18. What is SELinux policy? Where is it stored?

SELinux is a security policy that is stored in the file system. It is used to control access to files and resources on a Linux system.

19. What are some tools that can help you check if your Linux system has been compromised?

There are a few different tools that can help you check if your Linux system has been compromised. One is called chkrootkit, which checks for signs of a rootkit. Another is called rkhunter, which checks for known rootkits and other suspicious files. Finally, you can also check the system logs to see if there are any suspicious entries.

20. Name some advantages of using an open source operating system like Linux over more closed-source alternatives like Windows or Mac OS X.

One advantage of using an open source operating system like Linux is that the source code is freely available for anyone to view, modify, and redistribute. This means that there is a large community of developers who can contribute to improving the operating system, and it also makes it easier to find security vulnerabilities and patch them quickly. Additionally, open source operating systems are often more customizable than closed-source alternatives, so you can tailor the operating system to better fit your needs.