Linux Security refers to the set of measures taken to protect a Linux-based system from unauthorized access, unauthorized modifications, and other security threats. It includes a combination of technical solutions, such as encryption, firewalls, access control, and intrusion detection, as well as operational practices, such as user authentication, software updates, and backups.
An example of Linux security is the use of a firewall to block unauthorized access to network ports on a Linux server. Firewalls allow only specific traffic to enter a network based on predefined policies, preventing undue access and potential security breaches. Another example of Linux security is the use of access control measures, such as password policies and user permissions, to control who can access certain files and directories on the system. These measures help prevent unauthorized users from accessing sensitive data or services residing on the system.
User authentication - Linux has robust user authentication mechanisms that ensure only authorized users can access the system.
File permissions - Linux uses file permissions and access control lists (ACLs) to ensure that only authorized users and processes can access files and directories.
Firewalls - Linux supports a range of firewalls and network security tools that help to protect against network attacks and intrusions.
Encryption - Linux systems support a range of encryption technologies that can be used to protect sensitive data, including SSH, SSL/TLS, and disk encryption.
System updates - Regular software updates help to protect Linux systems against security vulnerabilities and exploits.
Auditing - Linux includes tools that allow system administrators to monitor, log, and analyze system activity and security events.
Secure boot - Secure boot ensures that the system only boots from trusted sources and that the root file system is protected from unauthorized changes.
Network security - Linux includes built-in support for virtual private networks (VPNs), secure remote access (SSH), and other network security technologies.
Malware detection and removal - Linux includes a range of tools for detecting and removing malware, including antivirus software, rootkit scanners, and intrusion detection systems.
Application security - Application-level security measures, such as sandboxing, mandatory access control (MAC), and stack smashing protection, help to prevent applications from being exploited by attackers.
What is the default file permission for a newly created file in Linux and how can you modify it?
Answer: The default file permission for a newly created file in Linux is 666 (rw-rw-rw-). You can modify it by using the chmod command and specifying the appropriate permission settings, such as 755 (rwxr-xr-x) or 644 (rw-r–r–).
How can you configure a firewall in Linux to block incoming traffic from a specific IP address?
Answer: You can use the iptables command to configure a firewall in Linux. To block incoming traffic from a specific IP address, you can use the following command: iptables -A INPUT -s -j DROP
What is the purpose of SELinux in Linux and how can you enable it?
Answer: SELinux is a security mechanism in Linux that provides fine-grained access control and mandatory access control (MAC) over files, processes, and other system resources. You can enable SELinux by modifying the /etc/selinux/config file and setting the SELINUX parameter to enforcing or permissive mode.
How can you encrypt a file or directory in Linux and what is the recommended algorithm to use?
Answer: You can encrypt a file or directory in Linux using the GnuPG (GPG) tool, which supports symmetric-key and public-key encryption. The recommended algorithm to use for symmetric-key encryption is AES-256, which provides strong encryption and is widely used in security applications.
How can you configure Linux to rotate log files automatically and prevent disk space from being filled?
Answer: You can configure Linux to rotate log files automatically by using the logrotate utility, which can be configured to rotate log files based on size, age, or other criteria. To prevent disk space from being filled, you can set the maxsize parameter in the logrotate configuration file and specify the maximum size that a log file can grow before it is rotated.