10. Missing updates and dependencies: Missing critical updates and dependencies can lead to security vulnerabilities and instability.
11. Downstream failures due to updates: Updates to one component or service can cause downstream issues with other components or services.
12. Inappropriate application-level permissions:
If applications are given inappropriate permissions, it can lead to security vulnerabilities or system instability.
13. Improper CPU affinity and priority: Assigning the wrong CPU affinity or priority to a process or service can cause performance issues or system instability.
OS and software tools and techniques
Here is a detailed explanation of OS and software tools and techniques:
a. Patching: Patching is the process of updating software or operating systems to fix bugs, improve performance, and address security vulnerabilities. Patches can be upgrades or downgrades, depending on the situation.
Upgrades: Upgrades involve updating to a newer version of the software or OS, which may include additional features and bug fixes. They may require a reboot of the system.
Downgrades: Downgrades involve rolling back to a previous version of the software or OS. This may be necessary if a new version causes problems or conflicts with other software.
b. Package management: Package management is the process of installing, updating, and removing software packages. It includes tools for downloading and installing packages, checking for updates, and resolving dependencies.
c. Recovery: Recovery involves restoring a system to a previous state or configuration. This may be necessary if the system is not booting or if critical files have become corrupted. Recovery options include:
Boot options: These are settings that control the startup of the OS. They may include options to boot into safe mode or single-user mode.
Safe mode: Safe mode is a minimal boot configuration that disables nonessential drivers and services. It can be used to troubleshoot startup problems or remove malware.
Single user mode: Single user mode is a command-line mode that provides access to the system as the root user. It can be used to troubleshoot and repair system files.
Reload OS: This involves reinstalling the operating system from scratch. It is a last resort option that should only be used if all other recovery options have failed.
Snapshots: Snapshots are copies of the system state that can be used to restore the system to a previous state. They are typically created using backup software.
d. Proper privilege escalations: Privilege escalation is the process of gaining higher-level access to a system or application. It can be necessary to perform certain tasks or to troubleshoot problems. Common tools for privilege escalation include:
runas/Run As: This is a command-line tool that allows a user to run a program with different credentials, such as an administrator account.
sudo: Sudo is a Unix/Linux command that allows a user to execute a command as another user, such as the root user.
su: Su is a Unix/Linux command that allows a user to switch to another user account, such as the root user.
OS tools and techniques
a) Scheduled reboots: Scheduled reboots are a process of restarting a computer system automatically at a specific time, date, or day of the week. This is usually done to apply updates or changes that require a system restart. Scheduled reboots ensure that the system remains stable, up-to-date, and secure. They can be configured through various methods, including the task scheduler in Windows or cron jobs in Unix-based systems.
b) Software firewalls: Software firewalls are a type of firewall that is installed on the host system and operates at the software level. They are used to control the flow of network traffic to and from the host system. Some common tools used for software firewalls include Windows Firewall for Windows systems and iptables for Linux-based systems. Adding or removing ports and defining zones are common techniques used for configuring software firewalls.
c) Clocks: Clocks are used to synchronize the system time and maintain accurate time on the computer. Network time protocol (NTP) is a protocol used for synchronizing clocks on computer systems within a network. It enables a system to synchronize its clock with a time server, which provides the most accurate time. System time refers to the time kept by the computer's internal clock.
d) Services and processes: Services and processes are essential components of an operating system. Services are programs that run in the background and provide functionality to the system, such as network connectivity or printing. Processes are instances of a program that are currently running on the system. Starting, stopping, and identifying the status of services and processes are common techniques used for managing them. Dependencies refer to the relationships between different services and processes, and understanding them is critical for troubleshooting and system maintenance.
e) Configuration management: Configuration management refers to the process of managing system configuration settings and ensuring consistency across all systems in an organization. Tools such as System Center Configuration Manager (SCCM), Puppet, Chef, and Ansible are used for automating configuration management tasks. Group Policy Object (GPO) is a feature in Windows that allows administrators to manage user and computer settings across an organization.
f) Hardware compatibility list (HCL): A hardware compatibility list (HCL) is a list of hardware components that are compatible with a particular operating system or software application. It helps administrators and users identify which hardware components are supported and can be used with the system. The HCL is usually maintained by the hardware or software vendor and is regularly updated to include new components and remove outdated or unsupported ones.
