Network Troubleshooting Basics

Network Troubleshooting Basics

• Network troubleshooting involves two main approaches: pre-emptive planning and reactive troubleshooting.
• Pre-emptive troubleshooting focuses on preventing problems through careful planning and management of the network.
• Reactive troubleshooting addresses existing network issues.

Preventing Problems

• Physical Environment: Factors like temperature, air quality, and magnetism can affect network performance.
• Electrical Environment: Crosstalk (noise between wires), EMI (electromagnetic interference), RFI (radio frequency interference), and static (ESD - electrostatic discharge) are potential problems.
  • Crosstalk can be mitigated by using Shielded Twisted Pair (STP) cables instead of Unshielded Twisted Pair (UTP).
  • EMI and RFI can be reduced by avoiding placing cables near potential sources and using shielding.
  • Properly grounding equipment and using antistatic bags can help prevent ESD.
• Software Threats: Viruses, worms, and Trojan horses are malicious programs that can damage or disrupt a network.

Viruses, Worms, and Trojans

• Definition of a Virus: A self-replicating program that inserts copies of itself into other executable code or documents.
• What Viruses Do: Damage files, slow systems, display messages, and gain control.
• Types of Viruses:
  • Macro viruses: Common, mostly affecting Microsoft Office documents.
  • Executable viruses: Second most common, compiled into executable files.
  • Backdoor programs: Allow remote control of an infected computer.
  • Boot sector viruses: Rare, reside in the boot sector instead of files.
  • Macintosh viruses: Often target Macro vulnerabilities; executables and backdoors don't typically work.
  • Hoaxes: Warnings about non-existent viruses.
• Methods of Spreading:
  • Parasites: Embed themselves into programs or data files and spread when the infected file is opened.
  • Worms: Attempt to spread to other computers independently. Recent worms often use email attachments.
  • Trojan Horses: Disguise themselves as useful programs, modifying system files while running.
  • Booting: Boot sector viruses copy themselves to the boot sector of a disk and load into memory when the computer boots, enabling the virus to infect other disks.

Anti-Virus Software

• Anti-virus software automatically loads at startup and monitors all interactions with files, searching for hexadecimal patterns defined in Virus Definition Files.
• Virus Definition Files need regular updates to detect new viruses.

Network Management and Planning

• Preventative measures are essential, and combining network management with troubleshooting leads to a more effective plan.
• Include things like cable diagrams, network capacity, protocols, standards, documentation on device configuration, software, and important files.

Backing Up Network Data

• Comprehensive backup programs are crucial to prevent data loss.
• Key components of a backup program include:
  • Determining what data to back up and how frequently.
  • Specifying the backup type and schedule.
  • Identifying who is responsible for backups.
  • Regularly testing the backup system and verifying logs are complete.
  • Defining where backups are stored and if offsite options exist.

Setting Security Policies

• Security policies are an essential component of a network plan and include both data and hardware security.
• Critical aspects of security policies, specifically for user accounts, include:
  • Password change frequency.
  • Password reuse restrictions.
  • Password character restrictions and policy standards.
  • Procedures for defining and documenting exceptions.
• Access guidelines should be in place to grant access to those who require it and establish minimum levels.