The Basics of Network Troubleshooting PDF

# The Basics of Network Troubleshooting ## Chapter No.12 ## Preventing Problem * Physical environment * Electrical environment * Viruses, Worm, Trojan Horses ## Problem in Physical Environment * Temperature * Air Quality * Magnetism ## Electrical Problems * Crosstalk * UTP * So...

# The Basics of Network Troubleshooting ## Chapter No.12 ## Preventing Problem * Physical environment * Electrical environment * Viruses, Worm, Trojan Horses ## Problem in Physical Environment * Temperature * Air Quality * Magnetism ## Electrical Problems * Crosstalk * UTP * Solution STP * Noise * EMI * RFI * Solution * Properly ground equipment * Avoid placing cable close to possible EMI and RFI sources * Use shielding in cables whenever possible ## Electrical Problems * Static * ESD (Electrostatic discharge) * Solution * Always ground yourself and equipment * Never let anyone touch you while you are working * Never directly touch electrical leads of components * Always use antistatic bags * Transient * Transient also commonly called spikes, is high voltage burst of current. * Solution * Put the computer on its own circuit with a separate breaker. * Ensure that a computer is properly grounded ## Definition * A virus is a self-replicating program that spreads by inserting copies of itself into other executable code or documents made by crackers. ## What do viruses do? * Can damage files * Can slow system * Can show messages * Can take control ## Types of Viruses * Macro Viruses * Executable Viruses * Backdoor Programs * Boot Sector Viruses * Macintosh Viruses * Hoaxes ## Macro Viruses * Most common type of virus on campus * Affect Microsoft Office documents * Written in Visual Basic for Applications * Generally harmless with a few destructive variants ## Executable Viruses * Second most common type of virus on campus * Written in programming languages and compiled into executable files * Generally more destructive ## Backdoor Programs * Sub-type of executable viruses * Allow anyone on the internet to remotely control the infected computer * Send and receive files * View the screen * Start programs * Monitor all keystrokes ## Boot Sector Viruses * Rare viruses * Similar to executable except the reside in the boot sector instead of as a file * Generally very destructive ## Macintosh Viruses * Most virus code will not affect Macintosh computers * Macro viruses target "C:\" * Executables can not execute * Backdoors can not execute * Boot Sector Viruses can not infect HFS * Macintosh computers can be carriers of Macro Viruses ## Hoaxes * Warnings about viruses that do not exist * Characteristics * Claims the virus causes large amounts of damage but lack specifics on how it works * Claims unrealistic person (Bill Gates) or company (AOL) started the warning * Encourage you to pass it on to everyone you know ## Methods Viruses Use to Spread * Parasites * Worms * Trojan Horses * Booting ## Parasites * Imbed themselves into a program or data file * Spread to other files when the infected file is opened * Only spread to other computers when the files are shared ## Worms * Attempt to spread themselves to other computers instead of only infecting files on the local computer * Recent worms automatically send e-mail attachments containing copies of the virus ## Trojan Horses * Disguise themselves as usefull programs * Greetings cards * Games * Screen Savers * Modify system files while the 'usefull' program executes ## Booting * Boot sector viruses copy themselves to the boot sector of a disk * When the disk is used to boot a computer, the code is loaded into memory * The code resident in memory can be used to deliver the payload and to infect other disks ## How Anti-Virus Software Works * Automatically loaded at start-up time * Monitors all interaction with files * Looks for hexadecimal patterns within files. These patterns are defined by Virus Definition Files * Virus Definition Files must be updated regularly to ensure new viruses can be detected ## Preventing Problems with Network Management and Planning * Two ways to solve networking problems * Prevent them through planning and management * Called pre-emptive troubleshooting or trouble avoidance * Repair and control damage that already exists * Called troubleshooting ## Preventing Problems with Network Management and Planning (continued) * Combine network management and troubleshooting to form overall network plan * Include cable diagrams, cable layers, network capacity information, protocols and network standards, documentation on computer and network device configuration, software, and important files * Establish network policies and procedures * Include back-up methods, security, hardware and software standards, upgrade guidelines, and documentation ## Backing Up Network Data * To prevent data loss, develop comprehensive back-up program, including: * What data should be backed up and how often? * What type of backup will be performed, how often, and what time? * Who is responsible for performing backups? * Is backup system being tested regularly? * Is backup log complete? * Where is backed-up data stored (on-site and off-site)? * Table 13-1 shows several back-up methods ## Backup Methods | Method | Description | |--------------|----------------------------------------------------------------------------------------------------------------------------------------------------------| | Full backup | Backs up all selected files and marks them as backed up, whether or not they have changed since they were last backed up | | Copy | Backs up all selected files without marking them as backed up | | Incremental | Backs up all selected files and marks them as backed up, but only if they have changed since they were last backed up | | Daily copy | Backs up only files modified that day and does not mark them as backed up | | Differential | Backs up selected files only if they have changed since they were last backed up but does not mark them as backed up | ## Setting Security Policies * Security policies are part of network plan * Include both data and hardware security * Primary data security is username and passwords for all accounts, including: * How often users change passwords * Whether users can reuse same passwords * What character restrictions passwords have * Whether passwords have single or multiple sets of standards * How exceptions are defined and documented ## Setting Security Policies (continued) * Establish guidelines for resource access * Grant access only to users who require it * Grant minimum levels of access * Set special security requirements for dial-in accounts * Keep to a minimum the number of users who perform network administration tasks Guide to Networking Essentials, Fourth Edition 21-26