Networking Concepts Lesson 13 - Troubleshooting - Eric Vanderburg

1. Chapter 13
Troubleshooting
Networking Concepts – Eric Vanderburg ©2005

2. Proactive measures
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Policy
Naming conventions
 Internet use policy
 Security policy
 Privacy policy
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Networking Concepts – Eric Vanderburg ©2005

3. Proactive Measures
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Planning
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Network diagrams
Documentation
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Address list
Cable map
Contact list – who to contact when an event happens
Equipment list
Network history – upgrade history
Network map
Hardware configuration – routers, switches…
Server configuration
Licensing
Users
Software should be used to speed the process up
Networking Concepts – Eric Vanderburg ©2005

4. Network Inventory
Networking Concepts – Eric Vanderburg ©2005

5. Machine Screen from Inventory
Networking Concepts – Eric Vanderburg ©2005

6. Backup
Determine the files to backup
 Make a schedule
 Specify backup personnel
 Test the backups
 Record and check backup logs
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Networking Concepts – Eric Vanderburg ©2005

7. Upgrades
Establish guidelines for upgrades
 Give users advance notice of changes
 Backup prior to each upgrade
 Upgrade during off time
 Test upgrades in a lab or with a pilot
group to resolve problems early
 Have plan to undo upgrade installation if
necessary
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Networking Concepts – Eric Vanderburg ©2005

8. Logging
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Auditing
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Enable auditing on all servers
Audit administrative actions
Audit critical files and folders
Audit access to certain rights
Filter and review logs regularly
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Event Viewer
Programs have their own logs too (.log, .txt)
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Windows setup logs: setuterr.log, setupapi.log,
setuplog.txt
Networking Concepts – Eric Vanderburg ©2005

9. Utilities
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Snort IDS
Ethereal Protocol analyzer
Network Monitor
Port scanners
SNMP (Simple Network Management Protocol)
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MIB (Management Information Base) – place where each agent
stores its informaiton
Agents are installed on hosts – they report back to a SNMP
management program
Basic network configuration can take place through SNMP
RMON (Remote Monitoring)
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Agents (probes) can be hubs, switches, or routers also (not cheap)
Has 8 different MIB types
RMON1 works at layer 1 & 2
RMON2 works at layer 3 and above
Networking Concepts – Eric Vanderburg ©2005

10. Customer Relations Skills
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Users are customers, and the reason network
personnel have jobs
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Best source of information when something goes
wrong with network
Develop special relationships with adept users
Develop guidelines about user interaction
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Include how to question and respond to users,
handle irate users, and general user
communication etiquette
Networking Concepts – Eric Vanderburg ©2005

11. Troubleshooting structured approach
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Set a priority
Collect information about the problem
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When did it happen
What has changed since the time when it was
working properly
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List possible causes
Test each possible to find actual
Try at least one solution for each potential
cause
 Do only one test at a time
 Document the solution
Networking Concepts – Eric Vanderburg ©2005

12. Tools
DVM (Digital Voltmeter) – measures the
resistance of cables to find a cable break
 TDR (Time Domain Reflectometer) –
Determines a break in the cable and specifies
where. Can also measure cable length
 Cable testers – check for correct termination,
attenuation, measures frame counts, ect..
 Oscilloscope – measures signal voltage over
time. Checks for breaks, crimps, and
attenuation problems.
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Networking Concepts – Eric Vanderburg ©2005

13. Software Tools
Protocol Analyzer
 MSBA (Microsoft Baseline Security
Analyzer)
 Port Scanner
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Networking Concepts – Eric Vanderburg ©2005

14. Resources
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MS Technet
(www.microsoft.com/technet/default.mspx)
MS Knowledge base – look up error codes
here. (support.microsoft.com)
Novell Knowledge base (support.novell.com)
MSDN (Microsoft Developer’s Network)
Newsgroups
Forums
Periodicals
Networking Concepts – Eric Vanderburg ©2005

15. Troubleshooting
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Check physical first
Define scope – user, group, entire network
Given problem information, develop a list of possible bad
software or hardware
Run tests on a component or application
Put a suspect component in a situation where everything else
works.
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Example: NIC is suspect. Take it out and place it in a computer that
is working properly and see if the NIC works there.
Example: Application does not work. Install on another PC and
check
Check logs
Lookup error codes
Networking Concepts – Eric Vanderburg ©2005

16. Troubleshooting
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Install needed service packs and patches
 Types
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QFE (Quick Fix Engineering) patch – first fix to a
problem
Hotfix – a QFE that has been tested for errors and
is packaged with an installer
Cumulative patch – a group of hotfixes that pertain
to a specific platform or product
Service pack – a cumulative patch that undergoes
months of intensive testing.
Networking Concepts – Eric Vanderburg ©2005

17. Test
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Test lab or pilot program
 Test patches before applying them on the
network
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SUS (Software Update Services) – creates an
alternate windows update for network clients. MS
updates can be approved first before appearing on
the list.
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Must be Win2k (SP3) or Win2k3
SMS (Systems Mgmt Server) – SUS plus inventory,
application usage tracking, vulnerability checks,
Test upgrades & new software
Networking Concepts – Eric Vanderburg ©2005