Chapter Twelve

1. 1 Chapter Twelve Troubleshooting Network Problems

2. 2 Troubleshooting Methodology Proceed w/ Logic and think of L1-L7 Do not discount the obvious! Steps to troubleshooting network problems Identify the symptoms Verify user competency Identify the scope of the problem Recreate the problem Verify the physical integrity of the network connection, starting at the affected nodes and moving outward toward the backbone

3. 3 Troubleshooting Methodology Steps to troubleshooting network problems (cont.) Verify the logical integrity of the network connection Consider recent changes to the network and how those changes might have caused a problem Implement a solution Test the solution

4. 4 Troubleshooting Methodology Verify user competency Ensure that human error is not the problem Be patient – do a step by step analysis Identify the scope of the problem How many users or network segments are affected? When did the problem begin? VERY important stage

5. 5 Practical Troubleshooting Staff involved in trouble shooting Help desk staffed with help analysts Organizations may group their help desk analysts into teams based on their expertise Most help desks have a help desk coordinator Most organizations have an operations manager, who supervises the help desk coordinator

6. 6 Examples of Problems Faced by Network Troubleshooters Unable to access the network One of the most common problems addresses is an inability to access the network Misbehaving printer Network printers cause as many problems as network workstations (though they are usually less critical than servers) Unable to connect to the Internet An inability to connect to the Internet can quickly hamper productivity and could perhaps affect the organization’s profitability

7. 7 Troubleshooting Follow-Up Document problems and solutions Call tracking system Software program for documenting problems Informally known as help desk software Building a knowledgebase

8. 8 Troubleshooting Follow-Up Important Fields for a Typical Problem Record Form The originator’s name, department, and phone number Information regarding whether the problem is software- or hardware-related If the problem is software-related, the package to which it pertains, or if hardware related, the devices or components to which it pertains Symptoms of the problem, including when it was first noticed

9. 9 Troubleshooting Follow-Up Important Fields for a Typical Problem Record Form (cont.) Name and telephone number of the network support contact Amount of time spent troubleshooting the problem Resolution of the problem Supported services list Lists every service and software package supported within an organization, plus the names of first- and second-level support contacts for those services or software packages

10. 10 Chapter Thirteen Ensuring Integrity and Availability

11. 11 Fault Tolerance Capacity for a system to continue performing despite an unexpected hardware or software malfunction Failure Deviation from a specified level of system performance for a given period of time Fault Involves the malfunction of one component of a system

12. 12 Fault Tolerance Fail-over Process of one component immediately assuming the duties of an identical component A sophisticated means for dynamically replicating data over several physical hard drives is known as hard disk redundancy, called RAID (for Redundant Array of Inexpensive Disks) Single point of failure Point on a network where, if a fault occurs, the transfer of data may break down without possibility of an automatic recovery

13. 13 Environment and Power Environment Analyze the physical environments in which your devices operate Power Whatever the cause, networks cannot tolerate power loss or less than optimal power

14. 14 Power Flaws Surge – momentary increase in voltage Line noise – EMF interference Brownout Also known as a sag Blackout – complete power loss

15. 15 Uninterruptible Power Supply (UPS) Battery-operated power source directly attached to one or more devices and to a power supply Standby UPS Switches instantaneously to the battery when it detects a loss of power from the wall outlet

16. 16 Factors in Choosing a UPS Amount of power needed A volt-amp (VA) is the product of the voltage and current of the electricity on a line Period of time to keep a device running Line conditioning Cost

17. 17 Connectivity Hot swappable Identical components that automatically assume the functions of their counterpart if one suffers a fault

18. 18 Topology Load balancing Automatic distribution of traffic over multiple links or processors to optimize response

19. 19 Servers Redundant Array of Inexpensive Disks (RAID) A group of hard disks is called a disk array

20. 20 RAID Level 0—Disk Stripping Simple implementation of RAID in which data are written in 64 KB blocks equally across all disks in the array

21. 21 RAID Level 1—Disk Mirroring Data from one disk are copied to another disk automatically as the information is written

22. 22 RAID Level 5—Disk Stripping with Distributed Parity Data are written in small blocks across several disks

23. 23 Server Mirroring andServer Clustering Server mirroring Fault tolerance technique in which one server duplicates the transactions and data storage of another Server clustering Fault tolerance technique that links multiple servers together to act as a single server

24. 24 Data Backup Copy of data or program files created for archiving purposes Vault Tape storage library

25. 25 Online Backups and Backup Strategy Online backups Done over the Internet Questions to ask in developing a backup strategy What kind of rotation schedule will backups follow? At what time of day or night will the backups occur? How will you verify the accuracy of the backups?

26. 26 Backup Strategy Questions to ask in developing a backup strategy (cont.) Where will backup media be stored? Who will take responsibility for ensuring that backups occurred? How long will you save backups? Where will backup and recovery documentation be stored?

27. 27 Backup Strategy Methods Full backup All data on all servers are copied to a storage medium Incremental backup Only data that have changed since the last backup are copied to a storage medium Differential backup Only data that have changed since the last backup are copied to a storage medium, and that information is then marked for subsequent backup

28. 28 Backup Rotation Scheme Specifies when and how often backups will occur

29. 29 Chapter Fourteen Network Security

30. 30 Security Audits Assessment of an organization’s security risks Should be performed at least annually and preferably quarterly What to check?

31. 31 Security Risks Social engineering Manipulating relationships to circumvent network security measures and gain access to a system Some risks associated with people Intruders or attackers using social engineering or snooping to obtain passwords An administrator incorrectly creating or configuring user IDs, groups, and their associated rights on a file server

32. 32 Security Risks Some risks associated with people (cont.) Network administrators overlooking security flaws in topology or hardware configuration Network administrators overlooking security flaws in operating system or application configuration Lack of proper documentation and communication of security policies Dishonest or disgruntled employees abusing their file and access rights An unusual computer or terminal being left logged into the network

33. 33 Security Risks Some risks associated with people (cont.) Users or administration choosing easy-to-guess passwords Authorized staff leaving computer room doors open or unlocked Staff discarding disks or backup tapes in public waste containers Administrators neglecting to remove access files and rights for former employees

34. 34 Risks Associated with Hardware and Network Design Inherent risks in network hardware and design Wireless transmission can typically be intercepted Networks that use leased lines are vulnerable to eavesdropping Repeater hubs broadcast traffic over the entire segment If they are not disabled, unused hubs, routers, or server ports can be exploited and accessed by crackers

35. 35 Risks Associated with Hardware and Network Design Inherent risks in network hardware and design (cont.) If routers are not properly configured to mask internal subnets, users on outside networks can read the private addresses Modems attached to network devices may be configured to accept incoming calls Dial-in access servers used by telecommuting or remote staff may not be carefully secured and monitored Computers hosting very sensitive data may coexist on the same subnet with computers open to the general public

36. 36 Addressing Risks Associated with People An effective security policy Typical goals for security policies Ensuring that authorized users have appropriate access to the resources they need Preventing unauthorized users from gaining access to the network, systems, programs, or data Protecting sensitive data from unauthorized access

37. 37 An Effective Security Policy Typical goals for security policies (cont.) Preventing accidental damage to hardware or software Preventing intentional damage to hardware or software Creating an environment where the network and systems can withstand and quickly recover from any type of threat Communicating each employee’s responsibilities with respect to maintaining data integrity

38. 38 Passwords Tips for making and keeping passwords secure Do not use the familiar types of passwords Do not use any word that might appear in a dictionary Make passwords longer than six characters

39. 39 Passwords Tips for making and keeping passwords secure (cont.) Choose a combination of letters and numbers Do not write down your password or share it with others Change your password at least every 90 days