Ensuring Integrity and Availability

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Ensuring Integrity and Availability

• Dean (3rd), Chapter 13

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Overview

• Characteristics of network that keep data safe
  from loss or damage
• Protect enterprise-wide network from viruses
• Network- and system-level fault-tolerance
  techniques
• Network backup and recovery strategies
• Disaster recovery plan

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Integrity and Availability

• Integrity soundness of a networks programs,
  data, services, devices, and connections.
• Availability how consistently and reliably files
  and systems can be accessed by authorized
  personnel

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Guidelines for Protecting Network

• Allow only network administrators to create or
  modify NOS and application system files
• Monitor network for unauthorized access or
  changes
• Record authorized system changes
• Install redundant components
• Perform regular health checks on the network
• Check system performance, error logs, and the
  system log book regularly
• Keep backups, boot disks, and emergency repair
  disks current and available
• Implement and enforce security and disaster
  recovery policies

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Viruses and Malicious Software

• A virus is a program that replicates itself with
  the intent to infect more computers
• Other unwanted and potentially destructive
  programs are called viruses, but technically do
  not meet the criteria used to define a virus
• Program that disguises itself as something useful
  but actually harms your system is called a Trojan
  horse

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Types of Malicious Software

• Viruses
• Boot sector viruses
• Macro viruses
• File-infected viruses
• Network viruses
• Worms
• Trojan horse
• Bots

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Virus Characteristics

• Encryption
• Stealth
• Polymorphism
• Time-dependence

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Virus Protection

• Virus symptoms
• Antivirus software
• Antivirus policies

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Virus Symptoms

• Unexplained increases in file sizes
• Significant, unexplained decline in system
  performance
• Unusual error messages
• Significant, unexpected loss of system memory
• Fluctuations in display quality

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Antivirus Software

• Antivirus software should perform
• Signature scanning
• Integrity checking
• Monitoring of unexpected file changes
• Regular updates and modifications
• Consistently report only valid viruses
• Heuristic scanning -- most fallible

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Antivirus Policies

• Virus detection and cleaning software that
  regularly scans for viruses
• Users not allowed to alter or disable
• Users know what to do
• Antivirus team appointed maintaining antivirus
  measures
• Users prohibited from installing any unauthorized
  software
• System-wide alerts issued

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Virus Hoaxes

• Type of rumor consists of a false alert about a
  dangerous, new virus
• Verify a possible hoax

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Fault Tolerance

• Capacity for a system to continue performing
  despite an unexpected hardware or software
  malfunction
• Failure is a deviation from a specified level of
  system performance for a given period of time
• Fault involves the malfunction of one component
  of a system

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Sources of Faults and Failures

• Environment
• Analyze the physical environment in which your
  devices operate
• Power flaws

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Power Flaws

• SurgeA momentary increase in voltage
• NoiseA fluctuation in voltage levels
• BrownoutA momentary decrease in voltage
• BlackoutA complete power loss

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Uninterruptible Power Supplies (UPSs)

• Prevents A/C power from harming device or
  interrupting its services
• Standby UPS provides continuous voltage to a
  device by switching
• Online UPS providing power to a network device
  through its battery

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Examples of UPSs
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Selecting Emergency Power Source

• Which UPS is right for your network
• Amount of power needed
• Period of time to keep a device running
• Line conditioning
• Cost
• Generators
• If your organization cannot withstand a power
  loss you might consider investing in an
  electrical generator for your building

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Inclusion of UPS and Generator
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Topology and Connectivity

• Each physical topology inherently assumes certain
  advantages and disadvantages
• Supplying multiple paths data can use to travel
  from any one point to another

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Network with VPN
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Firewall with T1 Connection
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Redundant T1 Connections
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Fault Tolerance (continued)

• Servers

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Server Mirroring

• Mirroring is a fault-tolerance technique in which
  one device or component duplicates the activities
  of another
• In server mirroring, one server continually
  duplicates the transactions and data storage of
  another

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Redundant NICs
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Clustering

• Fault-tolerance technique that links multiple
  servers together to act as a single server

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Fault Tolerance (continued)
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Storage

• Redundant Array of Independent (or Inexpensive)
  Disks (RAID)
• Collection of disks that provide fault tolerance
  for shared data and applications
• Hardware RAID
• Set of disks and a separate disk controller
• Software RAID
• Software to implement and control RAID

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Fault Tolerance (continued)

• Storage

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RAID Levels

• RAID Level 0Disk Striping
• Data is written in 64 KB blocks equally across
  all disks in the array
• RAID Level 1Disk Mirroring
• Provides redundancy through a process called disk
  mirroring
• RAID Level 3Disk Striping with Parity ECC
• Involves disk striping with a special error
  correction code (ECC)
• RAID Level 5Disk Striping with Distributed
  Parity
• Highly fault-tolerant
• Data is written in small blocks across several
  disks
• Parity error checking information is distributed
  among the disks

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RAID 0Data Striping
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RAID 1Disk Mirroring
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Parity and Parity Bit
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RAID 3Striping Parity Disk
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RAID 5Striping Data Parity
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Network Attached Storage

• Specialized storage device or group of storage
  devices that provides centralized fault-tolerant
  data storage for a network

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Network Attached Storage
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Storage Area Networks (SANs)

• Distinct networks of storage devices that
  communicate directly with each other and with
  other networks

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Storage Area Network
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Data Backup

• A backup is a copy of data or program files
  created for archiving or safekeeping
• Tape Backups
• Copying data to a magnetic tape

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Tape Media
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Data Backup (continued)

• Tape Backups (continued)

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Select Appropriate Tape Backup

• Sufficient storage capacity
• Proven to be reliable
• Data error-checking techniques
• Is the system quick enough
• Tape drive, software, and media cost
• Hardware and software be compatible with existing
  network
• Frequent manual intervention
• Accommodate your networks growth

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Online Backups

• Companies on the Internet now offer to back up
  data over the Internet

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Backup Strategy

• What data must be backed up
• What kind of rotation schedule
• When will the backups occur
• How will you verify
• Where will backup media be stored
• Who will take responsibility
• How long will you save backups
• Where will backup and recovery documentation be
  stored

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Data Backup (continued)

• Backup Strategy (continued)

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Different Backup Methods

• Full backup
• Incremental backup
• Differential backup

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Backup Generations
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Disaster Recovery

• A disaster recovery plan should identify a
  disaster recovery team
• Contact for emergency coordinators
• Which data and servers are being backed up
• Network topology, redundancy, and agreements
• Regular strategies for testing
• A plan for managing the crisis

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Chapter Summary

• Integrity refers to the soundness of your
  networks files, systems, and connections
• Several basic measures can be employed to protect
  data and systems
• A virus is a program that replicates itself
• Boot sector viruses position their code in the
  boot sector
• Macro viruses take the form of a macro

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Chapter Summary (continued)

• File-infected viruses attach themselves to
  executable files
• Network viruses take advantage of network
  protocols
• A virus bot is a virus that spreads automatically
  between systems
• Worms are not technically viruses
• A Trojan horse claims to do something useful but
  instead harms

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Chapter Summary (continued)

• Any type of virus may have additional
  characteristics that make it harder to detect and
  eliminate
• A good antivirus program should be able to detect
  viruses through signature scanning, integrity
  checking, and heuristic scanning
• Antivirus software is merely one piece of the
  puzzle in protecting your network

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Chapter Summary (continued)

• A virus hoax is a false alert about a dangerous,
  new virus
• A failure is a deviation from a specified level
  of system performance for a given period of time

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Chapter Summary (continued)

• A fault is the malfunction of one component of a
  system
• Fault tolerance is a systems capacity to
  continue performing despite an unexpected
  hardware or software malfunction

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Chapter Summary (continued)

• Networks cannot tolerate power loss or less than
  optimal power
• A UPS is a battery power source directly attached
  to one or more devices and to a power supply
• A standby UPS provides continuous voltage to a
  device by switching

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Chapter Summary (continued)

• An online UPS uses the A/C power from the wall
  outlet to continuously charge its battery
• For utmost fault tolerance in power supply, a
  generator is necessary

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Chapter Summary (continued)

• Network topologies such as a full mesh WAN or a
  star-based LAN with a parallel backbone offer the
  greatest fault tolerance
• Hot swappable components can be changed (or
  swapped) while a machine is still running (hot)
• Critical servers often contain redundant
  components

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Chapter Summary (continued)

• Utilizing a second, identical server to duplicate
  the transactions and data storage of one server
  is called server mirroring
• Server clustering links multiple servers together
  to act as a single server

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Chapter Summary (continued)

• An important storage redundancy feature is a
  Redundant Array of Independent (or Inexpensive)
  Disks (RAID)
• Network attached storage (NAS) is a dedicated
  storage device
• A storage area network (SAN) is a distinct
  network of multiple storage devices and servers

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Chapter Summary (continued)

• A backup is a copy of data or program files
  created for archiving or safekeeping
• A popular, economical method for backing up
  networked systems is tape backup
• You can also back up data over the Internet

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Chapter Summary (continued)

• The aim of a good backup rotation scheme is to
  provide excellent data reliability
• Every organization should have a disaster
  recovery team