13. Network Problems and Solutions

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13. Network Problems and Solutions
Networking and Telecommunications
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Cables

• Problems - crosstalk, emi, rfi, close to
  interference
• Solution - twisted pair (higher grade), shielded
  wire, fiber optic, run cables carefully, dont
  violate rules (too long cable runs), use proper
  standard cables, keep way from sources of
  interference (flourecent lights)
• Problems - improper ends, loose connections
• Solution - crimping tool, wire testers

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Server/Client

• Problems - hardware failures (hard drives, cpu
  board, nic, etc)
• Solutions - UPS, disk mirroring, raid,
  redundancy, spare parts, maintenance contracts
• Problems - software failures (NOS)
• Solutions- patches, new versions, backups (tape)

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Operation Room

• Problems - heat/humidity, power, fire, physical
  security
• Solutions - air conditioner/humidifier, UPS,
  sprinklers, locks, swipe cards, motion
  detectors

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Networking

• Problems - high traffic volumes, slowness
• Solutions - use bridges, switches, or a higher
  speed lan technology (like 10baseT to 100baseT)
• Problems - ports on hub/switches not talking to
  NICs
• Solutions - check setting on port (10 vs.100,
  full vs. half duplex, auto-negotiate)
• Problems collisions
• Solutions Non-contention Network Architecture
  (token ring, FDDI) or Full Duplex Fast Ethernet,
  use switches

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Lan Monitoring Tools

• Watch traffic and packets
• History, snmp
• Watch hubs, switches, routers
• Watch and Repair
• Reset, UP/Down Port

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Network Security
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Typical Problems

• Viruses (I love You/Melissa/Sircam virus) -
  floppy/email attachments, human intervention to
  spread. Anti-Virus software (detect and
  clean)...keep up-to-date.
• Worms (sendmail, code red, nimda, Nachia, SoBig)
  - automatic spreading using vunerabilities in
  the operating system
• Trojan horses (mimic other programs...like login
  screens)

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Typical Problems (cont.)

• DOS attacks (denial of service) - yahoo/microsoft
  problems. DDOS (distributed DOS)
• ip spoofing - fake source ip address to appear
  local (block via router and ACL)
• Gain root/adminstrator access
• Packet sniffing
• SPAM (unwanted junk email)- more of an annoyance
• Spyware-pop-ups, redirected webpages

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What Hackers like to do?

• Deface, take over systems, backdoors, root kits,
  launching pad to attack others, keep hidden
• Networks are a virtual petri dish for breeding
  computer viruses"

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How to combat?

• Boot from server, disable floppy (diskless
  workstations), boot rom chips
• Dont open email attachments!
• User permissions/passwords on server, ACL (access
  control lists), file/directory permissions
• Router ACL- control access, filter packets, limit
  bandwidth (dorms)
• Share only what data is needed from server
• to client
• Frequent backups, data encryption

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How to combat? (cont.)

• Authorization/authentication
• Audit trails/logs
• Call back systems via modems, one time password
  cards (enigma or secure-id)
• Fiber optic cables
• Firewalls
• IDS (Intrusion detection systems), sends alerts
  (logs, email, pager, etc.)
• Physical locks, swipe cards, motion detectors,
  login/passwords

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How to combat? (cont.)

• Outside intruders (hackers), and internal
  concerns
• Security patches, OS up to date
• bulletins, mailings lists, newsgroups
• Virus scanning software (up to date)
• Be careful of wireless lans and other shared
  media (hubs)
• Use of VPN
• Anti-Spam Software (spam assassin)
• Ethics
• Fight Spyware using software like Adaware, or
  Spybot

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"Multiple Lines of Defense !!!"

• "Multiple Lines of Defense !!!"
• "Multiple Lines of Defense !!!"
• "Multiple Lines of Defense !!!"
• "Multiple Lines of Defense !!!"
• "Multiple Lines of Defense !!!"
• "Multiple Lines of Defense !!!"
• "Multiple Lines of Defense !!!"
• "Multiple Lines of Defense !!!"
• "Multiple Lines of Defense !!!"

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Multiple Lines of Defense !!
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• THE END!!