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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, don’t 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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Watch traffic and packets History, snmp Watch hubs, switches, routers Watch and Repair Reset, UP/Down Port

Lan Monitoring Tools

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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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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

Typical Problems (cont.)

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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 Don’t 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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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

How to combat? (cont.)

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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!!