04/14/10 1 13. Network Problems and Solutions Networking and Telecommunications
04/14/10 2
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
04/14/10 3
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)
04/14/10 4
Operation Room
Problems - heat/humidity, power, fire, physical security
Solutions - air conditioner/humidifier, UPS, sprinklers, locks, swipe cards, motion detectors
04/14/10 6
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
04/14/10 7
Watch traffic and packets History, snmp Watch hubs, switches, routers Watch and Repair Reset, UP/Down Port
Lan Monitoring Tools
04/14/10 9
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)
04/14/10 10
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.)
04/14/10 11
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"
04/14/10 12
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
04/14/10 13
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
04/14/10 14
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.)
04/14/10 15
"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 !!!"