U2.1 Cables, Hubs, Sniffers

1. Carrier Sense
   1. before sending, device checks to see if there is another device using network, if yes, it waits
2. multiple access
   1. any device can use network when it is free
3. collision detection
   1. after detecting collision, wait a random delay
      1. if collision detected again, wait 2x as long and check (called "expontential backoff")

1. 10BASE 5, 10 Mbps, 500m

1. 10BASE2, 10Mbps, 200m

1. 10BASE-T, 100-BASE -T, T=twisted pair
   1. Cat 1 telephone
   2. Cat 3, 10Mbps
   3. Cat 5, 100Mbps
   4. Cat5e, 1000Mbps

1. Used for token ring, good for high interference

1. 1000 Mbps or higher

1. Not type of cabling, but often used instead of. 11-150Mbps

1. information leakage
2. integrity violation
3. denial of service
4. illegitimate use
5. safeguards
   1. run cable through protective trunking
   2. lockable, dedicated network closets
   3. add electromagnetic shielding to cabling
   4. run cabling through trunking with pressurized gas, have alarms for pressure loss

1. dumb
2. intelligent
   1. regenerate signals for long network cables
   2. monitor congestion, send alarms
   3. remote monitoring

Anexos:

• U2.1 Cables, Hubs, Sniffers - Hub Diagram

1. non-promiscuous
   1. only listens to traffic targeted for that device
2. promiscuous
   1. listens to all traffice on the network

1. method 1
   1. 1.send large volume of packets to non-existing network address
   2. 2. send an ICMP request to suspect device. If device is sniffing, it will be overwhelmed.
2. method 2
   1. 1. Send packet to unused IP address on network
   2. 2. Sniff network to see if any devices try to resolve DNS name

1. coaxial cable
2. build network by daisychaining nodes
   1. computers connect directly to network cable
3. vulnerabilities
   1. when one cable is damaged, the whole network fails
   2. all devices on network receive data
   3. easy to attach addtional devices

1. connects devices to network via hub (see note)

   Anexos:

   • U2.1 Cables,Hubs,Sniffers- Thin Ethernet
2. vulnerabilities
   1. all devices on network receive data (hub broadcasts)
   2. easy to attach additional devices