OSI Model

TIMING + SYNC

Processing

• __ OSI: Physical

  __ PDU: [ BITS ]

  __ TCP/IP: Network Access

  __ Protocol Suite: [ Framerelay | ATM ]

DESTINATION + PHYSICAL ADDRESS

Data

• __ OSI: Data

  __ PDU: [ FRAME ]

  __ TCP/IP: Network Access

  __ Protocol suite: ethernet | wifi

[IP] DESTINATION + SOURCE LOGICAL NETWORK ADDRESS

Need

• __ OSI: Network

  __ PDU: [ PACKET ]

  __ TCP/IP: Internet

  __ Protocol suite: [ IPv4 | IPv6 ]

[PORT] DESTINATION + SOURCE PROCESS NUMBER

To

• __ OSI: Transport

  __ PDU: [ SEGMENT ]

  __ TCP/IP: Trasport

  __ Protocol suite: [ TCP | UDP ]

ENCODED APPLICATION DATA

Seem

• __ OSI: Session

  __ PDU: [ DATA ]

  __ TCP/IP: Applications

  __ Protocol suite: [ DNS | PNP | SNMP ]

People

• __ OSI: Presentation

  __ PDU: [ DATA ]

  __ TCP/IP: Applications

All

• __ OSI: Application

  __ PDU: [ DATA ]

  __ TCP/IP: Applications

  __ Protocol suite: [ HTTP | FTP | SMTP ]

Sub-Nets

Hosts double each increment of a CIDR

• Always subtract 2 from host total:

  • Network ID - First Address

  ---

  • Broadcast - Last Address

x.0.0.0

255.x.0.0

255.255.x.0

255.255.255.x

Basic linux bash scripting

Create a series of commands

ex.

>> append

echo "hey again again" >> hey.txt

nano

• simple txt editor

nano

ctrl + x
save: y

Network commands bash

ping

• can I talk to ip-address

ping 192.168.15.1

arp -a

• associate ip addresses with mac addresses

arp -a

netstat -ano

• figure out if this machine is talking to anyone else
• active connections running on machine

netstat -ano

route

• tells you where traffic is exiting

route