CIS 225

Lecture 17 - Network Architecture & Configuration

7 Layer OSI Network Model

• Application
• Presentation
• Session
• Transport - TCP/UDP
• Network - IPv4/IPv6
• Data Link - Ethernet
• Physical - 100BASE-T

Physical - 100BASE-T

Image Source: Wikipedia

Data Link - Ethernet

Image Source: Wikipedia

Network - IPv4

IPv4 vs. IPv6

IPv4: 32 bit Addresses
2³² = 4,294,967,296

IPv6: 128 bit Addresses
2¹²⁸ = 340,282,366,920,938,463,463,
374,607,431,768,211,456
or 340 Undecillion addresses

Network - IPv6

Image Source: Wikipedia

Network Interfaces

• Localhost
• Ethernet Adapter
• Wireless Adapter

Localhost

• a.k.a Loopback Adapter (lo)
• IP Address: 127.0.0.1
• DNS Name: localhost
• Defined in Software
• Allows a system to access itself via nework protocols

Network Adapters

• Physical hardware connections to a network
• Includes Wired (Ethernet) and Wireless adapters
• Each adapter may have 1 or more IP addresses

Windows Network Adapters
Device Manager

Windows Network Adapters
Network Connections

Ubuntu Network Adapters
/etc/hosts

/etc/network/interfaces

Ubuntu Network Adapters

IP Addresses

• Unique Identifier on a Network
• Used for packet routing
• 3 common configurations
  • Automatic - DHCP
  • Manual - Static IP Addresses
  • Automatic Private IP Addressing (APIPA)

IP Address Components

• IP Address - The identifier of this computer
• Subnet Mask - The subnet this computer belongs to
• Default Gateway - The IP address of the "way out"

Reserved IP Address Sections

• 192.168.0.0 - 192.168.255.254 (255.255.0.0)
• 172.16.0.0 - 172.31.255.254 (255.240.0.0)
• 10.0.0.0 - 10.255.255.254 (255.0.0.0)
• 169.254.0.0 - 169.254.255.254 (APIPA)

Dynamic Host Configuration Protocol (DHCP)

Image Source: Tech Juice

Ubuntu - dhclient

Manual Configuration

• Manually enter IP address information for hosts
• Normally used on servers and core network devices
• More control, but more work to make changes

Automatic Private IP Addressing (APIPA)

• When all else fails, your system will assign an address that is non-routable
• If your IP is like 169.254.x.x then something is not working correctly

Windows IP Configuration

Ubuntu IP Configuration

Windows Diagnostic Commands

• ping - contact IP addresses and DNS names
• tracert - trace route between hosts
• ipconfig - access IP configuration

ipconfig

• ipconfig /release
• ipconfig /renew
• ipconfig /all
• ipconfig /flushdns
• ipconfig /displaydns

Ubuntu Diagnostic Commands

• ping - contact IP addresses and DNS names
• traceroute - trace route between hosts
• ifconfig - access IP configuration
• mtr - combine ping and traceroute

Transport - TCP

Transport - UDP

TCP vs. UDP

Ports

• Individual connection points for each application on a computer
• 65535 possible ports (2¹⁶)
• Around 250 are "well known" ports with widely accepted uses for incoming connections
• Outgoing connections use high numbered "ephemeral" ports

Well Known Ports
/etc/services

• 21 - FTP
• 22 - SSH
• 25 - SMTP
• 80 - HTTP
• 443 - HTTPS
• 3389 - Remote Desktop

Windows - Sysinternals TCPView

Ubuntu - netstat

Reading

• Windows 8 - Chapter 13
• Ubuntu Unleashed - Chapter 21

Assignments

• Lab 7 - Software Configuration & Security: Due 10/28 @ 11:59 PM
• Lab 8 - Network Configuration & Sharing: Due 11/4 @ 11:59 PM
• Exam 2 - Wednesday 11/6