Network Configuration: Lecture 3 - LAN Setup

System Administration

Module 2: Lecture 3:

Network Configuration: LAN Setup

10BaseT Ethernet Setup

To connect a 10BaseT Ethernet network:

• Install a network interface card (NIC) into each computer (host)
• Connect each NIC to a hub or switch, using unshielded twisted pair (UTP) cabling

Hub:

• Every frame received by a hub is reproduced on all of it’s ports

Switch (or Cable/DSL Router):

• Every frame received by a switch is examined, and the correct port is determined for the frame
• A Cable/DSL also provides network address translation (NAT)

LAN network cable connection

Generally LAN cables are called Unshielded Twisted Pair. There are two cable systems.

• Straight cable.
• Crossed cable.

The straight and crossed cable systems are shown below:

 802.11g Wireless Setup

 To setup a 802.11g wireless network:

• Install an 802.11g (or 802.11b) NIC into each host
• Plug a wireless router or base station into your Internet connection (e.g. cable modem)
• Configure the SSID and security protocols on the wireless router and each of the NICs
• e.g. WPA encryption, and specify the key

  Ad Hoc Wireless Networks

 If you have only a few hosts (2-3), you can create an ad hoc network

• This type of network does not have a base station (or wireless router)
• The hosts communicate directly with one another

 Wireless Networks Comment

A wireless network connection is often not useful for a desktop PC

• For this reason, wireless routers typically contain a few Ethernet ports
• It is typical to have desktop PCs wired, and notebooks and PDAs will have wireless
• e.g. Notebooks with 802.11g and PDAs with 802.11b

 Packet Sniffers

 Packet sniffers are a useful tool for exploration of networking

• They can also be used by network programmers to diagnose packet format errors

They typically examine many protocols

• This includes the header informationm e.g. Wireless, Ethernet, TCP/IP, HTTP

Some common packet sniffers are:

• Ethereal (Linux/Mac/Windows, multi-protocol)
• TCPDump (Linux/Windows, TCP/IP)
• Kismet (Linux, wireless)

 Ethereal Tutorial

Here is how to sniff packets using Ethereal:

• Start Ethereal
• Select the correct network interface
• Start capturing packets, stop when done
• Select a packet from the list
• Examine the packet hierarchy and header information, such as:
• Ethernet or wireless frame headers
• IP datagram headers
• TCP datagram headers
• SMTP message

Module 2_Lecture 3 - Network Configuration - LAN Setup