Internet Sharing

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Internet Sharing - With
Without Wires
Dave Botherway, Melbourne PC User
Group
July 2007
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W H Y ? ?

• WHY Share ? a) Maximising that
  old PC b) Parallel working c) File
  Printer Sharing d) Multi-User Household
• Easier said than done . . . .
• Why the topic ? a) What to buy
  ? b) How to connect ?
• It didnt work ! ! Where Next ?

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Needed A G E N D A . . . .

• I / P Addressing Concepts
• Simple Networking
• DHCP Dynamic Host Config Program
• Internet Gateways
• DNS - Domain Name Server
• I C S - Internet Connection Sharing Sw
• Router / Modem Sharing
• Wireless Connectivity

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TCP / IP Addressing

• Telephone every Phone WW, a unique
  Number expanded via private PABX extensions
• Internet every device WW, a unique
  address expanded via private Gateway extensions
• Example - 240 . 12 . 23 . 81 (IPv4
  method) max 255.255.255.255 -gt 4B
  addresses but not all usable -gt major
  shortage . .
• Two solutions a) private network
  gateways with NAT similar to a PABX b) IP
  v6, as now available in Vista

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Address Types

• Highest level (Class A) 201. nnn.nnn.nnn
  256 available, each with 16m extensions
• Next level (Class B) 201. 82.
  nnn.nnn 65k available, each with 65k
  extensions
• Next level (Class C) 201. 82. 115.
  nnn 16m available, each with 256 extensions
• Not enough, so PABX/Gateway concepts used
• Reserved Gateway addresses via NAT,
  DHCP 10. nnn. nnn. nnn 127. 0 . 0 . 0
  (internal loopback) 192. 168. nnn. nnn

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Simple I/P Addressing - Local Network
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Bridging to the Outside World, via a
Gateway
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External Addressing, via Gateway NAT
ting
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But we use URLs - gt Domain Name Server
( DNS )
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Thus for EACH pc, we need . . .

• TCP / IP Protocol s/w ( these days, a
  default )
• I P Address, either fixed or Gateway
  DHCP
• Gateway address where do I go next ?
• DNS location

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Two PCs - One Modem
to ISP
Internet Connection Sharing - ICS
PC needs 2 LAN cards, else USB ex Modem
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XP Help Panel - I C S
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Three PCs - One Modem
to ISP
Single Port Modem Cable or ADSL
Router - with DHCP (Not just Hub)
RJ45
Wireless
Router / Gateway
Direct RJ 45 Cables
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D-Link 4P Wireless Router
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Three PCs - One Modem
ISP provides external IP , DNS
to ISP
Single Port Modem
Router - with DHCP (Not just Hub)
RJ45
Wireless
Router / Gateway
Direct RJ 45 Cables
Router provides internal IP, NAT
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VISTA Help Panel - Routers
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Combo Modem Three PCs
to ISP Cable or ADSL
Multi-Port Wireless . Modem
Wireless
Modem-Router-GW
Direct RJ 45 Cables
Wi Fi Modem / Router - with DHCP
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Combination Modem / Router
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Comparison - ICS vs Router

• With ICS, base computer must be on for
  other PCs to have access . . . - and more
  complex to setup / diagnose.
• With Router, extra setups - NOT
  dependant on one ICS PC - configured via
  Browser - easier than ICS . . . once
  understood . . .
• Wireless Option a) ideal for Laptops
  (becoming Std) b) may solve building / wiring
  issues c) imposes Security issues,
  attention

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Diagnostics

• Use ipconfig.exe to find IP addresses,
  GW setups, DNS etc
• PING other PCs to determine connectivity
• Check firewalls in case blocking
• Wireless setup a) initially No Firewall,
  No Security b) caution open to The Street .
  . . c) add Security / WEP ASAP d) maybe
  suppress SSID broadcast ?
• Have fun - if needed, get MelbPc support
  Users helping Users

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IpConfig Output
Ping Output
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Questions
Dave Botherway, Melbourne PC User
Group
July 2007