Contents ix
January 2005
Netmask .................................................................................................................. B-4
Subnet Addressing .................................................................................................. B-5
Private IP Addresses .......... ... .................... ... ................... .... ... ................... ... ........... B-7
Single IP Address Operation Using NAT ....................................................................... B-8
MAC Addresses and Address Resolution Protocol ................................................. B-9
Related Documents ................................................................................................. B-9
Domain Name Server .............................................................................................. B-9
IP Configuration by DHCP ........... .... ... ................... ... .... ... ... ... .................... ... ... ... .... ... .. B-10
Internet Security and Firewalls .................................................................................... B-10
What is a Firewall? .................................................................................................B-11
Stateful Packet Inspection ........................... .... ... ... ... .... ... ... ... .... ... ... ... ... .... ... ...B-11
Denial of Service Attack ..................................................................................B-11
Ethernet Cabling ............. .... ... ... ... .... ... ... ................... .... ... ... ... .... ................... ... ... .... ... ...B-11
Category 5 Cable Quality ...................................................................................... B-12
Inside Twisted Pair Cables .................................................................................... B-13
Uplink Switches, Crossover Cables, and MDI/MDIX Switching ............................ B-14
Appendix C
Virtual Private Networking
What is a VPN? ............................................................................................................. C-1
What Is IPSec and How Does It Work? ......................................................................... C-2
IPSec Security Features . ................... .... ... ... ................... .... ... ... ................... .... ... ... . C-2
IPSec Components ......... ... .................... ... ................... ... .................... ... ................. C-2
Encapsulating Security Payload (ESP) ................................................................... C-3
Authentication Header (AH) ............... .... ... ... ... ... .... ... ... ... .... ... ... ... .... ................... ... . C-4
IKE Security Association .................... .................... ... ... ... .................... ... ... ... .... ....... C -4
Mode ............... ....................... ................... ....................... ...................... ........... C-5
Key Management .................................................................................................... C-6
Understand the Process Before You Begin ................................................................... C-6
VPN Process Overview ............... .... ... ... ... .... ... ... ... ... .................... ... ................... .... ... .... C-7
Network Interfaces and Addresses ......................................................................... C-7
Interface Addressing ......................................................................................... C-7
Firewalls ........................................................................................................... C-8
VPN Tunnel Between Gateways ............................................................................. C-8
VPNC IKE Security Parameters ................... ............................................................... C-10
VPNC IKE Phase I Parameters ............................................................................. C-10