NETGEAR CG814M manual Private IP Addresses

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Reference Manual for the Model CG814M Wireless Cable Modem Gateway

Table 6-2. Netmask Formats

255.255.255.0 /24

255.255.255.128 /25

255.255.255.192 /26

255.255.255.224 /27

255.255.255.240 /28

255.255.255.248 /29

255.255.255.252 /30

255.255.255.254 /31

255.255.255.255 /32

NETGEAR strongly recommends that you configure all hosts on a LAN segment to use the same netmask for the following reasons:

So that hosts recognize local IP broadcast packets

When a device broadcasts to its segment neighbors, it uses a destination address of the local network address with all ones for the host address. In order for this scheme to work, all devices on the segment must agree on which bits comprise the host address.

So that a local router or bridge recognizes which addresses are local and which are remote

Private IP Addresses

If your local network is isolated from the Internet (for example, when using NAT), you can assign any IP addresses to the hosts without problems. However, the IANA has reserved the following three blocks of IP addresses specifically for private networks:

10.0.0.0- 10.255.255.255

172.16.0.0- 172.31.255.255

192.168.0.0 - 192.168.255.255

NETGEAR recommends that you choose your private network number from this range. The DHCP server of the CG814M Gateway is preconfigured to automatically assign private addresses.

Regardless of your particular situation, do not create an arbitrary IP address; always follow the guidelines explained here. For more information about address assignment, refer to RFC 1597, Address Allocation for Private Internets, and RFC 1466, Guidelines for Management of IP Address Space. The Internet Engineering Task Force (IETF) publishes RFCs on its Web site at www.ietf.org.

Networks, Routing, and Firewall Basics

B-7

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Contents NETGEAR, Inc Trademarks World Wide Web Page Contents USB Appendix a Appendix C Contents Contents Typographical Conventions About This ManualAudience Technical Support Special Message FormatsChapter Introduction Key FeaturesAbout the CG814M Gateway Built-in Cable Modem802.11b Standards-based Wireless Networking Powerful, True FirewallContent Filtering Protocol Support Configurable Auto Uplink Ethernet ConnectionUSB Port Easy Installation and Management Firewall’s Front Panel What’s in the Box?LED Descriptions CG814M Gateway Rear Panel Gateway’s Rear PanelIntroduction What You Will Need Before You Begin Connecting the Gateway to the InternetLAN Hardware Requirements Computer RequirementsWhere Do I Get the Internet Configuration Parameters? LAN Configuration RequirementsInternet Configuration Requirements Connecting the Gateway to the Internet Record Your Internet Connection Information Connecting to Your Computer Connecting the CG814M GatewayUSB EthernetWireless Connecting to your Cable Service ProviderLog in to the Gateway Connecting the Power AdapterLogin window opens as shown in -3below Connect to the Internet Configuration Connecting the CG814M Gateway to the InternetConnecting the Gateway to the Internet Connecting the Gateway to the Internet Connecting the Gateway to the Internet Security Chapter Wireless ConfigurationConsiderations For a Wireless Network Placement and Range Wireless SettingsRestricting Wireless Access by MAC Address Wireless SettingsConfiguring Wired Equivalent Privacy WEP Wireless Configuration Wireless Configuration Chapter Protecting Your Network Protecting Access to Your CG814M GatewayChanging the Built-In Password Set Password menu Blocking Keywords, Sites, and ServicesBlock Keywords and Domains Click on the Block Sites link of the Content Filtering menu Proxy Blocking ServicesCookies Port BlockingPort Blocking menu Port ForwardingTo forward inbound traffic Considerations for Port Forwarding Port TriggeringTo configure Port Triggering Respond to Ping on Internet WAN Port Setting Up a Default DMZ HostProtecting Your Network Network Status Information Chapter Managing Your NetworkThis screen shows the following parameters Viewing Gateway StatusMenu 3.2 Router Status Fields Connection screen Connection StatusCurrent System Time Configuring LAN IP SettingsLAN IP Setup Use router as Dhcp server DhcpLogs menu Viewing and Emailing Logged InformationEnabling Logs Event E-mail Notification Erasing ConfigurationDiagnostics menu Running Diagnostic UtilitiesManaging Your Network Basic Functions Chapter TroubleshootingLocal Link LEDs Not On Power LED Not OnTest LED Stays On Cable Link LED Not On Troubleshooting the Web Configuration InterfaceTesting the LAN Path to Your Gateway Troubleshooting the ISP ConnectionTroubleshooting a TCP/IP Network Using a Ping Utility Testing the Path from Your PC to a Remote Device Troubleshooting TCP/IP Appendix a Technical SpecificationsTechnical Specifications Related Publications Basic Router Concepts Appendix B Networks, Routing, and Firewall BasicsIP Addresses and the Internet What is a Router?Routing Information Protocol Three Main Address Classes Equals NetmaskExample of Subnetting a Class B Address Subnet AddressingNetmask Notation Translation Table for One Octet Private IP Addresses Single IP Address Operation Using NAT Single IP Address Operation Using NATRelated Documents MAC Addresses and Address Resolution ProtocolDomain Name Server IP Configuration by DhcpInternet Security and Firewalls Stateful Packet Inspection What is a Firewall?Denial of Service Attack Wireless Network Configuration Wireless NetworkingAd-hoc Mode Peer-to-Peer Workgroup Infrastructure ModeAuthentication and WEP Encryption Extended Service Set Identification EssidTable B-1 802.11b Radio Frequency Channels Wireless Channel SelectionEthernet Cabling Uplink Switches and Crossover CablesCable Quality Preparing Your Computers for TCP/IP Networking Appendix C Preparing Your NetworkInstall or Verify Windows Networking Components Configuring Windows 95, 98, and ME for TCP/IP NetworkingPreparing Your Network Selecting Windows’ Internet Access Method Enabling Dhcp to Automatically Configure TCP/IP SettingsVerifying TCP/IP Properties Configuring Windows NT, 2000 or XP for IP NetworkingMacOS 8.6 or Configuring the Macintosh for TCP/IP NetworkingMacOS Verifying TCP/IP Properties for Macintosh Computers Verifying the Readiness of Your Internet Account What Is Your Configuration Information?Mail.xxx.yyy.com Preparing Your Network Restarting the Network Glossary Networks See Network Address Translation Connection