Home Network Customization Willis Kim

Terminology Overview Overview Overview A broadband router combines the features of a traditional network switch, a firewall, and a DHCP server. Broadband routers are designed for convenience in setting up home networks, particularly for homes with high-speed cable modem or DSL Internet service. Broadband routers support file sharing, Internet connection sharing, and home LAN gaming. Broadband routers follow the Ethernet standard for home networking. Traditional broadband routers required Ethernet cables be run between the router, the broadband modem, and each computer on the home LAN. A broadband router combines the features of a traditional network switch, a firewall, and a DHCP server. Broadband routers are designed for convenience in setting up home networks, particularly for homes with high-speed cable modem or DSL Internet service. Broadband routers support file sharing, Internet connection sharing, and home LAN gaming. Broadband routers follow the Ethernet standard for home networking. Traditional broadband routers required Ethernet cables be run between the router, the broadband modem, and each computer on the home LAN.router switchfirewallDHCPcable modemDSLEthernetLANrouter switchfirewallDHCPcable modemDSLEthernetLAN Switch - A network switch is a small device that joins multiple computers together at a low-level network protocol layer. Technically, network switches operate at layer two (Data Link Layer) of the OSI model. Switch - A network switch is a small device that joins multiple computers together at a low-level network protocol layer. Technically, network switches operate at layer two (Data Link Layer) of the OSI model.

Terminology (con’t) DHCP allows a computer to join an IP-based network without having a pre-configured IP address. DHCP is a protocol that assigns unique IP addresses to devices, then releases and renews these addresses as devices leave and re-join the network. Internet Service Providers (ISPs) usually use DHCP to allow customers to join the Internet with minimum effort. Likewise, home network equipment like broadband routers offers DHCP support for added convenience in joining home computers to the LAN. DHCP allows a computer to join an IP-based network without having a pre-configured IP address. DHCP is a protocol that assigns unique IP addresses to devices, then releases and renews these addresses as devices leave and re-join the network. Internet Service Providers (ISPs) usually use DHCP to allow customers to join the Internet with minimum effort. Likewise, home network equipment like broadband routers offers DHCP support for added convenience in joining home computers to the LAN.broadband routersLANbroadband routersLAN DHCP environments require a DHCP server set up with the appropriate configuration parameters for the given network. Key DHCP parameters include the range or "pool" of available IP addresses, the correct subnet masks, plus gateway and name server addresses. DHCP environments require a DHCP server set up with the appropriate configuration parameters for the given network. Key DHCP parameters include the range or "pool" of available IP addresses, the correct subnet masks, plus gateway and name server addresses.subnetgatewaysubnetgateway

Terminology (con’t) An IP address is the logical address of a network adapter. The IP address uniquely identifies computers on a network. An IP address is the logical address of a network adapter. The IP address uniquely identifies computers on a network. An IP address can be private, for use on a LAN, or public, for use on the Internet or other WAN. IP addresses can be determined statically (assigned to a computer by a system administrator) or dynamically (assigned by another device on the network on demand). An IP address can be private, for use on a LAN, or public, for use on the Internet or other WAN. IP addresses can be determined statically (assigned to a computer by a system administrator) or dynamically (assigned by another device on the network on demand).

Connectivity Switch Ports Router Port (DSL Port) b is a WLAN communication standard b is one of the wireless Ethernet standards in the series. Its relatively low cost naturally resulted in many home and small business networks adopting b b LANs support a maximum data rate of 11 Mbps g extends and improves on the earlier b standard g supports a maximum bandwidth of 54 Mbps compared to the 11 Mbps of b. To achieve backward compatibility, g uses the same communication frequency range Ghz - as b.WLANEthernetLANsMbps802.11bMbps Linksys (WRT54G) transmits 28mW or 14.5dBm with a 2.2dBi omni directional antenna

Power Transmit Power – –Power (in dBm) = 10 * log10 (Signal/1mW) Radiated Power – –Antennas are passive devices that radiate radio frequency energy (RF). They do not create RF energy, but focus the energy in a specific area or direction, which increases the signal strength in that area or direction. Antenna gain is measured in: dBi relative to an isotropic radiator Total Power = Transmit + Radiated – –Effective Isotropic Radiated Power (EIRP) measured in dBm = power at antenna input [dBm] + relative antenna gain [dBi]

Distance and Data Rate

Tools Free Free –Built-in tools and utilities –NetStumbler NetStumbler –Ethereal Ethereal Not free Not free –Network General Sniffer Portable

Why customize? Increase signal strength –Using software (only on certain devices) –Using antenna Reduce noise Reduce noise –Using Japan channel standard (rest of the world)

Using software HyperWRT for Linksys WRT54G HyperWRT for Linksys WRT54G HyperWRT –Adjustable Transmit Power (from 13 to 19 dBm) –Antenna Select –13 Wireless Channels –'Boot Wait' flash protection –More Port Forwarding & Triggering Fields –More QoS Device & Application Fields –Command Shell –Startup & Firewall Scripts Use at your own risk Use at your own risk –Use web interface to load software (load with cable links)

Using software (con’t) Demonstration Demonstration –Version information in top right hand corner of initial page –Optimal settings 16dBm (Linksys original firmware set to 14.5dBm) 16dBm (Linksys original firmware set to 14.5dBm) G-Only G-Only

Using antennas Linksys antenna is omni-directional with 2.2 dBi - 360° Linksys antenna is omni-directional with 2.2 dBi - 360° Example omni-directional Antenna (Horizontal Direction) Example omni-directional Antenna (Vertical Direction)

Using antennas (con’t) Panel antenna Panel antenna –High Gain 6dBi Directional Wireless Antenna with TNC connector - 80 ° (demonstration) Example Panel Antenna (Horizontal Direction) Example Panel Antenna (Vertical Direction)

Antenna Demonstration

Using antennas (con’t) Homemade reflector antenna Homemade reflector antennareflector antennareflector antenna

Reduce noise (interference) Interference – Operating on the same frequency Interference – Operating on the same frequency Operating Channels Operating Channels –802.11b/g: Channels 1-11 for Americas, Taiwan, Thailand Channels 1-11 for Americas, Taiwan, Thailand –Out of the box Channels 1-13 for rest of the World Channels 1-13 for rest of the World –Reduces interface –Needs custom firmware and rest of the world WLAN drivers

Make sure you wireless NIC will support channels 1-13

Non-technical solutions Move Access Point into center of house Move Access Point into center of house Try to avoid wall between access point and client Try to avoid wall between access point and client Wi-Fi is basically a three-wall device Wi-Fi is basically a three-wall device

Bonus – make your AP into a client Motivation - $80 for Linksys WRT54G router and $60 for Wireless g NIC Motivation - $80 for Linksys WRT54G router and $60 for Wireless g NIC Sveasoft for Linksys WRT54G Sveasoft for Linksys WRT54G Sveasoft –Wireless Power mode selection Power mode selection Antenna selection Antenna selection Client mode (Ethernet bridging) Client mode (Ethernet bridging) Adhoc mode Adhoc mode –Advanced Routing OSPF, BGP Routing OSPF, BGP Routing –Use at your own risk

Bonus Linksys firmware is based on Linux Linksys firmware is based on Linux –HyperWRT command shell (demonstration) For example, ps, /sbin/ifconfig –a, cat /tmp/udhcpd.conf For example, ps, /sbin/ifconfig –a, cat /tmp/udhcpd.conf WEP or not to WEP WEP or not to WEP –Prevent eavesdropping (demonstration) –Increases configuration complexity

Example Topology Subnet

Backup DSL Type Max. Send Speed Max. Receive Speed Max. Distance Lines Required Phone Support ADSL800 Kbps8 Mbps 18,000 ft (5,500 m) 1Yes HDSL1.54 Mbps 12,000 ft (3,650 m) 2No VDSL16 Mbps52 Mbps 4,000 ft (1,200 m) 1Yes