Home Network Home Network CustomizationCustomization

Willis KimWillis Kim

TerminologyTerminology

• OverviewOverview• A broadband A broadband router router combines the features of a combines the features of a

traditional network traditional network switchswitch, a , a firewallfirewall, and a , and a DHCPDHCP server. server. Broadband routers are designed for convenience in Broadband routers are designed for convenience in setting up home networks, particularly for homes with setting up home networks, particularly for homes with high-speed high-speed cable modemcable modem or or DSLDSL Internet service. Internet service. Broadband routers support file sharing, Internet Broadband routers support file sharing, Internet connection sharing, and home LAN gaming. Broadband connection sharing, and home LAN gaming. Broadband routers follow the routers follow the EthernetEthernet standard for home standard for home networking. Traditional broadband routers required networking. Traditional broadband routers required Ethernet cables be run between the router, the Ethernet cables be run between the router, the broadband modem, and each computer on the home broadband modem, and each computer on the home LANLAN. .

• Switch - A network switch is a small device that joins Switch - A network switch is a small device that joins multiple computers together at a low-level network multiple computers together at a low-level network protocol layer. Technically, network switches operate at protocol layer. Technically, network switches operate at layer two (Data Link Layer) of the OSI model.layer two (Data Link Layer) of the OSI model.

ConnectivityConnectivity

Switch Ports

Router Port(DSL Port)

802.11b is a WLAN communication standard. 802.11b is one of the wireless Ethernet standards in the 802.11 series. Its relatively low cost naturally resulted in many home and small business networks adopting 802.11b. 802.11b LANs support a maximum data rate of 11 Mbps. 802.11g extends and improves on the earlier 802.11b standard. 802.11g supports a maximum bandwidth of 54 Mbps compared to the 11 Mbps of 802.11b. To achieve backward compatibility, 802.11g uses the same communication frequency range - 2.4 Ghz - as 802.11b.

Linksys (WRT54G) transmits 28mW or 14.5dBm with a 2.2dBi omni directional antenna

PowerPower

• 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 RateDistance and Data Rate

ToolsTools

• FreeFree– Built-in tools and utilitiesBuilt-in tools and utilities– NetStumblerNetStumbler– EtherealEthereal

• Not freeNot free– Network General Sniffer PortableNetwork General Sniffer Portable

Why customize?Why customize?

Increase signal strengthIncrease signal strength– Using software (only on certain devices)Using software (only on certain devices)– Using antennaUsing antenna

• Reduce noiseReduce noise– Using Japan channel standard (rest of Using Japan channel standard (rest of

the world)the world)

Using softwareUsing software

• HyperWRT for Linksys WRT54GHyperWRT for Linksys WRT54G– Adjustable Transmit Power (from 13 to 19 dBm)Adjustable Transmit Power (from 13 to 19 dBm)– Antenna SelectAntenna Select– 13 Wireless Channels 13 Wireless Channels – 'Boot Wait' flash protection'Boot Wait' flash protection– More Port Forwarding & Triggering Fields More Port Forwarding & Triggering Fields – More QoS Device & Application FieldsMore QoS Device & Application Fields– Command Shell Command Shell – Startup & Firewall ScriptsStartup & Firewall Scripts

• Use at your own riskUse at your own risk– Use web interface to load software (load with cable Use web interface to load software (load with cable

links)links)

Using software (con’t)Using software (con’t)

• DemonstrationDemonstration– Version information in top right hand Version information in top right hand

corner of initial pagecorner of initial page– Optimal settingsOptimal settings

•16dBm (Linksys original firmware set to 16dBm (Linksys original firmware set to 14.5dBm)14.5dBm)

•G-OnlyG-Only

Using antennasUsing antennas

• Linksys antenna is omni-directional Linksys antenna is omni-directional with 2.2 dBi - 360with 2.2 dBi - 360°°

Example omni-directionalAntenna (Horizontal Direction)

Example omni-directionalAntenna (Vertical Direction)

Using antennas (con’t)Using antennas (con’t)

• Panel antennaPanel antenna– High Gain 6dBi Directional Wireless High Gain 6dBi Directional Wireless

Antenna with TNC connector - 80 Antenna with TNC connector - 80 ° ° (demonstration)(demonstration)Example Panel Antenna

(Horizontal Direction)Example Panel Antenna(Vertical Direction)

Antenna DemonstrationAntenna Demonstration

Using antennas (con’t)Using antennas (con’t)

• Homemade reflector antennaHomemade reflector antenna

Reduce noise (interference)Reduce noise (interference)

• Interference – Operating on the same Interference – Operating on the same frequencyfrequency

• Operating ChannelsOperating Channels– 802.11b/g: 802.11b/g:

•Channels 1-11 for Americas, Taiwan, ThailandChannels 1-11 for Americas, Taiwan, Thailand– Out of the boxOut of the box

•Channels 1-13 for rest of the WorldChannels 1-13 for rest of the World– Reduces interfaceReduces interface– Needs custom firmware and rest of the world Needs custom firmware and rest of the world

WLAN driversWLAN drivers

Make sure you wireless NIC will Make sure you wireless NIC will support channels 1-13support channels 1-13

Non-technical solutionsNon-technical solutions

• Move Access Point into center of Move Access Point into center of househouse

• Try to avoid wall between access Try to avoid wall between access point and clientpoint and client

• Wi-Fi is basically a three-wall deviceWi-Fi is basically a three-wall device

Bonus – make your AP into a Bonus – make your AP into a clientclient• Motivation - $80 for Linksys WRT54G Motivation - $80 for Linksys WRT54G

router and $60 for Wireless g NICrouter and $60 for Wireless g NIC• Sveasoft for Linksys WRT54GSveasoft for Linksys WRT54G

– Wireless Wireless • Power mode selection Power mode selection • Antenna selection Antenna selection • Client mode (Ethernet bridging) Client mode (Ethernet bridging) • Adhoc modeAdhoc mode

– Advanced RoutingAdvanced Routing• OSPF, BGP RoutingOSPF, BGP Routing

– Use at your own riskUse at your own risk

Bonus Bonus

• Linksys firmware is based on Linux Linksys firmware is based on Linux – HyperWRT command shell HyperWRT command shell

(demonstration)(demonstration)•For example, ps, /sbin/ifconfig –a, cat For example, ps, /sbin/ifconfig –a, cat

/tmp/udhcpd.conf/tmp/udhcpd.conf

• WEP or not to WEPWEP or not to WEP– Prevent eavesdropping (demonstration)Prevent eavesdropping (demonstration)– Increases configuration complexityIncreases configuration complexity

Example TopologyExample Topology

VDSL via POTS

Router and Wireless Access Point 802.11b/g192.168.1.1 (gateway)

Channel 13 – 2.472 GHz

SSID1

VDSL modem

`

Computer, DHCP

`

Fixed, 192.168.100.201

ComputerFixed, 192.168.1.200

SSID2

Wireless Bridge 802.11b192.168.1.225

SSID1

Bridge and Wireless Access Point 802.11b192.168.1.11

Channel 11 – 2.462 GHzSSID2

Wireless Bridge 802.11g192.168.1.50

SSID1

Subnet 255.255.255.0

BackupBackup

DSL TypeMax. Send

Speed

Max. Receive Speed

Max. Distance

Lines Required

Phone Support

ADSL 800 Kbps 8 Mbps18,000 ft(5,500 m)

1 Yes

HDSL 1.54 Mbps 1.54 Mbps12,000 ft(3,650 m)

2 No

VDSL 16 Mbps 52 Mbps4,000 ft

(1,200 m)1 Yes