Module 6.6 Networking

Internet Connectivity By default, new computers typically come with the network cards installed, the proper drivers installed, and the network card is configured to use the Dynamic Host Configuration Protocol (DHCP) to receive TCP/IP configuration information automatically. DHCP gives the configuration settings required to connect to a TCP/IP network. These values will need to be delivered to each host using DHCP, or configured manually for each network connection.

Internet Connectivity ParameterPurpose IP address The IP address identifies both the logical host and the logical network addresses. Each host on the entire network must have a unique IP address. Two devices on the same subnet must have IP addresses with the same network portion of the address. Two devices on the same subnet must have unique host portions of the IP address. Subnet mask The subnet mask identifies which portion of the IP address is the network address, and which portion is the host address. Two devices on the same subnet must be configured with the same subnet mask. Default gateway The default gateway identifies the router to which communications for remote networks are sent. The default gateway address is the IP address of the router interface on the same subnet as the local host. Without a default gateway set, most clients will be unable to communicate with hosts outside of the local subnet. DNS server The DNS server address identifies the DNS server that is used to resolve host names to IP addresses. Host nameThe host name identifies the logical name of the local system.

Internet Connectivity To edit TCP/IP properties for a network connection, open the Network Connections folder using the following methods: On the Start menu, right-click My Network Places (or Network) and select Properties. In My Network Places, click the View network connections link. In the Network and Sharing Center, click the Manage network connections link. On Windows 2000/XP, browse the Control Panel to the Network Connections icon. In the Network Connections folder, right-click the network connection and select Properties. In the Network and Sharing Center, you can also click the View status link for a connection, then click the Properties button.

Wireless networking CharacteristicDescription Devices  A wireless NIC for sending and receiving signals.  A wireless access point (AP) is the equivalent of an Ethernet hub. The wireless NICs connect to the AP, and the AP manages network communication.  A wireless bridge connects two wireless APs into a single network or connects your wireless AP to a wired network. Connection Method An ad hoc network works in peer-to-peer mode. The wireless NICs in each host communicate directly with one another. An ad hoc network is difficult to maintain for a large number of hosts because connections must be created between every other host, and special configurations are required to reach wired networks. An infrastructure wireless network employs an access point that functions like a hub on an Ethernet network. You can easily add hosts without increasing administrative efforts (scalable), and the access point can be easily connected to a wired network, allowing clients to access both wired and wireless hosts. You should implement an infrastructure network for all but the smallest of wireless networks. SSID The Service Set Identifier (SSID), also called the network name, groups wireless devices together into the same logical network. All devices on the same network must use the same SSID.

Wireless networking Specification Standard a802.11b802.11g802.11n Frequency 5.75 GHz (U- NII) 2.4 GHz (ISM) 2.4 GHz (ISM) or 5.75 GHz (U-NII) Maximum speed54 Mbps11 Mbps54 Mbps600 Mbps Maximum range150 Ft.300 Ft Ft. Channels (non- overlapped) 23 (12)11 (3) 5.75 GHz--23 (12 or 6) 2.4 GHz--11 (3 or 1) Backwards- compatibility N/ANoWith b With a/b/g, depending

Wireless networking The actual speed and maximum distance depends on several factors including obstructions (such as walls), antenna strength, and interference. The speed of data transmission decreases as the distance between the transmitter and receiver increases. You can get the maximum distance or the maximum speed, but not both. A dual band access point can use one radio to transmit at one frequency, and a different radio to transmit at a different frequency. For example, you can configure many n devices to use one radio to communicate at 5.75 GHz with a devices, and the remaining radios to use 2.4 GHz to communicate with n devices. When you configure an access point, some configuration utilities use the term mixed mode to designate a network with both n and non n clients. In this configuration, one radio transmitter is used for legacy clients, and the remaining radio transmitters are used for n clients. Many n access points can support clients running other wireless standards (802.11a/b/g). When a mix of clients using different standards are connected, the access point must disable some n features to be compatible with non n devices, which decreases the effective speed.

Wireless Security MethodDescription Open Open authentication requires that clients provide a MAC address in order to connect to the wireless network. You can use open authentication on public networks to allow any wireless client to connect to the access point. You can implement MAC address filtering to restrict access to the access point to only known (or allowed) MAC addresses. Because MAC addresses are easily spoofed, this provides little practical security. Shared key With shared secret authentication, clients and access points are configured with a shared key (passphrase). Only devices with the correct shared key can connect to the wireless network. With shared key authentication, all access points and all clients use the same authentication key. Use shared key authentication on small, private networks. Shared key authentication is relatively insecure as hashing methods used to protect the key can be easily broken x 802.1x authentication uses usernames and passwords, certificates, or devices such as smart cards to authenticate wireless clients x authentication requires the configuration of an authentication server. Use 802.1x authentication on large, private networks.

Wireless Security MethodDescription WEP Wired Equivalent Privacy was designed to provide wireless connections with the same security as wired connections. WEP has the following weaknesses:  Static Pre-shared Keys (PSK) are configured on the access point and the client and cannot be dynamically changed or exchanged without administration. As a result, every host on large networks usually uses the same key.  Because it doesn't change, the key can be captured and easily broken. The key values are short, making them easy to predict. WPA Wi-Fi Protected Access was intended as an intermediate measure to take the place of WEP while a fully secured system (802.11i) was prepared.  Uses TKIP for encryption.  Supports both Pre-shared Key (referred to as WPA-PSK or WPA Personal) and 802.1x (referred to as WPA Enterprise) authentication.  Can typically be implemented in WEP-capable devices through a software/firmware update. WPA2 or i Wi-Fi Protected Access 2 is the implementation name for wireless security that adheres to the i specifications and resolves the weaknesses inherent in WEP.  Uses Advanced Encryption Standard (AES) as the encryption method. It is similar to and more secure than TKIP, but requires special hardware for performing encryption.  Supports both Pre-shared Key (referred to as WPA2-PSK or WPA2 Personal) and 802.1x (referred to as WPA2 Enterprise) authentication.  Can use dynamic keys or pre-shared keys. Note: WPA2’s main disadvantage is that it requires new hardware for implementation.

Wireless Security MethodDescription Change the administrator account name and password The access point comes configured with a default username and password that is used to configure the access point settings. It is important to change the defaults to help prevent outsiders from breaking into your system by guessing the default username and password. Change SSID from defaults The access point comes configured with a default SSID It is important to change your SSID from the defaults or disable the SSID broadcast for further protection, this is known as SSID suppression or cloaking. Note: Even with SSID broadcast turned off, a determined hacker can still identify the SSID by analyzing wireless broadcasts. Enable MAC address filtering By specifying which MAC addresses are allowed to connect to your network, you can prevent unauthorized MAC addresses from connecting to the access point. Note: Configuring a MAC address filtering system is very time consuming and demands upkeep. Attackers can still use tools to capture packets and then retrieve valid MAC addresses. An attacker could then spoof their wireless adapter's MAC address and circumvent the filter. Disable DHCP DHCP servers dynamically assign IP addresses, gateway addresses, subnet masks, and DNS addresses whenever a computer on the wireless network starts up. Disabling DHCP on the wireless access points allows only users with a valid, static IP address in the range to connect.

Network Troubleshooting StepDescription Verify the adapter Verify that your computer has detected and properly configured the network adapter card. Make sure that the connection is enabled. Verify physical connectivity If you have a network connection in Windows, verify that the adapter can establish a physical connection to the network.  The system tray includes an icon that indicates the physical status of the connection. If the cable is unplugged, or if the NIC cannot find a connected device, you will typically see a message in the system tray.  Check the status lights on the back of the Ethernet NIC to verify the physical status. There should be a link light that is green. An unlit link light or one that is another color (like red or amber) indicates a physical connectivity problem. Verify the TCP/IP configuration If the network adapter has a physical connection, verify the TCP/IP configuration for the connection.  Use Ipconfig to view the IP address, subnet mask, and default gateway configured for the system.  If the computer is using DHCP and if you see an IP address beginning with x.x, the computer was not able to contact the DHCP server and used the APIPA feature to configure the address automatically. Verify network connectivity If the computer has a valid network connection and TCP/IP configuration values are correctly set, you can use the ping command to test connectivity with other network hosts.  If the ping test succeeds, the destination device is working. If you are still having problems, check issues with logon, resource sharing, permissions, or services.  If a ping test fails to any network device, check routers and other devices. If you can ping the host by the IP address but not the host name, then the problem is likely with the DNS configuration.

IPv6 The current IP addressing standard, version 4, will eventually run out of unique addresses, so a new system is being developed. It is named IP version 6 or IPv6. The IPv6 address is a 128-bit binary number. A sample IPv6 IP address looks like: 35BC:FA77:4898:DAFC:200C:FBBC:A007:8973. The following list describes the features of an IPv6 address: The address is made up of 32 hexadecimal numbers, organized into 8 quartets. The quartets are separated by colons. Each quartet is represented as a hexadecimal number between 0 and FFFF. Each quartet represents 16-bits of data (FFFF = ). Leading zeros can be omitted in each section. For example, the quartet 0284 could also be represented by 284. Addresses with consecutive zeros can be expressed more concisely by substituting a double-colon for the group of zeros. For example: – FEC0:0:0:0:78CD:1283:F398:23AB – FEC0::78CD:1283:F398:23AB (concise form) If an address has more than one consecutive location where one or more quartets are all zeros, only one location can be abbreviated. For example, FEC2:0:0:0:78CA:0:0:23AB could be abbreviated as: – FEC2::78CA:0:0:23AB or – FEC2:0:0:0:78CA::23AB The 128-bit address contains two parts: the prefix and the Interface IP

Homegroup A HomeGroup is a simple way of sharing resources and managing authentication to resources on a home network. The HomeGroup is created when a network interface is identified as a Home location. Be aware of the following HomeGroup details: Use the HomeGroup utility in the Control Panel to create, join, or leave a HomeGroup, manage shared libraries or change/retrieve the HomeGroup password. When creating a HomeGroup, a default password is provided. Use this password to connect other computers to the HomeGroup. To join to a HomeGroup from a computer running any edition of Windows 7: – Identify the network connection as a Home location. – Click Join Now from the HomeGroup prompt in the Taskbar, or click Join Now within the HomeGroup utility from the Control Panel. – Select which types of libraries to share. – Provide the HomeGroup password. Note: Network Discovery must be on to join to a HomeGroup. To share individual files and folders within the HomeGroup, right-click the file or folder, click Share, and select one of the following: – HomeGroup (Read) shares the file or folder with read-only privileges with the entire HomeGroup. – HomeGroup (Read/Write) shares the file or folder with read-write privileges with the entire HomeGroup.