11

Figure 11.10

The domain suffix search order.

Given this setup, if you typed ping server1 at the command prompt, NT would first try to locate a machine called server1.xyzcorp.com, since xyzcorp.com is my DNS domain. If a machine by this name is not found, it would try server1.houston.xyzcorp.com, server1.denver.xyzcorp.com, server1.washington.xyzcorp.com, and finally server1.USAcollege.edu, until a valid machine is found. At this point, if no machine is found, you will get an error message.

Windows Internet Name Service (WINS) Address Configuration

The WINS Address tab in the Microsoft TCP/IP Properties window enables you to configure your NT system to take advantage of any WINS servers available on the network. Additionally, it provides you more methods of Windows name resolution, such as using DNS for Windows name lookups and LMHOSTS files. For more about theses services, please see Chapter 12.

If you want to configure any of these options on your system, use the following set of procedures:

1. Make sure you are logged on as an administrative user.
2. Double-click the Network icon in the Control Panel. This will display the Network window.
3. Click the Protocols tab and then double-click TCP/IP Protocol. This will display the Microsoft TCP/IP Properties window.
4. Click the WINS Address tab. This will display the WINS configuration options for TCP/IP, shown in Figure 11.11.

   Figure 11.11

   WINS configuration options.

5. NT allows you to specify different primary and secondary WINS servers for each network card on which TCP/IP is configured. If you have only one network card installed, it will appear by default in the Adapter pick list. If you have more than one adapter, you can use the pick list to select which network card you are currently configuring.
   Enter the IP addresses for the primary WINS server and secondary WINS servers on your network.
6. If you want to allow your system to act as a WINS proxy, check the Enable WINS Proxy Agent. WINS proxy support allows your machine to provide b-node name resolution support for clients that are not configured to talk directly to the WINS server. For more on the WINS proxy and b-node name resolution, see Chapter 12.
7. Check the Enable DNS for Windows Name Resolution box if you want to use a DNS server to provide resolution for NetBIOS names. More details about using DNS for Windows name resolution can be found in Chapter 12.
   In order for this function to work, you must have your system configured to use at least one DNS server. See the section titled "Configuring Windows NT to use Existing DNS Servers," earlier in this chapter for information about setting up NT to use DNS servers. If you want to use an LMHOSTS file for Windows name resolution, check the box Enable LMHOSTS lookup. You can use the Import LMHOSTS button to import an existing LMHOSTS file. The LMHOSTS file is located in the %SystemRoot%\system32\drivers\etc directory. By default, this file does not exist, but Microsoft does provide a sample file called LMHOSTS.SAM as a template for creating your own. For more information on LMHOSTS files, see Chapter 14.
8. If your network uses NetBIOS scopes for limiting NetBIOS traffic over TCP/IP, you can enter the scope into the Scope ID field. Typically this field is left blank. The NetBIOS scope is a string that gets appended to the computers NetBIOS name. You can communicate only with computers that have the same NetBIOS scope as your system. The NetBIOS scope allows you to effectively have two physical computers on the network with the same NetBIOS name since the NetBIOS name is actually a concatenation of the computer's name and it's NetBIOS scope.

Enabling IP Routing

Windows NT Server supports static IP routing (IP forwarding) on multihomed systems. Until the 4.0 release, NT Server was capable of static IP routing only. This allowed you to configure NT to work with other static IP routers on the network. Under this configuration, you need to use the route command to create static routes. However, with NT Server 4.0, Microsoft includes a Routing Information Protocol (RIP) agent that allows NT Server to collect RIP information from other routers on the network.

To configure your NT Server as an IP router, use the following procedure.

1. Make sure you are logged on as an administrative user.
2. Double-click the Network icon in the Control Panel. This will display the Network window.
3. Click the Protocols tab. This will display a list of currently installed network services.
4. Double-click the TCP/IP Protocol. This will bring up the Microsoft TCP/IP Properties page. Then click on the IP Routing tab. The IP Routing tab is shown in Figure 11.12.
5. If you want to enable static IP routing (IP forwarding) click the Enable IP Forwarding box.
6. Click OK. This will return you to the Network control panel window.

Figure 11.12

Enabling IP static IP routing.

If you also want to enable dynamic RIP routing, you must install the RIP for Internet Protocol service. Continue with the following procedure to install this service as well:

1. Click the Services tab. This will display a list of all currently installed services.
2. Click the Add button. NT will generate a list of all available services for installation.
3. Scroll down the list and click the RIP for Internet Protocol entry. This is shown in Figure 11.13.

   Figure 11.13

   Selecting the RIP for Internet Protocol entry.

4. Click OK.
5. You might be required to provide a path to the Windows NT Server distribution media so NT can install the necessary software components.
   NT will copy files from the distribution media to the local system directory.
   Once it has finished copying the necessary files, you will be returned to the Network window.
6. From the Network control panel window, click the Close button. Any changes you made will not take effect until you restart your system. You will be asked if you want to restart your system.

Installing Simple TCP/IP Services

Windows NT includes an optional service called Simple TCP/IP Services. This service allows Windows NT respond to a number of network utilities that are somewhat prevalent in the UNIX world. For most environments, these utilities provide no real functionality.

Simple TCP/IP services are all based on UDP and provide support for

• Chargen: When the chargen (character generator) service receives any input, it generates and returns a stream of data and sends it back to the sender. There is no relationship between the data received by the chargen service and the data it return to the sender, although the data is usually a recognizable pattern. Use of chargen is defined in RFC 864.
• Daytime: When it receives input, this service, defined in RFC 867, returns the current date and time.
• Discard: This service accepts any incoming data and then throws it away. It does not return anything to the sender. Discard is defined in RFC 863.
• Echo: Echo is defined in RFC 862. It takes UDP packets directed at it and returns them to the sender.

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  NOTE:

  Although it might seem that the Ping diagnostic utility would probably use the Echo service, it does not. You do note need to install the Echo service to support Ping. The echo service uses UDP packets and operates at a much higher level than Ping, which uses ICMP packets.

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• Quote: Quote is a quote-of-the-day service. When the quote service receives an incoming packet, it discards this packet and then returns a quote from a predefined quote file. The default quote file is installed in %SystemRoot%\system32\drivers\etc. This file can be modified to add new quotes so long as the quotes are less than 512 characters. The quote utility is defined in RFC 865.

Diagnostic Utilities

Microsoft has included a number of TCP/IP diagnostic utilities with Windows NT. Many of these utilities, such as ping and tracert, are functionally identical to common implementations on other platforms, including most UNIX systems. Other utilities, such as nbtstat, are more specific to Windows environments and do not have direct analogues on non-Windows systems.

All of the diagnostic utilities listed in this section are automatically installed when you installed TCP/IP on your system. They are all located in the %SystemRoot%\system32 directory.

arp

The arp command is used to display or modify the IP address to physical network address lookup table maintained by Windows NT. This table is called the address resolution protocol (ARP) table.

The syntax for the arp command is arp -a [IP_addr] [-N [if_addr]] arp -d IP_addr [if_addr] arp -s IP_addr mac_addr [if_addr]

-a displays the current ARP table. If inet_addr is included, the IP and physical addresses for only the specified computer are displayed. If there is more than one network interface using TCP/IP, the ARP table for each is displayed.

-N if_addr displays the ARP entries for the network interface specified by if_addr.

-d deletes the ARP entry specified by inet_addr.

-s is used to manually add an entry in the ARP table. Typically, ARP entries age out of the table after a period of time. However, when you manually add an ARP entry, the entry will be permanent.

mac_addr specifies the physical address of the network adapter. It is represented as eight hexadecimal pairs separated by dashes.

IP_addr specifies an IP address.

if_addr indicates the address of the network adapter on which the ARP table should be updated.

hostname

The hostname command returns the name of the computer as defined in the DNS tab of the TCP/IP configuration window. There are no options to this command.

ipconfig

The ipconfig utility is useful for getting a quick look at a system's TCP/IP configuration. It is especially useful when your systems receives its IP configuration from a DHCP server.

The syntax for the ipconfig command is

ipconfig [/all | /release [adapter] | renew [adapter]]

If you run ipconfig without any switch options, it returns the IP address, subnet mask and default gateway for all network adapters bound with TCP/IP.

/all causes ipconfig to return additional IP configuration information for all network adapters running TCP/IP. This information includes the TCP/IP hostname, list of all DNS servers, node type, NetBIOS scope ID, state of IP routing (IP forwarding) on your system, state of WINS proxy on your system, and if your system will use DNS to provide NetBIOS name resolution. Additionally, for each network adapter using TCP/IP, it will provide the physical address of the adapter, whether or not it gets its information from a DHCP server, its IP address (or IP addresses if it's logically multihomed), its subnet mask, default gateway, and any WINS servers it uses.

/renew [adapter] is useful only when your system acquires its IP information dynamically from a DHCP server. If you use the switch without specifying an adapter, it will attempt to renew the DHCP lease for all adapters. If you only want to renew the lease for a specific network adapter, you can do that by typing its name. If you do not get your IP information from a DHCP server but you use this switch, it will return an error.

/release [adapter] is functionally the opposite of the /renew switch. If you use the switch without specifying an adapter, it will attempt to release the DHCP lease for all adapters. If you only want to release the lease for a specific network adapter, you can do that by typing its name.

nbtstat

The nbtstat command is used to display the status of NetBIOS over TCP/IP (NetBT).

The syntax for the nbtstat command is

nbtstat [-a hostname] [-A IP_addr] [-c] [-n] [-R] [-r] [-S] [-s] [interval]

-a displays the remote computer's NetBIOS name table given its NetBIOS hostname.

-A displays the remote computer's NetBIOS name table given its IP address.

-c displays the NetBIOS name cache of the local computer, including the name and IP address for each entry.

-n displays the NetBIOS names of the local computer.

-R purges the NetBIOS name cache on the local computer and reloads the LMHOSTS file.

-r displays statistics for Windows name resolution. If you are using a WINS server for Windows name resolution, this option returns the number of names resolved by broadcast and the number of names resolved by a WINS server.

-S displays statistics and session information for workstation and server services. This information is listed by IP address.

-s displays statistics and session information for workstation and server services. It lists information by hostname if the IP address is listed in your HOSTS file. Otherwise, it is listed by IP address.

interval, if specified, will result in nbtstat continuously redisplaying the statistics, pausing interval seconds between each update. If no interval is specified, the information will be displayed once.

netstat

netstat can be used to examine the statistics for all TCP, IP, and UDP connections.

The syntax for the netstat command is

netstat [-a] [-e] [-n] [-s] [-p protocol] [-r] [interval]

If you run netstat without any switch options, it displays all active TCP connections.

-a tells netstat to display all the current connections and listening ports.

-e displays the network statistics. These statistics are cumulative since the last time the computer was reset. Included are the total number of bytes, the number of unicast and non-unicast packets, the number of discarded packets and the number of errors.

-n results in (by default) netstat displaying the IP hostname and port names. This switch causes netstat to instead display the IP address and port number.

-s displays the statistics for each of the protocols, TCP, IP, ICMP, and UDP. You can combine this with the -p protocol option if you only want the information for a single protocol.

-p protocol specifies that connections and statistics should be shown only for a specific protocol. Valid values for protocol are TCP, UDP, IP, and ICMP.

-r causes netstat to display the active routes from the routing table.

interval results in netstat continuously updating the statistics, pausing interval seconds between each update. If no interval is specified, the information will be displayed once.

ping

ping is one of the fundamental diagnostic utilities. It can be used to verify if a host is reachable. When troubleshooting TCP/IP connectivity problems, ping should be the first tool to use. ping uses the Internet control message protocol (ICMP) echo packets to do its job.

The syntax for the ping command is

ping [-t] [-a] [-n count] [-l length] [-f] [-i ttl] [-v tos] [-r count] [-s count] [[-j host_list] | [-k host_list]] [-w timeout] destination_list

By default, ping will send four 64-byte ICMP packets with a one-second pause between each packet.

-t indicates that ping should continuously send packets until you press Ctrl+c.

-a is used to resolve the IP address to the DNS hostname.

-n count indicates that ping should send counts ICMP packets. The default is 4.

-l length indicates the length of the ICMP packet. The contents of the ICMP packet is a periodic sequence of alphabetic characters. The default packet size is 64 bytes, and the maximum is 8,192. However, Ethernet networks have a maximum data size of 1,512 bytes. Choosing a value larger than this will cause the packets to become fragmented.

-f sets the do-not-fragment flag on the packet. If you use the -l switch to indicate a packet size that is larger than the maximum packet size of one of the routers the packet must pass through, the packet will be returned with an error. You can be use this switch along with the -l option to discover the largest packet you can send from your computer to a remote host without it being fragmented.

-i ttl sets the time to live (ttl) field on the packets. The ttl is the maximum number of router hops the packet can go through before being discarded. Valid values are between 1 and 255. The default is 30.

-v tos sets the Type Of Service field to the value specified by tos.

-r count records the route of the outgoing and returning ICMP packets in the Record Route field. A minimum of 1 to a maximum of 9 hosts must be specified by count.

-s count specifies the time stamp for the number of hops specified by count.

-j host_list routes packets by means of the list of hosts specified by host_list. Consecutive hosts may be separated by intermediate gateways (loose source routed). The maximum number of hosts allowed is 9.

-k host_list routes packets by means of the list of hosts specified by host_list. Consecutive hosts may not be separated by intermediate gateways (strict source routed). The maximum number of hosts permitted is 9.

-w timeout specifies a time-out interval in milliseconds.

destination_list specifies the remote hosts to ping.

route

The route command is used to manage the local TCP/IP route table.

The syntax for the route command is

route [-f] [print|add|delete|change [destination] [MASK netmask] [gateway]]

-f flushes the routing table of all entries and resets it to its default values. If this option is not used alone, the route table is flushed before performing the other command.

print, used without destination, displays the entire route table. When used with destination prints the route table entry for that destination.

add adds a permanent static route.

delete deletes the route specified by destination.

change modifies an existing route specified by destination.

destination specifies the destination in the route table, and expressed in standard IP dot notation.

MASK if present, specifies that the next parameter is the netmask parameter.

netmask, when used with the add or modify command, specifies the subnet mask to use for the route entry.

gateway, when used with the add or modify command, specifies the IP gateway to use when forwarding packets to destination.

tracert

tracert is an extremely useful utility that determines the path taken between your system and a target system. If you are experiencing connectivity problems, this can be useful for pinpointing the location of the problem.

tracert uses Internet Control Message Protocol (ICMP) echo packets to accomplish its job. First tracert determines the number of router hops to its destination. Then it sends a number of ICMP echo packets equal to the hop count. On the first packet, tracert sets the time-to-live (TTL) to 1. On each successive packet, tracert increments the TTL by 1. Each time a packet goes through a router, the router decrements the TTL byWhen the TTL reaches 0, most routers send a message back to the sender indicating the packet has been discarded. This means the first echo packet sent (with a TTL of 1) will be returned by the first router. The second echo packet (with a TTL of 2) will be returned by the second router, and so on.

The syntax for the route command is

tracert [-d] [-h max_hops] [-j host_list] [-w timeout] destination

-d specifies not to resolve IP addresses to host names, which is done by default.

-h max_hops specifies the maximum number of hops to search for destination.

-j host_list specifies loose source route along host_list.

-w timeout specifies a time-out interval for each packet in milliseconds.

destination specifies the hostname or IP address of the destination computer.

Connectivity Utilities

Microsoft included a couple of standard TCP/IP connectivity utilities with Windows NT. These utilities include Telnet, FTP, finger, and TFTP.

Telnet

Windows NT includes a graphical Telnet utility that can be used to connect to any system running a standard telnet server, as described in RFC 854. The Telnet utility can be found in the Accessories program group or can be started by typing telnet at the Run prompt.

---

NOTE:

Windows NT Server does not include a Telnet server component. If you want to use Telnet to connect to your NT Server, there are a couple of third-party companies that make Telnet server components.

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The Telnet is fairly simple, but does include features such as logging the Telnet session to file, vt-100/ansi emulation, and configurable screen settings.

FTP

Windows NT includes a relatively simple, command-line FTP client. This utility can be invoked from the Run prompt, or from the command line by typing FTP. Once in the FTP utility, you can get a simple level of help by typing help or ? at the ftp> prompt. FTP file transfers are governed by standards defined in RFC 959.

For information on installing the FTP server that comes with Windows NT, see Chapter 28, Windows NT as an Internet Server.

finger

Also included with Windows NT is a finger client utility. This command-line utility can be used to get user information from any system running a standard finger service.

The finger command can be used in one of two ways:

• finger @hostname
• finger username@hostname

The first syntax usually returns a list of users logged onto the hostname's system. The second syntax usually gives information about the specified user, such as full name, office phone number, or address. Additionally, many finger servers accept partial user names and will return all matches.

---

NOTE:

Windows NT Server does not include a finger server service. A finger server service for NT is available from the European Microsoft Windows NT Academic Centre (EMWAC). EMWAC can be contacted at http://www.emwac.ed.ac.uk.

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TFTP

The trivial file transfer protocol (TFTP) command allows you to transfer files to or from a computer running a TFTP server, as defined in RFC 783.

The syntax for the tftp command is tftp [-i] host [GET | PUT] source [destination]

-i indicates a binary file transfer. You must specify this switch when transferring binary files.

host is the name of the remote machine.

GET transfers the file from host to the local machine.

PUT transfers the file from the local machine to host.

source is the full name of the file to be transferred.

destination is the name the transferred file will have when the transfer is complete. If destination is not included, the destination filename will be the same as the source.

Summary

This chapter presented a look at TCP/IP on the Windows NT platform. It included how Microsoft implemented TCP/IP on NT, as well as the steps they have taken to ensure that Windows NT can take full advantage of standards-based networking through the implementation of services such as WINS, DHCP, DNS, LPR/LPD, and other TCP/IP protocols.

You also saw how TCP/IP integration enhances connectivity with Windows for Workgroups and Windows 95 clients through a robust implementation of NetBIOS over TCP/IP. The chapter continued with an explanation of how to install and configure TCP/IP on Windows NT Server, including an explanation of how to install and configure additional TCP/IP-related services, such as IP Routing and simple TCP/IP services.