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Archives for December 2009
Thursday, 31 December 2009
Sunday, 20 December 2009
0 National Do Not Call (NDNC) Registry – START DND to 1909
Informations from Author: Smith Solace
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The National Do Not Call Registry (NDNC Registry) is setup to curb the Unsolicited Commercial Communication (UCC), which is any telecommunications service message, which is transmitted for the purpose of informing about or soliciting or promoting any commercial transaction in relation to goods, investments or services which a subscriber opts not to receive.
The NDNC Registry will be a database having the list of all telephone numbers of the subscribers who do not want to receive unsolicited messages. Telephone subscriber (land line or mobile) who does not wish to receive UCC, can register their telephone number with their telecom service provider for inclusion in the NDNC. Telecom Service Provider shall upload the telephone number to the NDNC within 45 days of receipt. The Telemarketer will have to verify their calling telephone numbers list with the NDNC registry before making a call.
An amount of Rs 500/- per call/message for the first call has been prescribed to discourage telemarketers who make calls to numbers registered in Do Not Call list. The second call will have a fine of Rs 1000/- and third time the line will be disconnected. The defaulter telemarketer will face disconnection of telecom service.
Each user need to register their number with their communication provider such as BSNL, Airtel, Reliance, Hutch etc. in order to register their cell number of land line number with the NDNC Registry. The provider may provide website interface or SMS interface for registering your number in NDNC Registry. Check with your provider for the details.
Saturday, 5 December 2009
0 THE TCP/IP FAMILY TREE
AUTHOR: SMITH SOLACE
The Transmission Control Protocol (TCP) and the Internet Protocol (IP) together form the basis for TCP/IP, a low-level driver that lets computers talk to each other using a network of almost any size. The Internet is connected using TCP/IP as its foundation.
TCP/IP was proposed in 1973. Nine years later, in 1983, a standardized version of the protocol was developed and adopted for wide-area use. In 1983, it also became mandatory that all connections to ARPAnet, the Department of Defense’s predecessor to today’s Internet, be made with TCP/IP.
TCP/IP was developed to solve several problems in moving data from point A to point B. The most important requirement was to guarantee delivery of data on a network that might be under attack from a foreign power. Because the Department of Defense (DoD) developed the Internet, this requirement was paramount and fairly predictable. If an enemy were to attack the military’s computer systems and networks, data must continue to flow, secure and unhampered. The other established requirements were that data be moved efficiently and that its arrival be verified - yet the sending machine might not have any of the same operating characteristics as the receiving machine. TCP and IP both perform unique and vital functions that solve all the problems in moving data between machines over networks.
Transmission Control Protocol
TCP is the transmission layer of the protocol. Its primary function is to ensure reliable and verifiable data exchange between different hosts across a network. TCP performs its tasks by breaking data into manageable pieces and then wrapping the pieces with information called a header that routes the data to its final destination. TCP on the receiving machine then puts all the pieces back together, just as they were before the data was sent. The wrapped and bundled pieces are called datagrams.
The primary pieces of information in the TCP header are the source and destination port numbers, a sequence number for the datagram, and a checksum. Port numbers allow the data to be sent back and forth to the correct process running on each computer. (We cover ports in more detail later in this chapter.) The sequence number lets TCP reassemble the datagrams in the correct order. The checksum lets the protocol determine whether the data received is the data that was sent. The checksum calculates a number by adding all the octets of a datagram; this number is then inserted into the datagram’s header. The receiving computer performs the same calculation, and if the two calculations do not match, an error occurred somewhere along the line, and the datagram is resent.
After the TCP header is inserted into the datagram, TCP passes the datagram to the IP protocol to be routed to its final destinationshows the layout of a datagram with its TCP header structure.
Internet Protocol
IP is the network layer portion of TCP/IP. IP actually moves data from point A to point B across a network. This movement of data is called routing, and that’s really all IP does. (We cover routing in a bit more detail later in this chapter.) IP is typically considered unreliable, meaning that nothing guarantees that the data it routes will even arrive at its destination, much less in the order it was sent. IP relies on TCP to determine whether the data arrived successfully at its destination and to retransmit the data if it hasn’t.
To route data, IP inserts its own header into the datagram after it receives it from TCP. The contents of the IP header are the source and destination addresses, another checksum, and the protocol number. The header informs routers (or gateways) along the way of the datagram’s final destination. for a layout of a datagram complete with its TCP and IP headers. The IP header portion has a gray background.
The Transmission Control Protocol (TCP) and the Internet Protocol (IP) together form the basis for TCP/IP, a low-level driver that lets computers talk to each other using a network of almost any size. The Internet is connected using TCP/IP as its foundation.
TCP/IP was proposed in 1973. Nine years later, in 1983, a standardized version of the protocol was developed and adopted for wide-area use. In 1983, it also became mandatory that all connections to ARPAnet, the Department of Defense’s predecessor to today’s Internet, be made with TCP/IP.
TCP/IP was developed to solve several problems in moving data from point A to point B. The most important requirement was to guarantee delivery of data on a network that might be under attack from a foreign power. Because the Department of Defense (DoD) developed the Internet, this requirement was paramount and fairly predictable. If an enemy were to attack the military’s computer systems and networks, data must continue to flow, secure and unhampered. The other established requirements were that data be moved efficiently and that its arrival be verified - yet the sending machine might not have any of the same operating characteristics as the receiving machine. TCP and IP both perform unique and vital functions that solve all the problems in moving data between machines over networks.
Transmission Control Protocol
TCP is the transmission layer of the protocol. Its primary function is to ensure reliable and verifiable data exchange between different hosts across a network. TCP performs its tasks by breaking data into manageable pieces and then wrapping the pieces with information called a header that routes the data to its final destination. TCP on the receiving machine then puts all the pieces back together, just as they were before the data was sent. The wrapped and bundled pieces are called datagrams.
The primary pieces of information in the TCP header are the source and destination port numbers, a sequence number for the datagram, and a checksum. Port numbers allow the data to be sent back and forth to the correct process running on each computer. (We cover ports in more detail later in this chapter.) The sequence number lets TCP reassemble the datagrams in the correct order. The checksum lets the protocol determine whether the data received is the data that was sent. The checksum calculates a number by adding all the octets of a datagram; this number is then inserted into the datagram’s header. The receiving computer performs the same calculation, and if the two calculations do not match, an error occurred somewhere along the line, and the datagram is resent.
After the TCP header is inserted into the datagram, TCP passes the datagram to the IP protocol to be routed to its final destinationshows the layout of a datagram with its TCP header structure.
Internet Protocol
IP is the network layer portion of TCP/IP. IP actually moves data from point A to point B across a network. This movement of data is called routing, and that’s really all IP does. (We cover routing in a bit more detail later in this chapter.) IP is typically considered unreliable, meaning that nothing guarantees that the data it routes will even arrive at its destination, much less in the order it was sent. IP relies on TCP to determine whether the data arrived successfully at its destination and to retransmit the data if it hasn’t.
To route data, IP inserts its own header into the datagram after it receives it from TCP. The contents of the IP header are the source and destination addresses, another checksum, and the protocol number. The header informs routers (or gateways) along the way of the datagram’s final destination. for a layout of a datagram complete with its TCP and IP headers. The IP header portion has a gray background.
0 NEW TCP IP PROTOCOLS
The TCP/IP family consists of several other protocols typically referred to as application protocols, which are specialized protocols that use TCP/IP as their foundation. With the ever-growing popularity of the Internet, new application protocols are being developed at a blistering pace. Let’s look at a few:
• Address Resolution Protocol (ARP) helps link a physical media access control address (an Ethernet address) with a node’s associated IP address.
• Internet Control Message Protocol (ICMP) works at the IP network layer level and helps with network layer management and control, ensuring that errors are noted and corrected.
• Universal Datagram Protocol (UDP) is a connectionless protocol that is generally considered an unreliable way to send data across a network because it does not guarantee that the data sent will ever arrive at its destination. UDP is, however, a very efficient and fast way to send data because it does not have to connect and disconnect to send it, thus reducing network overhead.
• Simple Network Management Protocol (SNMP) makes it possible to collect information from network devices and lets network administrators manipulate configuration settings.
• Simple Mail Transfer Protocol (SMTP) allows for basic e-mail service across a network.
• Network News Transfer Protocol (NNTP) enables the propagation of public discussion forums.
• Telnet is a terminal emulation program that lets a user log on to a computer from a remote location.
• Internet Relay Chat (IRC) lets numerous users connect to a server, where they can all "chat" using real-time text-based messages.
• The World Wide Web, or the Web, as it’s commonly called, is a hypertext transfer protocol that makes it possible to display documents containing clickable links to other documents.
• File Transfer Protocol (FTP) lets users transfer files across a network.
• Finger lets one user look up contact information about another user by asking a specific system for that information.
• Whois lets a user query the global Whois databases for contact and location information about a user or domain name.
• Gopher lets a user search for documents and files containing specific keywords and phrases.
• Archie searches for files by file name or parts of file names.
• RealAudio allows for the transmission and receipt of prerecorded and live audio across a network.
• VDOLive enables the transmission and receipt of prerecorded and live video across a network.
Ports and Sockets
Data sent from one computer to another on a TCP/IP network is sent to a port on the receiving computer. A port is like a person at a particular address. You can certainly send postal mail to any address you desire; however, you usually address the mail to a particular person or department so that it gets into the right hands. Ports let the correct process receive the data directly.
All ports are assigned unique numbers ranging from 0 to 32768. Today, many ports are numerically standardized and preassigned. For example, SMTP mail servers normally run on port 25, and Web servers normally run on port 80. TCP/IP uses a modifiable lookup table, usually stored in a file called Services, to determine the correct port for the correct data type. Ports may be queried by name or number. Ports can sometimes be defined on the fly by a program that facilitates other actions.
TCP uses the IP address of the receiving computer, along with the correct port number, to build the socket address. We discuss sockets later in this section; for now, just understand that sockets are low-level tools used to read and write data from, not to be confused with ports.
TCP creates a connection to the receiving computer using the socket address. Although TCP sometimes stays connected while data is being sent, staying connected while transferring data is not necessary and in fact is not the norm. After the data is sent, TCP simply disconnects from the socket. Furthermore, datagrams can arrive at the destination at different times and out of sequence. As I mentioned earlier, TCP/IP receives the datagrams and puts them together in the right order, complete with an acknowledgment to the sender.
Sockets are low-level interfaces to the TCP/IP family that were initially developed for Unix operating systems (the BSD Unix operating system was the first). Sockets are like files on your hard drive; you can read from them and write to them, which is exactly how they are used in a TCP/IP networking environment. A socket is created either to await a connection and any subsequent data exchange or to create a connection and initiate a data exchange. When a server uses a socket to wait for an incoming connection, it is a passive socket; when a client uses a socket to initiate a connection, it is an active socket. The only difference between active and passive sockets is the way different software packages use them.
0 TCP IP GENERATION NEXT
The Future of TCP/IP - IP Next Generation
As you may have gathered, TCP/IP is an ever-evolving family of protocols. With the explosion of the Internet, we are seeing some of the limitations of this protocol suite. One problem in particular is that we will soon run out of usable IP addresses under the current specification, with so many new connections to the Internet being built and installed every day. Another major issue is security. Both of these serious problems are being addressed by various consortia that are quickly finding the answers. Let’s look at one of the foremost proposed solutions because it is likely to become a integral part of the protocol suite in the very near future.
The current version of the IP protocol is version 4, or IPv4, and the next generation, IPv6 or IPng (IP next generation), is set to become formally adopted. IPng was recommended by the IPng Area Directors of the Internet Engineering Task Force (IETF) at the Toronto IETF meeting held on July 25, 1994, as documented in RFC 1752, "The Recommendation for the IP Next Generation Protocol." (Request for Comments (RFCs) are a standard way to propose and debate the merits of any significant change or modification to a standard involving TCP/IP and the Internet in an open forum.) IPng was approved by the Internet Engineering Steering Group and made a Proposed Standard on November 17, 1994. The core set of IPng protocols was made an official IETF Proposed Standard on September 18, 1995.
IPng can be installed as a normal software upgrade to Internet devices and is interoperable with the current version of IPv4 found in today’s TCP/IP protocol. IPng is designed to run well on high performance networks, such as Asynchronous Transfer Mode (ATM), and at the same time is still efficient for low-bandwidth networks, such as wireless networks. In addition, IPng provides a platform for new Internet functions that will be required in the near future.
IPng was designed to be an evolutionary step up from IPv4 but not to be a radical step away from it. Functions that work in IPv4 were kept in the IPng specification, and likewise, the functions that didn’t work were removed. The changes from IPv4 to IPng fall primarily into the following categories:
• Expanded routing and addressing capabilities.
• IPng increases the IP address size from 32 bits to 128 bits, which obviously supports more levels of addressing and a much greater number of addressable nodes. IPng also facilitates a simpler means of automatically configuring IP addresses.
• A new type of address, the anycast address, is defined in IPng. An anycast address identifies nodes; a packet sent to an anycast address is delivered to one of the nodes. Using anycast addresses in the IPng source route lets nodes control the path along which their traffic flows. IPng address types are discussed further later in this section.
• Header format simplification - Some IPv4 header fields have been dropped or made optional to reduce the common processing cost of packet handling and to keep the bandwidth cost of the IPng header as low as possible despite the increased size of the addresses. Even though the IPng addresses are four times longer than the IPv4 addresses, the IPng header is only twice the size of the IPv4 header.
• Improved support for options - Changes in the way IP header options are encoded allow for more efficient forwarding, less stringent limits on the length of options, and greater flexibility for introducing new options.
• Quality-of-service capabilities - A new capability enables the labeling of packets belonging to particular traffic flows for which the sender requests special handling, such as nondefault quality of service or real-time service.
• Authentication and privacy capabilities - IPng defines extensions that provide support for authentication, data integrity, and confidentiality. These definitions are included as a basic element of IPng and will be included in all implementations.
There are three basic types of IPng addresses: unicast, anycast, and multicast. Unicast addresses identify a single interface. Anycast addresses identify a set of interfaces so that a packet sent to an anycast address is delivered to one member of the set. Multicast addresses identify groups of interfaces, so that a packet sent to a multicast address is delivered to all the interfaces in the group. Multicast addresses in IPng supersede broadcast addresses.
IPng supports 128-bit addresses, or four times the number of bits as the IPv4 32-bit addresses. This 128-bit addressing scheme is several times the size of the current IPv4 32-bit address space - 4 billion squared times the current space, or 340,282,366,920,938,463,463,374,607,431,768,211,456 bits.
The Internet has a number of major security problems and lacks effective privacy and authentication mechanisms below the application layer. IPng corrects these shortcomings with two integrated options that provide security services. These two options may be used separately or together to provide different levels of security to different users. This feature is very important because different user communities have different security requirements.
The first security mechanism, the IPng Authentication Header, is an extension header that gives IPng datagrams authentication and integrity without confidentiality. Although the extension is algorithm independent and will support many different authentication techniques, the use of an MD5 security system has been proposed to help ensure this feature’s interoperability within the Internet.
The IPng Authentication Header can eliminate a significant class of network attacks, including host-masquerading attacks. Using the IPng Authentication Header is particularly important when source routing is used with IPng because of the known risks in IP source routing. Its placement at the Internet layer can help provide host origin authentication to those upper-layer protocols and services that currently lack meaningful protection schemes.
The second security extension header provided with IPng is the IPng Encapsulating Security Header. This particular mechanism provides integrity and confidentiality to IPng datagrams. It’s simpler than similar security protocols, such as the Network Layer Security Protocol (ISO NLSP), but it remains flexible and algorithm independent. To ensure this header’s interoperability over the Internet, the Data Encryption Standard (DES) algorithm in the Cipher Block Chaining (CBC) mode (DES CBC) is being used as the standard algorithm. The DES CBC encryption process employs a 64-bit cryptographic key system.
Overall, IPng appears to be a very promising way of minimizing, if not eliminating, a few of the major problems in TCP/IP networking, especially Internet and security problems. You can expect every major vendor on the planet to adopt and implement this new protocol version in its hardware and software.
As you may have gathered, TCP/IP is an ever-evolving family of protocols. With the explosion of the Internet, we are seeing some of the limitations of this protocol suite. One problem in particular is that we will soon run out of usable IP addresses under the current specification, with so many new connections to the Internet being built and installed every day. Another major issue is security. Both of these serious problems are being addressed by various consortia that are quickly finding the answers. Let’s look at one of the foremost proposed solutions because it is likely to become a integral part of the protocol suite in the very near future.
The current version of the IP protocol is version 4, or IPv4, and the next generation, IPv6 or IPng (IP next generation), is set to become formally adopted. IPng was recommended by the IPng Area Directors of the Internet Engineering Task Force (IETF) at the Toronto IETF meeting held on July 25, 1994, as documented in RFC 1752, "The Recommendation for the IP Next Generation Protocol." (Request for Comments (RFCs) are a standard way to propose and debate the merits of any significant change or modification to a standard involving TCP/IP and the Internet in an open forum.) IPng was approved by the Internet Engineering Steering Group and made a Proposed Standard on November 17, 1994. The core set of IPng protocols was made an official IETF Proposed Standard on September 18, 1995.
IPng can be installed as a normal software upgrade to Internet devices and is interoperable with the current version of IPv4 found in today’s TCP/IP protocol. IPng is designed to run well on high performance networks, such as Asynchronous Transfer Mode (ATM), and at the same time is still efficient for low-bandwidth networks, such as wireless networks. In addition, IPng provides a platform for new Internet functions that will be required in the near future.
IPng was designed to be an evolutionary step up from IPv4 but not to be a radical step away from it. Functions that work in IPv4 were kept in the IPng specification, and likewise, the functions that didn’t work were removed. The changes from IPv4 to IPng fall primarily into the following categories:
• Expanded routing and addressing capabilities.
• IPng increases the IP address size from 32 bits to 128 bits, which obviously supports more levels of addressing and a much greater number of addressable nodes. IPng also facilitates a simpler means of automatically configuring IP addresses.
• A new type of address, the anycast address, is defined in IPng. An anycast address identifies nodes; a packet sent to an anycast address is delivered to one of the nodes. Using anycast addresses in the IPng source route lets nodes control the path along which their traffic flows. IPng address types are discussed further later in this section.
• Header format simplification - Some IPv4 header fields have been dropped or made optional to reduce the common processing cost of packet handling and to keep the bandwidth cost of the IPng header as low as possible despite the increased size of the addresses. Even though the IPng addresses are four times longer than the IPv4 addresses, the IPng header is only twice the size of the IPv4 header.
• Improved support for options - Changes in the way IP header options are encoded allow for more efficient forwarding, less stringent limits on the length of options, and greater flexibility for introducing new options.
• Quality-of-service capabilities - A new capability enables the labeling of packets belonging to particular traffic flows for which the sender requests special handling, such as nondefault quality of service or real-time service.
• Authentication and privacy capabilities - IPng defines extensions that provide support for authentication, data integrity, and confidentiality. These definitions are included as a basic element of IPng and will be included in all implementations.
There are three basic types of IPng addresses: unicast, anycast, and multicast. Unicast addresses identify a single interface. Anycast addresses identify a set of interfaces so that a packet sent to an anycast address is delivered to one member of the set. Multicast addresses identify groups of interfaces, so that a packet sent to a multicast address is delivered to all the interfaces in the group. Multicast addresses in IPng supersede broadcast addresses.
IPng supports 128-bit addresses, or four times the number of bits as the IPv4 32-bit addresses. This 128-bit addressing scheme is several times the size of the current IPv4 32-bit address space - 4 billion squared times the current space, or 340,282,366,920,938,463,463,374,607,431,768,211,456 bits.
The Internet has a number of major security problems and lacks effective privacy and authentication mechanisms below the application layer. IPng corrects these shortcomings with two integrated options that provide security services. These two options may be used separately or together to provide different levels of security to different users. This feature is very important because different user communities have different security requirements.
The first security mechanism, the IPng Authentication Header, is an extension header that gives IPng datagrams authentication and integrity without confidentiality. Although the extension is algorithm independent and will support many different authentication techniques, the use of an MD5 security system has been proposed to help ensure this feature’s interoperability within the Internet.
The IPng Authentication Header can eliminate a significant class of network attacks, including host-masquerading attacks. Using the IPng Authentication Header is particularly important when source routing is used with IPng because of the known risks in IP source routing. Its placement at the Internet layer can help provide host origin authentication to those upper-layer protocols and services that currently lack meaningful protection schemes.
The second security extension header provided with IPng is the IPng Encapsulating Security Header. This particular mechanism provides integrity and confidentiality to IPng datagrams. It’s simpler than similar security protocols, such as the Network Layer Security Protocol (ISO NLSP), but it remains flexible and algorithm independent. To ensure this header’s interoperability over the Internet, the Data Encryption Standard (DES) algorithm in the Cipher Block Chaining (CBC) mode (DES CBC) is being used as the standard algorithm. The DES CBC encryption process employs a 64-bit cryptographic key system.
Overall, IPng appears to be a very promising way of minimizing, if not eliminating, a few of the major problems in TCP/IP networking, especially Internet and security problems. You can expect every major vendor on the planet to adopt and implement this new protocol version in its hardware and software.
0 TCP IP STEP 1
IP ADDRESSING EXPLAINED
So far, we have learned how TCP and IP work together to move data across a network. In this section, we cover what IP addresses are and what is needed in conjunction with an IP address to move data. This section helps you understand why IP addresses are so necessary and how they are used on TCP/IP networks.
Ethernet Addresses
Each Ethernet interface or Ethernet network card installed on a network has its own unique hardware address, known as an Ethernet address or media access control (MAC) address.
A MAC address is a 48-bit number that is preprogrammed by the manufacturer of the hardware device. MAC addresses consist of a unique six-part number annotated in hexadecimal; the value of each part ranges from 00 to FF. The first three parts of the MAC address are called the organizationally unique identifier (OUI) and are assigned by the Institute for Electrical and Electronics Engineers (IEEE). OUIs are purchased by Ethernet device manufacturers, who then assign the last three parts of the MAC address, thereby making each address assignment unique. For example, 01:b7:a3:0b:e1:19 is a MAC address, where 01:b7:a3 is the OUI and 0b:e1:19 is the unique number assigned by the manufacturer.
So far, we have learned how TCP and IP work together to move data across a network. In this section, we cover what IP addresses are and what is needed in conjunction with an IP address to move data. This section helps you understand why IP addresses are so necessary and how they are used on TCP/IP networks.
Ethernet Addresses
Each Ethernet interface or Ethernet network card installed on a network has its own unique hardware address, known as an Ethernet address or media access control (MAC) address.
A MAC address is a 48-bit number that is preprogrammed by the manufacturer of the hardware device. MAC addresses consist of a unique six-part number annotated in hexadecimal; the value of each part ranges from 00 to FF. The first three parts of the MAC address are called the organizationally unique identifier (OUI) and are assigned by the Institute for Electrical and Electronics Engineers (IEEE). OUIs are purchased by Ethernet device manufacturers, who then assign the last three parts of the MAC address, thereby making each address assignment unique. For example, 01:b7:a3:0b:e1:19 is a MAC address, where 01:b7:a3 is the OUI and 0b:e1:19 is the unique number assigned by the manufacturer.
0 TCP IP STEP 2 CLASSIFICATIONS
IP Addresses and Classifications
TCP/IP requires each host on a TCP/IP network to have its own unique IP address. An IP address is a 32-bit number, represented by a four-part decimal number (n.n.n.n), with each of the four parts - called octets - representing an 8-bit portion of the whole address number. Each octet can have a value ranging from 1 to 254. IP addresses used on the Internet are assigned and regulated by the Internet Assigned Numbers Authority, who in turn delegates the assignment process to the InterNIC. You should ask your Internet Service Provider for IP addresses when connecting your network to the Internet.
Another term to know is address pools. Address pools are blocks of IP addresses that are commonly referred to as networks. There are five types of address pools: Class A, Class B, Class C, Class D, and Class E. The first octet of the IP address represents the Class A network number; the second octet represents the Class B network number; and the third octet represents the Class C network number. The fourth octet of an IP address represents the actual host number. When you put all the octets together (e.g., 207.91.166.2), you have an IP address. Class D and Class E networks are special networks. They’re defined below, along with A, B, and C networks.
• Class A networks number large networks. The high-order bit of the first octet is always zero, which leaves seven bits in the first octet to define up to 127 networks. The remaining 24 bits of the 32-bit IP address are used to define the hosts, creating the possibility of 16,777,216 unique host addresses.
• Class B networks number medium-sized networks. The first two high-order bits of the first octet are always 10. Class B networks define up to 16,384 networks that can contain as many as 65,535 unique host addresses.
• Class C networks are typically used most often for numbering small networks. The first three bits are always 110, leaving room to define up to 2,097,152 networks, with each network having as many as 254 unique host addresses.
• Class D networks are made up of special multicast addresses that cannot be used for addressing devices on a network. The first four high-order bits are always set to 1110.
• Class E networks are reserved for experiments, with the first four high-order bits set to 1111.
IP Subnets
An IP subnet is a way of breaking a set of addresses, commonly referred to as an IP network, into smaller, more controllable pieces. When IP networks are subnetted, they can be routed independently to different gateways, which uses address space and bandwidth much more efficiently. An IP subnet operates by defining a subnet mask. The subnet mask is very similar in structure to an IP address in that it also has four parts, or octets. However, the allowable values of those octets are not quite the same as those in an IP address.
Subnet masks modify a 32-bit IP address by performing a mathematical calculation of the IP address and subnet mask at the bit level. Subnetting actually modifies the IP address by using the host address bits as additional network address bits.
The most common type of subnetting is performed on an even-byte boundary, although you may subnet a network using a bit boundary as well. An example of a subnet mask for a Class C network using an even-byte boundary is 255.255.255.0. If you use a Class C network address pool of 207.91.166.0, with usable host addresses ranging from 207.91.166.1 through 207.91.166.254, in combination with a subnet mask of 255.255.255.0, then all the addresses in that pool can be routed to the same gateway, and all are considered a part of the same logical IP network.
Subnetting can reduce the size of routing tables, minimize network traffic, isolate networks, maximize performance, and enhance your ability to secure a network. How you implement subnetting depends on many factors related to the use and design of your network.
Multihoming
A host may have more than one IP address; these hosts are known as multihomed hosts. Normally, hosts have just a single IP address; however, multihoming is necessary for several purposes, including establishing virtual Web servers. Multihoming can be useful for routing on a host computer containing more than one network card. Each card has its own unique IP address, and in practice, each of those cards could be connected to different physical network segments. With this type of configuration, more than one route to any given host can exist, which increases the probability of reaching it. This setup is useful when a network link goes down or becomes saturated with traffic.
TCP/IP requires each host on a TCP/IP network to have its own unique IP address. An IP address is a 32-bit number, represented by a four-part decimal number (n.n.n.n), with each of the four parts - called octets - representing an 8-bit portion of the whole address number. Each octet can have a value ranging from 1 to 254. IP addresses used on the Internet are assigned and regulated by the Internet Assigned Numbers Authority, who in turn delegates the assignment process to the InterNIC. You should ask your Internet Service Provider for IP addresses when connecting your network to the Internet.
Another term to know is address pools. Address pools are blocks of IP addresses that are commonly referred to as networks. There are five types of address pools: Class A, Class B, Class C, Class D, and Class E. The first octet of the IP address represents the Class A network number; the second octet represents the Class B network number; and the third octet represents the Class C network number. The fourth octet of an IP address represents the actual host number. When you put all the octets together (e.g., 207.91.166.2), you have an IP address. Class D and Class E networks are special networks. They’re defined below, along with A, B, and C networks.
• Class A networks number large networks. The high-order bit of the first octet is always zero, which leaves seven bits in the first octet to define up to 127 networks. The remaining 24 bits of the 32-bit IP address are used to define the hosts, creating the possibility of 16,777,216 unique host addresses.
• Class B networks number medium-sized networks. The first two high-order bits of the first octet are always 10. Class B networks define up to 16,384 networks that can contain as many as 65,535 unique host addresses.
• Class C networks are typically used most often for numbering small networks. The first three bits are always 110, leaving room to define up to 2,097,152 networks, with each network having as many as 254 unique host addresses.
• Class D networks are made up of special multicast addresses that cannot be used for addressing devices on a network. The first four high-order bits are always set to 1110.
• Class E networks are reserved for experiments, with the first four high-order bits set to 1111.
IP Subnets
An IP subnet is a way of breaking a set of addresses, commonly referred to as an IP network, into smaller, more controllable pieces. When IP networks are subnetted, they can be routed independently to different gateways, which uses address space and bandwidth much more efficiently. An IP subnet operates by defining a subnet mask. The subnet mask is very similar in structure to an IP address in that it also has four parts, or octets. However, the allowable values of those octets are not quite the same as those in an IP address.
Subnet masks modify a 32-bit IP address by performing a mathematical calculation of the IP address and subnet mask at the bit level. Subnetting actually modifies the IP address by using the host address bits as additional network address bits.
The most common type of subnetting is performed on an even-byte boundary, although you may subnet a network using a bit boundary as well. An example of a subnet mask for a Class C network using an even-byte boundary is 255.255.255.0. If you use a Class C network address pool of 207.91.166.0, with usable host addresses ranging from 207.91.166.1 through 207.91.166.254, in combination with a subnet mask of 255.255.255.0, then all the addresses in that pool can be routed to the same gateway, and all are considered a part of the same logical IP network.
Subnetting can reduce the size of routing tables, minimize network traffic, isolate networks, maximize performance, and enhance your ability to secure a network. How you implement subnetting depends on many factors related to the use and design of your network.
Multihoming
A host may have more than one IP address; these hosts are known as multihomed hosts. Normally, hosts have just a single IP address; however, multihoming is necessary for several purposes, including establishing virtual Web servers. Multihoming can be useful for routing on a host computer containing more than one network card. Each card has its own unique IP address, and in practice, each of those cards could be connected to different physical network segments. With this type of configuration, more than one route to any given host can exist, which increases the probability of reaching it. This setup is useful when a network link goes down or becomes saturated with traffic.
0 TCP IP STEP 2
ASPECTS OF TCP/IP
TCP/IP relies on certain functions and configuration settings to operate correctly. In this section, we look at some of the most crucial aspects of the protocol suite and other functions on which it depends. Pay special attention to these items because without an understanding of them, you’re probably going to find yourself either suffering from a big headache or pulling your hair out from frustration.
Gateways and Routing
Routing is the process of getting your data across a network. Routing a datagram is very similar to traveling in your car. Before you drive off to your destination, you must determine which roads you are going to take to get there, and sometimes you have to change your mind along the way, altering your route for any number of possible reasons - a road may be closed, or traffic may be too heavy on a certain highway. TCP/IP routing follows this same concept.
The IP portion of the TCP/IP protocol takes care of identifying the starting point and the destination for your data. If IP doesn’t know the address of the destination for the datagram and can’t find out, it sends the datagram to its gateway. Typically, each host on a TCP/IP network has a gateway - an off-ramp for datagrams that are not destined for the local network. If a datagram is sent to the gateway, the gateway then takes on the job of forwarding the datagram to the remote destination.
TCP/IP relies on certain functions and configuration settings to operate correctly. In this section, we look at some of the most crucial aspects of the protocol suite and other functions on which it depends. Pay special attention to these items because without an understanding of them, you’re probably going to find yourself either suffering from a big headache or pulling your hair out from frustration.
Gateways and Routing
Routing is the process of getting your data across a network. Routing a datagram is very similar to traveling in your car. Before you drive off to your destination, you must determine which roads you are going to take to get there, and sometimes you have to change your mind along the way, altering your route for any number of possible reasons - a road may be closed, or traffic may be too heavy on a certain highway. TCP/IP routing follows this same concept.
The IP portion of the TCP/IP protocol takes care of identifying the starting point and the destination for your data. If IP doesn’t know the address of the destination for the datagram and can’t find out, it sends the datagram to its gateway. Typically, each host on a TCP/IP network has a gateway - an off-ramp for datagrams that are not destined for the local network. If a datagram is sent to the gateway, the gateway then takes on the job of forwarding the datagram to the remote destination.
0 TCP IP STEP 3
Each gateway has a defined set of routing tables that tells it the path to certain destinations. Gateways don’t know where every IP address is, so gateways in turn have their own gateways. When a gateway doesn’t know the way to a particular destination, it forwards the datagram to its own gateway. This cycle of routing is continued until the datagram finally arrives at its destination. The entire path traveled from the origin to the destination is called the route.
Datagrams may travel to a particular destination one way one time and another way another time. The route is determined by many variables that occur along the route. For instance, overloaded gateways processing too much traffic may not respond in a timely manner or may simply refuse to route your traffic, causing a timeout. That timeout causes the sending gateway to seek an alternative route for the datagram. A timeout could also be caused by network links or network devices being down or many other factors.
In most cases, routes can be predefined and made to remain static if need be. Alternative routes can also be predefined, providing a maximum probability that your datagrams will arrive at their final destination. The way routing is handled on your network is purely a matter of preference. You should note that improper routing can lead to poor network performance; network routers may become overburdened with traffic or may inadvertently assign longer routes than necessary.
Hosts, Host Names, and Domain Names
The word host describes various devices on the network. Technically, any device on a network that has some sort of address and is capable of sending and/or receiving data or information can be called a host. A printer can be a host, a network fax machine can be a host, and a computer system can certainly be a host. However, hosts are usually thought of as computer systems on a network. On most networks, hosts have names. On TCP/IP networks, hosts have names that are a subset of domain names.
Datagrams may travel to a particular destination one way one time and another way another time. The route is determined by many variables that occur along the route. For instance, overloaded gateways processing too much traffic may not respond in a timely manner or may simply refuse to route your traffic, causing a timeout. That timeout causes the sending gateway to seek an alternative route for the datagram. A timeout could also be caused by network links or network devices being down or many other factors.
In most cases, routes can be predefined and made to remain static if need be. Alternative routes can also be predefined, providing a maximum probability that your datagrams will arrive at their final destination. The way routing is handled on your network is purely a matter of preference. You should note that improper routing can lead to poor network performance; network routers may become overburdened with traffic or may inadvertently assign longer routes than necessary.
Hosts, Host Names, and Domain Names
The word host describes various devices on the network. Technically, any device on a network that has some sort of address and is capable of sending and/or receiving data or information can be called a host. A printer can be a host, a network fax machine can be a host, and a computer system can certainly be a host. However, hosts are usually thought of as computer systems on a network. On most networks, hosts have names. On TCP/IP networks, hosts have names that are a subset of domain names.
0 TCP IP STEP 3
Internet host names are an easy way to remember a long decimal IP address. A host name is typically the name of a device that has a specific IP address. A host name and a domain name make up a fully qualified domain name. For example, www.ntshop.net is a fully qualified domain name, where www is the host name and ntshop.net is the domain name. Hosts on a network use names the same way people use names. We all have a Social Security number, and we can certainly remember that number if need be, but imagine if all of your friends and associates had to be called by their Social Security numbers instead of regular names! We use words as names instead because they are easier to remember. Likewise, it’s easier to remember www.ntshop.net than it is to remember 207.91.166.2.
Domain Name Service
Domain Name Service, or DNS, cross-references specific information to translate host names and domain names to IP addresses and vice versa using a lookup table that the network administrator defines and configures. For example, when you type www.ntshop.net in your Web browser, the DNS server returns 206.91.166.2 as an answer, allowing the Web browser to locate the server and load the home page.
Although you can run a TCP/IP network without it, DNS is considered an essential part of any TCP/IP network because it makes the task of remembering addresses much easier. Although humans think best in words, computers work best with numbers. DNS lets the human remember the name while DNS remembers the corresponding numbers, much like a phone book.
DNS tables compile records that are defined in a particular structure. Depending on the record type, the structure can be composed of four or five parts, but for the purposes of this book, we’ll focus on the three important parts: the host name, the record type, and the host address pointer.
DNS tables can store several different types of records. The most common record types are address records, mail exchange records, and alias records. Let’s look at address records, commonly eferred to as A records. A records correlate host names to IP addresses. An address record entry for a host named "mail" in the "ntshop.net" domain is shown below.
mail.ntshop.net. IN A 207.91.166.2
The next record type we’ll look at is the mail exchange record. Mail exchange records point to the mail servers for a given domain name and describe where mail for that domain should be sent. It is possible to specify several mail servers in order of preference for a given domain, thereby increasing the probability that mail will arrive at its destination if one of the servers is down or not responding.
Domain Name Service
Domain Name Service, or DNS, cross-references specific information to translate host names and domain names to IP addresses and vice versa using a lookup table that the network administrator defines and configures. For example, when you type www.ntshop.net in your Web browser, the DNS server returns 206.91.166.2 as an answer, allowing the Web browser to locate the server and load the home page.
Although you can run a TCP/IP network without it, DNS is considered an essential part of any TCP/IP network because it makes the task of remembering addresses much easier. Although humans think best in words, computers work best with numbers. DNS lets the human remember the name while DNS remembers the corresponding numbers, much like a phone book.
DNS tables compile records that are defined in a particular structure. Depending on the record type, the structure can be composed of four or five parts, but for the purposes of this book, we’ll focus on the three important parts: the host name, the record type, and the host address pointer.
DNS tables can store several different types of records. The most common record types are address records, mail exchange records, and alias records. Let’s look at address records, commonly eferred to as A records. A records correlate host names to IP addresses. An address record entry for a host named "mail" in the "ntshop.net" domain is shown below.
mail.ntshop.net. IN A 207.91.166.2
The next record type we’ll look at is the mail exchange record. Mail exchange records point to the mail servers for a given domain name and describe where mail for that domain should be sent. It is possible to specify several mail servers in order of preference for a given domain, thereby increasing the probability that mail will arrive at its destination if one of the servers is down or not responding.
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When one mail server tries to send mail to another mail server, it first queries the DNS server for the list of mail servers for that domain. Once that list is obtained, the servers are tried in the order of preference listed - if the first mail server listed does not respond, the second one is tried, and so on. If by chance none of the mail servers responds, the mail is returned to the sender. In the typical set of mail server records below, the MX portion of the entry specifies that the record is a mail exchange record, and the numbers 10, 20, and 30 indicate the order of preference.
yourhost.ntshop.net. IN MX 10 mail.ntshop.net.
yourhost.ntshop.net. IN MX 20 mail2.ntshop.net.
yourhost.ntshop.net. IN MX 30 mail3.ntshop.net.
CNAME records, or canonical name records, are also called alias records. CNAME records allow hosts to have more than one name. For example, you may want your Web server, named www, to run your FTP server as well. You could simply create a CNAME record that creates an alias of "www" for "ftp." CNAME records depend on previously defined address records, so you need to establish an address record for "www" before "ftp" would be usable. Sample CNAME records and their associated address records are shown below.
www.ntshop.net IN A 207.91.166.2
ftp.ntshop.net IN CNAME www.ntshop.net.
When you put all these record types together in a file, you have a DNS table:
mail.domain.com IN A 207.91.166.2
mail2.domain.com IN A 207.91.166.198
www.domain.com IN A 207.91.166.4
ftp.domain.com IN CNAME www.domain.com.
host1.domain.com IN MX 10 mail.domain.com.
host1.domain.com IN MX 20 mail2.domain.com.
You can use other types of DNS records; however, we won’t cover them all in this book. DNS can be a complex subject. You should seek out one of the many books devoted to the subject if you want a complete understanding of its intricacies.
yourhost.ntshop.net. IN MX 10 mail.ntshop.net.
yourhost.ntshop.net. IN MX 20 mail2.ntshop.net.
yourhost.ntshop.net. IN MX 30 mail3.ntshop.net.
CNAME records, or canonical name records, are also called alias records. CNAME records allow hosts to have more than one name. For example, you may want your Web server, named www, to run your FTP server as well. You could simply create a CNAME record that creates an alias of "www" for "ftp." CNAME records depend on previously defined address records, so you need to establish an address record for "www" before "ftp" would be usable. Sample CNAME records and their associated address records are shown below.
www.ntshop.net IN A 207.91.166.2
ftp.ntshop.net IN CNAME www.ntshop.net.
When you put all these record types together in a file, you have a DNS table:
mail.domain.com IN A 207.91.166.2
mail2.domain.com IN A 207.91.166.198
www.domain.com IN A 207.91.166.4
ftp.domain.com IN CNAME www.domain.com.
host1.domain.com IN MX 10 mail.domain.com.
host1.domain.com IN MX 20 mail2.domain.com.
You can use other types of DNS records; however, we won’t cover them all in this book. DNS can be a complex subject. You should seek out one of the many books devoted to the subject if you want a complete understanding of its intricacies.
0 TCP IP STEP 5
Microsoft’s WINS Server
Windows Internet Naming Service (WINS) is an essential part of the Microsoft networking topology. WINS works with TCP/IP to map NetBIOS names to IP addresses. (NetBIOS is a session-layer protocol that manages data exchange and network access on Windows operating systems.) Because TCP/IP cannot operate with NetBIOS directly, it relies on WINS to get the job done.
WINS operates much as DNS does in that it maintains a table of NetBIOS names mapped to their associated IP addresses. The main difference between WINS and DNS is that the WINS server automatically builds and updates its own tables without user intervention, whereas DNS tables must be built and updated manually. Remember, DNS maps TCP/IP host names to IP addresses, and WINS maps NetBIOS host names to IP addresses.
Each time you need to access a network resource on a Windows NT network using TCP/IP, your system needs to know the host name or IP address. WINS lets you continue using the NetBIOS names that you have already become accustomed to.
The WINS server’s IP address is defined when you configure TCP/IP after installing Windows NT, as you will see later in this chapter. When a Windows NT machine running TCP/IP is booted and attached to the network, it uses the WINS address settings in the TCP/IP configuration to communicate with the WINS server. The Windows NT machine then gives the WINS server various bits of information about itself so that the WINS server may include that information in its dynamic tables. WINS periodically refreshes this information so that its table remains current and accurate.
Windows Internet Naming Service (WINS) is an essential part of the Microsoft networking topology. WINS works with TCP/IP to map NetBIOS names to IP addresses. (NetBIOS is a session-layer protocol that manages data exchange and network access on Windows operating systems.) Because TCP/IP cannot operate with NetBIOS directly, it relies on WINS to get the job done.
WINS operates much as DNS does in that it maintains a table of NetBIOS names mapped to their associated IP addresses. The main difference between WINS and DNS is that the WINS server automatically builds and updates its own tables without user intervention, whereas DNS tables must be built and updated manually. Remember, DNS maps TCP/IP host names to IP addresses, and WINS maps NetBIOS host names to IP addresses.
Each time you need to access a network resource on a Windows NT network using TCP/IP, your system needs to know the host name or IP address. WINS lets you continue using the NetBIOS names that you have already become accustomed to.
The WINS server’s IP address is defined when you configure TCP/IP after installing Windows NT, as you will see later in this chapter. When a Windows NT machine running TCP/IP is booted and attached to the network, it uses the WINS address settings in the TCP/IP configuration to communicate with the WINS server. The Windows NT machine then gives the WINS server various bits of information about itself so that the WINS server may include that information in its dynamic tables. WINS periodically refreshes this information so that its table remains current and accurate.
0 TCP IP STEP 6
With the release of Windows NT 4.0, Microsoft included its own DNS server, which is designed to interoperate with the WINS server. Microsoft’s DNS server includes a new DNS record type, the WINS record. This record, when defined, tells a DNS server to query the WINS server for host IP address information. In effect, this feature lets the DNS server look up the IP address of a host name that may not be in the DNS tables.
One real advantage to this setup becomes apparent when you use Dynamic Host Configuration Protocol (DHCP) to dynamically assign IP addresses to machines on your network. You may recall that DNS requires static IP addresses to be defined for each host and that DNS has no way of knowing when that address changes. With WINS at its side, a Microsoft DNS server can automatically keep up with the ever-changing IP addresses by simply relying on WINS to track them automatically. Then, when DNS needs to know an IP address, it can ask the WINS server.
You can certainly use WINS and DNS on your network, or you could use one without the other. Your choice should be based on whether your network is connected to the Internet and whether you use DHCP. If you use DHCP and are connected to the Internet, you’re probably going to find that things work best with both WINS and DNS installed.
One real advantage to this setup becomes apparent when you use Dynamic Host Configuration Protocol (DHCP) to dynamically assign IP addresses to machines on your network. You may recall that DNS requires static IP addresses to be defined for each host and that DNS has no way of knowing when that address changes. With WINS at its side, a Microsoft DNS server can automatically keep up with the ever-changing IP addresses by simply relying on WINS to track them automatically. Then, when DNS needs to know an IP address, it can ask the WINS server.
You can certainly use WINS and DNS on your network, or you could use one without the other. Your choice should be based on whether your network is connected to the Internet and whether you use DHCP. If you use DHCP and are connected to the Internet, you’re probably going to find that things work best with both WINS and DNS installed.
0 TCP IP STEP 7
INSTALLING TCP/IP ON WINDOWS NT
Now that we have a basic understanding of TCP/IP and how it works on a network, let’s walk through installing and configuring TCP/IP on Windows NT Server 4.0. In this section, we work with these basic assumptions:
• you are using an Internet domain name of "company.com"
• your server’s TCP/IP host name is "www"
• your server’s IP address is 204.176.47.2
• your server has a subnet mask of 255.255.255.0
• this particular server has only one network card installed
• you have a WINS server installed and running with an IP address of 204.176.47.1
Follow these steps to install TCP/IP.
Open the Control Panel by clicking Start, choosing Settings, and clicking Control Panel. A window containing all the installed Control Panel applets will appear.
Once the Control Panel is active, scroll down until you locate the Network and double-click on it to bring up the Network Configuration dialog box Select the Protocols tab and click Add.
The Select Network Protocol dialog box will appear). Scroll down the list of available protocols until you see TCP/IP Protocol. Double-click TCP/IP Protocol or click the protocol and click OK to add it to your network configuration.
Now that we have a basic understanding of TCP/IP and how it works on a network, let’s walk through installing and configuring TCP/IP on Windows NT Server 4.0. In this section, we work with these basic assumptions:
• you are using an Internet domain name of "company.com"
• your server’s TCP/IP host name is "www"
• your server’s IP address is 204.176.47.2
• your server has a subnet mask of 255.255.255.0
• this particular server has only one network card installed
• you have a WINS server installed and running with an IP address of 204.176.47.1
Follow these steps to install TCP/IP.
Open the Control Panel by clicking Start, choosing Settings, and clicking Control Panel. A window containing all the installed Control Panel applets will appear.
Once the Control Panel is active, scroll down until you locate the Network and double-click on it to bring up the Network Configuration dialog box Select the Protocols tab and click Add.
The Select Network Protocol dialog box will appear). Scroll down the list of available protocols until you see TCP/IP Protocol. Double-click TCP/IP Protocol or click the protocol and click OK to add it to your network configuration.
0 TCP IP STEP 8
The Select Network Protocol dialog box will appear). Scroll down the list of available protocols until you see TCP/IP Protocol. Double-click TCP/IP Protocol or click the protocol and click OK to add it to your network configuration.
You may be shown a dialog box like that in, asking whether you have a DHCP Server on your network and if you want to use it for dynamic IP address assignment. In most cases, you’ll want your server to have a static IP address, so click No even if you have a DHCP server on your network.
Next, the Network Protocol dialog box asks where it can find the Windows NT installation files it needs to complete the TCP/IP setup. They should be in the same place you installed your Windows NT from, usually your CD-ROM drive. Insert your CD-ROM, enter the drive letter in the dialog box as shown in and click Continue. TCP/IP Setup copies the necessary files to your hard drive and closes the dialog box to continue the setup procedure.
Now that all the necessary files have been copied, you need to set the properties of the TCP/IP drivers. Windows NT TCP/IP setup will continue by rebuilding the registry entries and bindings for the network. It will detect that TCP/IP has not been configured and bring up the TCP/IP Properties dialog box
The first tab is the IP Address tab. Make sure your network card is displayed in the Adapter list. Next, select Specify IP Address and fill in the IP Address, Subnet Mask, and Default Gateway fields. The Advanced button presents a dialog box that lets you add more IP addresses and gateways and manage some aspects of TCP/IP security. Because we assume that this host has only one gateway and one IP address, we won’t go into the Advanced dialog box at this time, but we cover the TCP/IP security settings later in this book.
Click the DNS tab to display the DNS properties First, type www, which is the host name. Now fill in the Domain field with your domain name or your ISP’s domain name; remember, we’re using "company.com" for this example. Now click Add under the DNS Service Search Order list box. You will see a dialog box where you enter an IP address of your first DNS server. After you have entered the first DNS server’s IP address, click OK, then click Add again to add your second DNS server’s IP address, if you have one. Windows NT lets you specify up to three DNS server addresses.
The Domain Suffix Search Order provides a list of domain names to search when you specify only a host name. Suppose you want to ping a host named mail.ntshop.net (ping sends a test packet to a host and waits for a response indicating that the packet arrived successfully). Open a DOS console window, type the command ping mail, and the TCP/IP protocol automatically appends your default domain name to the end, making it mail.ntshop.net, where mail is called the prefix, and ntshop.net is the suffix. Adding domain names to this list allows other domains to be searched automatically for a host with this same name. This feature can be very useful on some networks; however, for this installation example, we’ll leave this list blank.
Click the WINS Address tab to display the WINS Address properties, as shown in. Type the IP address of your WINS server in the Primary WINS server box. If your network has more than one WINS server, type the IP address of your secondary WINS server in the
You may be shown a dialog box like that in, asking whether you have a DHCP Server on your network and if you want to use it for dynamic IP address assignment. In most cases, you’ll want your server to have a static IP address, so click No even if you have a DHCP server on your network.
Next, the Network Protocol dialog box asks where it can find the Windows NT installation files it needs to complete the TCP/IP setup. They should be in the same place you installed your Windows NT from, usually your CD-ROM drive. Insert your CD-ROM, enter the drive letter in the dialog box as shown in and click Continue. TCP/IP Setup copies the necessary files to your hard drive and closes the dialog box to continue the setup procedure.
Now that all the necessary files have been copied, you need to set the properties of the TCP/IP drivers. Windows NT TCP/IP setup will continue by rebuilding the registry entries and bindings for the network. It will detect that TCP/IP has not been configured and bring up the TCP/IP Properties dialog box
The first tab is the IP Address tab. Make sure your network card is displayed in the Adapter list. Next, select Specify IP Address and fill in the IP Address, Subnet Mask, and Default Gateway fields. The Advanced button presents a dialog box that lets you add more IP addresses and gateways and manage some aspects of TCP/IP security. Because we assume that this host has only one gateway and one IP address, we won’t go into the Advanced dialog box at this time, but we cover the TCP/IP security settings later in this book.
Click the DNS tab to display the DNS properties First, type www, which is the host name. Now fill in the Domain field with your domain name or your ISP’s domain name; remember, we’re using "company.com" for this example. Now click Add under the DNS Service Search Order list box. You will see a dialog box where you enter an IP address of your first DNS server. After you have entered the first DNS server’s IP address, click OK, then click Add again to add your second DNS server’s IP address, if you have one. Windows NT lets you specify up to three DNS server addresses.
The Domain Suffix Search Order provides a list of domain names to search when you specify only a host name. Suppose you want to ping a host named mail.ntshop.net (ping sends a test packet to a host and waits for a response indicating that the packet arrived successfully). Open a DOS console window, type the command ping mail, and the TCP/IP protocol automatically appends your default domain name to the end, making it mail.ntshop.net, where mail is called the prefix, and ntshop.net is the suffix. Adding domain names to this list allows other domains to be searched automatically for a host with this same name. This feature can be very useful on some networks; however, for this installation example, we’ll leave this list blank.
Click the WINS Address tab to display the WINS Address properties, as shown in. Type the IP address of your WINS server in the Primary WINS server box. If your network has more than one WINS server, type the IP address of your secondary WINS server in the
0 TCP IP STEP NO 9
Secondary WINS server box. We want Windows NT to use DNS to look up TCP/IP host names and addresses, so select the checkbox beside Enable DNS for Windows Resolution. By default, the Enable LMHOSTS Lookup checkbox is selected. In this example installation, we want to rely only on DNS for lookups, so clear this box. LMHOSTS Lookup is a method of name resolution that uses a text file similar to DNS tables. However, it differs from DNS in that it maps IP addresses to NetBIOS computer names, similar to the WINS server, except that the table must be updated manually.
All computers on a TCP/IP network must use the same scope ID. Ask your network administrator whether a scope is defined for your network and type the scope ID in this field. If you don’t have a scope on your network, simply leave this field blank. Most Windows NT networks don’t use a Scope ID.
Next, click the DHCP Relay. DHCP lets workstations and servers be assigned IP addresses automatically. The primary reason for using DHCP is that it can provide a centralized method of managing IP addresses. We won’t delve into all the details of DHCP in this book, and for example purposes, we’ll assume that you are not using a DHCP server on your network, so no changes are necessary.
Now click the Routing tab to display the routing properties The Routing dialog box has a single checkbox labeled Enable IP Forwarding. IP forwarding allows datagrams to be forwarded on a multihomed host. A multihomed host has more than one network card installed or more than one IP address assigned to a network card. With multihomed hosts, sometimes datagrams need to be routed between the network cards to other parts or segments of the network. This setting is a key factor in establishing a secure network segment and is covered later in this book. For now, do not select the check box.
Now that you’ve completed configuring the TCP/IP properties, click OK to finish the setup process. The Binding Review is completed, and a dialog box asking whether you want to reboot now appears. It is always best to reboot whenever Windows NT asks you, so click Yes. Windows NT will write your settings to the registry and reboot. The registry can be viewed and modified with Regedt32.exe, which we cover later in this book.
After the server has rebooted, you can log on and test the configuration using the Ping utility. Open a DOS console window by clicking Start, selecting Programs, and choosing MS-DOS. When the DOS window opens, type the following command: ping 127.0.0.1. You should see a response similar to the one shown in
Ping sends a diagnostic packet to the address specified and waits for a response for a predetermined amount of time. We use the address 127.0.0.1 in this instance because it is a special loopback address designed for testing. If Ping does not receive a response in the predetermined amount of time, a time-out error is reported, as shown in
After you have pinged the localhost address, you should try to ping another host on your network to make sure everything is working correctly. For example, if you have another host on your network with the IP address 207.91.166.199, you can ping that address, as shown . You may also want to test your DNS or WINS setup at this time as well. You can
All computers on a TCP/IP network must use the same scope ID. Ask your network administrator whether a scope is defined for your network and type the scope ID in this field. If you don’t have a scope on your network, simply leave this field blank. Most Windows NT networks don’t use a Scope ID.
Next, click the DHCP Relay. DHCP lets workstations and servers be assigned IP addresses automatically. The primary reason for using DHCP is that it can provide a centralized method of managing IP addresses. We won’t delve into all the details of DHCP in this book, and for example purposes, we’ll assume that you are not using a DHCP server on your network, so no changes are necessary.
Now click the Routing tab to display the routing properties The Routing dialog box has a single checkbox labeled Enable IP Forwarding. IP forwarding allows datagrams to be forwarded on a multihomed host. A multihomed host has more than one network card installed or more than one IP address assigned to a network card. With multihomed hosts, sometimes datagrams need to be routed between the network cards to other parts or segments of the network. This setting is a key factor in establishing a secure network segment and is covered later in this book. For now, do not select the check box.
Now that you’ve completed configuring the TCP/IP properties, click OK to finish the setup process. The Binding Review is completed, and a dialog box asking whether you want to reboot now appears. It is always best to reboot whenever Windows NT asks you, so click Yes. Windows NT will write your settings to the registry and reboot. The registry can be viewed and modified with Regedt32.exe, which we cover later in this book.
After the server has rebooted, you can log on and test the configuration using the Ping utility. Open a DOS console window by clicking Start, selecting Programs, and choosing MS-DOS. When the DOS window opens, type the following command: ping 127.0.0.1. You should see a response similar to the one shown in
Ping sends a diagnostic packet to the address specified and waits for a response for a predetermined amount of time. We use the address 127.0.0.1 in this instance because it is a special loopback address designed for testing. If Ping does not receive a response in the predetermined amount of time, a time-out error is reported, as shown in
After you have pinged the localhost address, you should try to ping another host on your network to make sure everything is working correctly. For example, if you have another host on your network with the IP address 207.91.166.199, you can ping that address, as shown . You may also want to test your DNS or WINS setup at this time as well. You can
0 TCP IP INFORMATION WITH STEP 10
do so by pinging a host by name that has a DNS entry or WINS server configured.
Also, if your network is already attached to the Internet, you can test your gateway by pinging a host that you know is somewhere on the Internet. For example, you could try pinging the Windows NT Magazine Web server by typing ping www.winntmag.com. You should always get a response similar to the one shown in except that the response times might be a bit longer, because your packets have to travel across the Internet and back.
Now that you have installed TCP/IP on your Windows NT machine, I’ll remind you that you have made an excellent choice for a networking protocol. TCP/IP is absolutely the most performance-oriented protocol you can use, and when it comes to connecting to the Internet, there is simply no other choice.
SUMMARY
Now that we have a basic understanding of TCP/IP and how it works, it should be clear that TCP/IP has many advantages. When you use TCP/IP on an intranet with Windows NT, you gain one distinct advantage over using TCP/IP with other types of network operating systems: ease of configuration and use. You should also understand that literally hundreds of vendors are creating software for the Windows NT operating system, which obviously increases the likelihood of finding software that does what you need.
Another major advantage of using TCP/IP and Windows NT on your intranet is the cross-platform connectivity. TCP/IP is available for almost every operating system in production today. Because TCP/IP is a standard family of protocols, connecting dissimilar operating systems is a breeze. You can connect new systems to older legacy systems in a snap. For example, if your network is composed of Apple Macintosh systems, minicomputers, mainframes, Unix systems, IBM PCs running Novell, and IBM PC-compatible systems running some version of Windows, the components normally would not be able to communicate with each other at all. But with TCP/IP installed on each of them, they are all capable of communicating and transferring data back and forth with ease. This flexibility is not possible with any other networking protocol today.
TCP/IP is the revolution that the computer industry has needed for a long time; however, it has taken the vast popularity of the Internet to institute its wide-spread implementation. Here are some of the major benefits of using TCP/IP:
• TCP/IP is a routable protocol with the ability to send datagrams using a very specific route, which in turn reduces traffic on other parts of a network.
• TCP/IP has a lower overhead than other protocols, which allows much larger networks to be constructed.
• TCP/IP is reliable and has efficient data delivery mechanisms.
• TCP/IP is standardized for cross-platform implementation, making TCP/IP able to send data between computer systems running completely different operating systems, from PCs to mainframes and almost everything in between.
• TCP/IP provides a common addressing scheme across all operating system platforms.
• TCP/IP can run over a variety of network types including Ethernet, Token Ring, X.25, Frame Relay, and even dialup lines.
Also, if your network is already attached to the Internet, you can test your gateway by pinging a host that you know is somewhere on the Internet. For example, you could try pinging the Windows NT Magazine Web server by typing ping www.winntmag.com. You should always get a response similar to the one shown in except that the response times might be a bit longer, because your packets have to travel across the Internet and back.
Now that you have installed TCP/IP on your Windows NT machine, I’ll remind you that you have made an excellent choice for a networking protocol. TCP/IP is absolutely the most performance-oriented protocol you can use, and when it comes to connecting to the Internet, there is simply no other choice.
SUMMARY
Now that we have a basic understanding of TCP/IP and how it works, it should be clear that TCP/IP has many advantages. When you use TCP/IP on an intranet with Windows NT, you gain one distinct advantage over using TCP/IP with other types of network operating systems: ease of configuration and use. You should also understand that literally hundreds of vendors are creating software for the Windows NT operating system, which obviously increases the likelihood of finding software that does what you need.
Another major advantage of using TCP/IP and Windows NT on your intranet is the cross-platform connectivity. TCP/IP is available for almost every operating system in production today. Because TCP/IP is a standard family of protocols, connecting dissimilar operating systems is a breeze. You can connect new systems to older legacy systems in a snap. For example, if your network is composed of Apple Macintosh systems, minicomputers, mainframes, Unix systems, IBM PCs running Novell, and IBM PC-compatible systems running some version of Windows, the components normally would not be able to communicate with each other at all. But with TCP/IP installed on each of them, they are all capable of communicating and transferring data back and forth with ease. This flexibility is not possible with any other networking protocol today.
TCP/IP is the revolution that the computer industry has needed for a long time; however, it has taken the vast popularity of the Internet to institute its wide-spread implementation. Here are some of the major benefits of using TCP/IP:
• TCP/IP is a routable protocol with the ability to send datagrams using a very specific route, which in turn reduces traffic on other parts of a network.
• TCP/IP has a lower overhead than other protocols, which allows much larger networks to be constructed.
• TCP/IP is reliable and has efficient data delivery mechanisms.
• TCP/IP is standardized for cross-platform implementation, making TCP/IP able to send data between computer systems running completely different operating systems, from PCs to mainframes and almost everything in between.
• TCP/IP provides a common addressing scheme across all operating system platforms.
• TCP/IP can run over a variety of network types including Ethernet, Token Ring, X.25, Frame Relay, and even dialup lines.
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