Tài liệu TCP/IP Network Administration- P5 docx

[Chapter 4] 4.7 netconfig 172.16.12.2 Enter gateway address: 172.16.12.1 Enter netmask: 255.255.255.0 Will you access a nameserver: Yes Name Server: 172.16.12.1 ## This completes your network setup. ## ## Hold on to the remaining information for future reference.## Broadcast address: 172.16.12.255 Mail server: 172.16.12.1 Mail relay: 172.16.12.1 Print server: 172.16.12.3 NFS server: 172.16.1.2 Previous: 4.6 Informing the Users TCP/IP Network Administration Next: 4.8 Summary 4.6 Informing the Users Book Index 4.8 Summary [ Library Home | DNS & BIND | TCP/IP | sendmail | sendmail Reference | Firewalls | Practical Security ] file:///C|/mynapster/Downloads/warez/tcpip/ch04_07.htm (2 of 2) [2001-10-15 09:17:57] Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. [Chapter 4] 4.6 Informing the Users Previous: 4.5 Other Services Chapter 4 Getting Started Next: 4.7 netconfig 4.6 Informing the Users All of the configuration information that you gather or develop through the planning process must be given to the users so that they can configure their systems. You can distribute information with several techniques. In Chapter 3 we discussed NIS, NFS, and configuration servers. All of these play a role in informing the user and in simplifying the configuration process. NIS supports several system administration databases that provide many of the basic configuration values. NFS can distribute pre-configured system files to client systems. Configuration servers, such as BOOTP and DHCP, offer every parameter needed to configure a TCP/IP system directly to the client. All of these are important, but they are not the complete solution. The servers require that the client is configured to be a client. For NIS and NFS, the client must have a full basic configuration. Even BOOTP and DHCP require that the user know whether BOOTP or DHCP is being used so that he does not enter any incorrect values during the initial system installation. Therefore, the network administrator must directly communicate with the administrator of the end system, usually through written documentation. 4.6.1 Sample Planning Sheets To communicate this information, the network administrator will often create an installation planning sheet - a short list of information for the system administrator. A sample planning sheet for the workstation peanut, based on some of the topics we have discussed, provides basic configuration details. The planning sheet lists the name, address, subnet mask, the fact that DNS is used, and the fact that RIP is used on subnet 172.16.12.0: Hostname: peanut IP address: 172.16.12.2 Subnet mask: file:///C|/mynapster/Downloads/warez/tcpip/ch04_06.htm (1 of 4) [2001-10-15 09:17:58] Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. [Chapter 4] 4.6 Informing the Users 255.255.255.0 Default gateway: 172.16.12.1 (almond.nuts.com) Broadcast address: 172.16.12.255 Domain name: nuts.com Name servers: 172.16.12.1 (almond.nuts.com) 172.16.6.8 (pack.plant.nuts.com) Routing protocol: Routing Information Protocol (RIP) Mail server: 172.16.12.1 (almond.nuts.com) Mail relay: 172.16.12.1 (almond.nuts.com) Print server: 172.16.12.3 (pecan.nuts.com) NFS server: 172.16.1.2 (filbert.nuts.com) A similar sheet prepared for almond (see below) varies slightly from the planning sheet for peanut. The names and address are different, of course, but the real differences are caused by the fact that almond is a gateway. As a gateway, almond has more than one network interface, and each interface requires its own configuration. Each interface has its own address and can have its own name, subnet mask, and routing protocol. Hostname: almond (172.16.12.1) mil-gw (10.104.0.19) IP address: file:///C|/mynapster/Downloads/warez/tcpip/ch04_06.htm (2 of 4) [2001-10-15 09:17:58] Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. [Chapter 4] 4.6 Informing the Users 172.16.12.1 10.104.0.19 Subnet mask: 255.255.255.0 (172.16.12.1) default (10.104.0.19) Default gateway: none Broadcast address: 172.16.12.255 (172.16.12.1) default (10.104.0.19) Domain name: nuts.com Name servers: 172.16.12.1 (almond.nuts.com) 172.16.6.8 (pack.plant.nuts.com) Routing protocol: Routing Information Protocol (RIP) (172.16.12.1) Border Gateway Protocol (BGP) (10.104.0.19) Print server: 172.16.12.3 (pecan.nuts.com) NFS server: 172.16.1.2 (filbert.nuts.com) We use the information from these planning sheets to configure the systems in subsequent chapters. You may, however, want to format your planning sheets differently. In this book we configure the system directly. We use the configuration commands ourselves so that we can understand and master them. In reality many basic configuration tasks are performed by a network configuration script during the initial operating system installation. You may want to format your planning sheet to be compatible with the prompts of that script. One such script is netconfig, which is used on Linux systems. file:///C|/mynapster/Downloads/warez/tcpip/ch04_06.htm (3 of 4) [2001-10-15 09:17:58] Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. [Chapter 4] 4.6 Informing the Users Previous: 4.5 Other Services TCP/IP Network Administration Next: 4.7 netconfig 4.5 Other Services Book Index 4.7 netconfig [ Library Home | DNS & BIND | TCP/IP | sendmail | sendmail Reference | Firewalls | Practical Security ] file:///C|/mynapster/Downloads/warez/tcpip/ch04_06.htm (4 of 4) [2001-10-15 09:17:58] Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. [Chapter 4] 4.5 Other Services Previous: 4.4 Planning Naming Service Chapter 4 Getting Started Next: 4.6 Informing the Users 4.5 Other Services Three services that are used on many networks are file servers, print servers, and mail servers. The purpose of these services and the protocols they are built on is discussed in Chapter 3. In this section we investigate what information must be passed to the users so that the client systems can be successfully configured, and how the network administrator determines that information. 4.5.1 File servers At a minimum the user needs to know the hostnames of the network file servers. Using the names and the showmount command, the user can determine what filesystems are being offer by the servers and who is permitted to use those filesystems. [8] Without at least the hostname, the user would have to guess which system offered file service. [8] See the showmount command in Chapter 9. A better approach is to give users information that also includes what filesystems are being offered and who should use those filesystems. For example, if the UNIX man pages are made available from a central server, the users should be informed not to install the man pages on their local disk drives and they should be told exactly how to access the centrally supported files. 4.5.2 Print servers Whether printers are shared using lp, lpd, or NFS, the basic information needed to configure the print server's clients is the same: the hostname and IP address of the print server, and the name of the printer. Printer security may also require that the user be given a username and password to access the printer. This is the only information needed to configure the client. However, you probably will want to provide your users with additional information about the features, location and administration of shared printers. 4.5.3 Planning Your Mail System file:///C|/mynapster/Downloads/warez/tcpip/ch04_05.htm (1 of 3) [2001-10-15 09:17:58] Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. [Chapter 4] 4.5 Other Services TCP/IP provides the tools you need to create a reliable, flexible electronic mail system. Servers are one of the tools that improve reliability. It is possible to create a peer-to-peer email network in which every end system directly sends and receives its own mail. However, relying on every system to deliver and collect the mail requires that every system be properly administered and consistently up and running. This isn't practical, because many small systems are offline for large portions of the day. Most networks use servers so that only a few systems need to be properly configured and operational for the mail to go through. The terminology that describes email servers is confusing because all of the server functions usually occur in one computer, and all of the terms are used interchangeably to refer to that system. In this text we differentiate between these functions, but we expect you will do all of these tasks on one UNIX system running sendmail. We use these terms in the following manner: Mail server The mail server collects incoming mail for other computers on the network. It supports interactive logins as well as POP or IMAP so that users can read their mail as they see fit. Mail relay A mail relay is a host that forwards mail between internal systems and from internal systems to remote hosts. Mail relays allow internal systems to have simple mail configurations because only the relay host needs to have software to handle special mail addressing schemes and aliases. Mail gateway A mail gateway is a system that forwards email between dissimilar systems. You don't need a gateway to go from one Internet host to another because both systems use SMTP. You do need a gateway to go from SMTP to X.400 or to a proprietary mailer. In a pure TCP/IP network, this function is not needed. The mail server is the most important component of a reliable system because it eliminates reliance on the user's system. A centrally controlled, professionally operated server collects the mail regardless of whether or not the end system is operational. The relay host also contributes to the reliability of the email system. If mail cannot be immediately delivered by the relay host, it is queued and processed later. An end system also queues mail, but if it is shut down no attempts can be made to deliver queued mail until the system is back online. The mail server and the mail relay are operated 24 hours a day. The design of most TCP/IP email networks is based on the following guidelines: ● Use a mail server to collect mail, and POP or IMAP to deliver the mail. ● Use a mail relay host to forward mail. Implement a simplified email address scheme on the relay host. file:///C|/mynapster/Downloads/warez/tcpip/ch04_05.htm (2 of 3) [2001-10-15 09:17:58] Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. [Chapter 4] 4.5 Other Services ● Standardize on TCP/IP and SMTP. Users who insist on using a proprietary email system should be responsible for obtaining and configuring an SMTP mail gateway for that system in order to connect to your TCP/IP email network. ● Standardize on MIME for binary attachments. Avoid proprietary attachment schemes; they just cause confusion when the users of Brand X email cannot read attachments received from Brand Y. For their client configurations, provide the users with the hostname and IP address of the mail server and the mail relay. The mail server will also require a username and password for each person. Previous: 4.4 Planning Naming Service TCP/IP Network Administration Next: 4.6 Informing the Users 4.4 Planning Naming Service Book Index 4.6 Informing the Users [ Library Home | DNS & BIND | TCP/IP | sendmail | sendmail Reference | Firewalls | Practical Security ] file:///C|/mynapster/Downloads/warez/tcpip/ch04_05.htm (3 of 3) [2001-10-15 09:17:58] Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/ch04_04.htm Previous: 4.3 Planning Routing Chapter 4 Getting Started Next: 4.5 Other Services 4.4 Planning Naming Service To make your network user-friendly, you need to provide a service to convert hostnames into IP addresses. Domain name service (DNS) and the host table, explained in Chapter 3, perform this function. You should plan to use both. To configure her computer, a network user needs to know the domain name, her system's hostname, and the hostname and address of at least one name server. The network administrator provides this information. 4.4.1 Obtaining a Domain Name The first item you need for domain name service is a domain name. You can obtain an official domain name from the InterNIC. Your ISP may be willing to do this for you or to assign you a name within its domain; however, it is likely that you will have to apply for a domain name yourself. You can download the application from ftp://rs.internic.net/templates/domain-template.txt. Pre-select a domain name and have your primary domain name server up and running before you attempt to register the domain name. Use whois as described in Chapter 13, Internet Information Resources , to see if the name you want is in use. Double-check with nslookup as described in Chapter 8, Configuring DNS Name Service . When you are reasonably sure the domain name is still available, start your primary name server running. If you don't want to run your own server, ask your ISP if they offer this service. If they don't, you must either find a new ISP that does, or run the service yourself. Having the primary server up and running doesn't mean that your entire domain must be fully operational, but it does mean that a server must be running to respond to basic queries. When asked, the server should answer that it is the name server for your domain. Configure the primary server as described in Chapter 8. Test it with nslookup. Once you are sure that it at least answers queries about itself, register the domain name. Submit the domain name application form via email to hostmaster@internic.net with a subject line containing the words "NEW DOMAIN" followed by the name of your domain. For example, assuming the completed template is stored in the file domain.application on a Solaris system, the file:///C|/mynapster/Downloads/warez/tcpip/ch04_04.htm (1 of 4) [2001-10-15 09:17:59] Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/ch04_04.htm following command might be used to mail it to the InterNIC for a domain named nuts.com: % Mail hostmaster@internic.net Subject: NEW DOMAIN nuts.com ~r domain.application "domain.application" 49/2732 ^D EOT In response to your email, you receive a reply that contains a tracking number that you use to monitor the status of your domain registration. Use the domain name registration form to change or delete your existing domain name registration. Just fill in the form with the corrected information and mail it to hostmaster@internic.net with a subject line that contains either "MODIFY DOMAIN" or "REMOVE DOMAIN", as appropriate, followed by your domain name. In the very first field of the application form, item 0, ask for the type of registration action: either New ("N"), Modify ("M"), or Delete ("D"). Make sure the letter in this field matches the action indicated on the subject line when you mail in the application. You're required to use email to submit the domain name application. The logic behind this is that if you don't have at least email access to the Internet, you don't need an Internet domain name. This helps reduce the number of frivolous domain name requests, and it automates part of the registration, further reducing the burden of handling domain name requests. Another thing that dramatically reduces the number of frivolous domain name applications is the $100 registration fee. The registration service charges each domain $50 a year to be maintained in the registry. The initial $100 fee covers the first two years. Question 9 asks if the InterNIC should send the bill for the registration fee to you via email or postal mail. Answer with an "E" or a "P". If your "bean counters" will accept an email bill, go that way. You'll get everything finished more quickly. The application form is largely self-explanatory, but a few items require some thought. Two things may be confusing - handles and servers. One is the request for a NIC handle. You have a NIC handle only if you are registered in the NIC white pages. The white pages (discussed in Chapter 12) is a directory of information about users, networks, hosts, and domains. A NIC handle is a record identifier for this directory. A personal NIC handle for a user entry is composed of the user's initials and perhaps a number. For example, my initials are cwh and my NIC handle is cwh3. It is unlikely that you will have a handle unless you have contacted the NIC before. If you don't have a handle, just leave it blank. The NIC will assign you one. You're also asked for the names and addresses of your primary and secondary name servers. The servers listed must be operational and connected to the Internet. [7] Provide the full domain name of the primary server in response to question 7a; e.g. almond.nuts.com. The primary server is usually a name server located at your site, but not always. It isn't necessary to provide your own primary server; and if you aren't directly connected to the Internet, you can't. Even though you are not connected, you may still want to register your domain name with the NIC if you have email access to the Internet. file:///C|/mynapster/Downloads/warez/tcpip/ch04_04.htm (2 of 4) [2001-10-15 09:17:59] Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. [...]... Internet networks is limited An example of a non-connected network is a TCP/IP network that attaches to the outside world via a mail gateway at America Online (AOL) Users on the network can send mail to Internet hosts but they cannot directly rlogin to one of them [1] [1] rlogin is covered in Chapter 9, Configuring Network Servers Many TCP/IP networks are not connected to the Internet On these networks, TCP/IP. .. plan routing If you have: A network with no gateways to other TCP/IP networks No special routing configuration is required in this case The gateways referred to in this discussion are IP routers that interconnect TCP/IP networks If you are not interconnecting TCP/IP networks, you do not need an IP router Neither a default gateway nor a routing protocol needs to be specified A network with a single gateway... Summary Previous: 3.7 File and Print Servers Chapter 3 Network Services Next: 4 Getting Started 3.8 Summary TCP/IP provides some network services that simplify network installation, configuration, and use Name service is one such service and it is used on every TCP/IP network Name service can be provided by the host table, Domain Name Service (DNS), and Network Information Service (NIS) The host table is... architecture, protocols, and services of a TCP/IP network In the next chapter we begin to look at how to install a TCP/IP network by examining the process of planning an installation Previous: 3.7 File and Print Servers 3.7 File and Print Servers TCP/IP Network Administration Book Index Next: 4 Getting Started 4 Getting Started [ Library Home | DNS & BIND | TCP/IP | sendmail | sendmail Reference | Firewalls... answers from your network administrator before putting the system online The network administrator is responsible for making and communicating decisions about overall network configuration If you have an established TCP/IP network, you can skip several sections in this chapter, but you may still want to read about selecting hostnames, planning mail systems, and other topics that affect mature networks as... Connected and Non-Connected Networks First, you must decide whether or not your new network will be directly connected to the Internet The Internet's administration makes a distinction between networks connected to the Internet and those that are not connected A connected network is directly attached to the Internet and has full access to other networks on the Internet A non-connected network is not directly... Name service is the most basic network service, and it is one service that you will certainly run on your network There are, however, other services that you should also include in your network planning process Previous: 4.3 Planning Routing 4.3 Planning Routing TCP/IP Network Administration Book Index Next: 4.5 Other Services 4.5 Other Services [ Library Home | DNS & BIND | TCP/IP | sendmail | sendmail... communication between the organization's various networks Private networks that interconnect the various parts of an organization are often called enterprise networks When those private networks use the information services applications that are built on top of TCP/IP, particularly Web servers and browsers, to distribute internal information, those networks are called intranets There are a few basic... emphasize price However, if you are connecting a full network to the Internet, you may want an ISP that can provide network address, name service, Web services, and other features that your network might need Previous: 3.8 Summary 3.8 Summary TCP/IP Network Administration Book Index Next: 4.2 Basic Information 4.2 Basic Information [ Library Home | DNS & BIND | TCP/IP | sendmail | sendmail Reference | Firewalls... at how the network administrator arrives at each of the required values 4.2.1 Obtaining an IP Address Every interface on a TCP/IP network must have a unique IP address If a host is part of the Internet, its IP address must be unique within the entire Internet If a host's TCP/IP communications are limited to a local network, its IP address only needs to be unique locally Administrators whose networks . same network. Gateways are needed to communicate with systems on other networks. If the hosts on your network need to communicate with computers on other networks,. this discussion are IP routers that interconnect TCP/IP networks. If you are not interconnecting TCP/IP networks, you do not need an IP router. Neither