Compaq TCP/IP Services for OpenVMS Concepts and Planning Part Number: AA-Q06TF-TE April 2002 Software Version: Compaq TCP/IP Services for OpenVMS Version 5.3 Operating Systems: OpenVMS Alpha Version 7.2–2, 7.3 OpenVMS VAX Version 7.2, 7.3 This manual describes concepts and planning tasks to prepare you to use the Compaq TCP/IP Services for OpenVMS product.
© 2002 Compaq Information Technologies Group, L.P. COMPAQ, the Compaq logo, Alpha, OpenVMS, Tru64, VAX, VMS, and the Compaq logo are trademarks of Compaq Information Technologies Group, L.P., in the U.S. and/or other countries. Microsoft, MS-DOS, Visual C++, Windows, and Windows NT are trademarks of Microsoft Corporation in the U.S. and/or other countries. Intel, Intel Inside, and Pentium are trademarks of Intel Corporation in the U.S.
Contents Preface 1 Introducing Compaq TCP/IP Services for OpenVMS 1.1 1.1.1 1.1.2 1.1.3 1.1.4 1.2 1.2.1 1.3 1.3.1 1.3.2 1.3.3 1.3.4 1.4 2 1–2 1–3 1–3 1–3 1–4 1–5 1–5 1–5 1–5 1–6 1–6 1–7 1–7 Understanding OpenVMS and UNIX Implementations 2.1 2.1.1 2.1.2 2.2 2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.2.6 2.2.7 2.2.8 2.2.9 2.2.10 2.2.11 2.3 2.4 3 Overview of TCP/IP Services .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. Data Link Layer .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .
3.3.1 3.3.2 3.3.3 3.4 4 4.6.5 4–1 4–2 4–2 4–3 4–3 4–3 4–4 4–4 4–4 4–4 4–5 4–5 4–7 4–7 4–7 4–9 Network Time Protocol (NTP) .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. Time Distributed Through a Hierarchy of Servers . .. .. .. .. .. .. .. .. How the OpenVMS System Maintains the System Clock . .. .. .. .. How NTP Adjusts System Time . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. Configuring the Local Host . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..
6.1.2 6.1.3 6.1.4 6.1.5 6.2 6.2.1 6.2.2 6.2.3 6.3 6.3.1 6.3.2 6.3.3 6.3.4 6.3.5 7 6–2 6–2 6–2 6–3 6–5 6–5 6–6 6–6 6–6 6–7 6–7 6–8 6–8 6–8 Connectivity Services 7.1 7.2 7.2.1 7.2.2 7.2.3 7.3 7.3.1 7.3.2 7.3.3 7.3.4 7.3.5 7.4 7.5 8 How to Access Mail Messages from the POP Server .. .. .. .. .. .. .. .. How the POP Server Handles Foreign Message Formats . .. .. .. .. How the POP Server Authorizes Users . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. Understanding POP Message Headers . .. .. .. .. .. .. ..
8.9.2 Reverse Zone File .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 8.9.3 Loopback Interface Files .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 8.9.4 Hints File .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 8.10 BIND Resolver .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 8.10.1 Default Domain .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..
2–12 3–1 5–1 5–2 5–3 6–1 6–2 6–3 6–4 6–5 6–6 6–7 7–1 9–1 NFS Server Features Available to Non-OpenVMS Clients . .. .. .. .. .. .. OpenVMS VAX and OpenVMS Alpha Similarities and Differences .. GATED Protocols and RFCs .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. DHCP IP Address Allocation Methods .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. SNMP Components . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..
Preface An open communications standard defined by the worldwide networking community, TCP/IP consists of numerous application, routing, transport, and network management protocols. These protocols enable any connected host to communicate with any other connected host, without needing to know details about the other host or the intervening network topology. Computers and networks from different manufacturers running different operating systems can interoperate seamlessly.
Related Documentation The following table lists the documents available with this version of Compaq TCP/IP Services for OpenVMS: x Manual Contents Compaq TCP/IP Services for OpenVMS Concepts and Planning This manual introduces TCP/IP Services and provides conceptual and planning information to help you configure and manage the product.
Compaq TCP/IP Services for OpenVMS Sockets API and System Services Programming This manual describes how to use the Sockets API and OpenVMS system services to develop network-based applications. Compaq TCP/IP Services for OpenVMS SNMP Programming and Reference This manual describes the Simple Network Management Protocol (SNMP) and the SNMP application programming interface (eSNMP).
Reader’s Comments Compaq welcomes your comments on this manual. Please send comments to either of the following addresses: Internet: openvmsdoc@compaq.com Mail: Compaq Computer Corporation OSSG Documentation Group, ZKO3-4/U08 110 Spit Brook Rd. Nashua, NH 03062-2698 How to Order Additional Documentation Visit the following World Wide Web address for information about how to order additional documentation: http://www.openvms.compaq.
directory specifications and for a substring specification in an assignment statement. | In command format descriptions, vertical bars separate choices within brackets or braces. Within brackets, the choices are optional; within braces, at least one choice is required. Do not type the vertical bars on the command line. {} In command format descriptions, braces indicate required choices; you must choose at least one of the items listed. Do not type the braces on the command line.
1 Introducing Compaq TCP/IP Services for OpenVMS The Compaq TCP/IP Services for OpenVMS product is the OpenVMS implementation of the industry-standard TCP/IP suite of communications protocols.
1.1 Overview of TCP/IP Services TCP/IP Services provides support for several protocols at every level of the TCP/IP model’s protocol layers. • Data Link layer • Internet layer • Transport layer • Application layer Figure 1–1 shows the various layers and protocols of the TCP/IP model. A description of each layer and protocol follows the figure.
1.1.1 Data Link Layer At the base of the TCP/IP layers, the Data Link layer formats data and provides services that directly access the physical network. This layer also receives data that is routed from the Internet layer and transmits the data to its destination, converting logical IP addressesto physical addresses of the network adapter or network interface cards (NICs) using the Address Resolution Protocol (ARP).
1.1.4 Application Layer The top layer of the TCP/IP protocol suite, the Application layer handles the details of the particular application, protocol, or user command; it is not concerned with the movement of data across the network. TCP/IP Services supports the following TCP/IP applications, protocols, and user services: Remote Computing Services Remote computing applications enable networked users to run software on remote systems.
Electronic Mail Services Communication functions such a electronic mail are vital both within an organizational internet and across the Internet worldwide. The electronic mail components of TCP/IP Services are: Simple Mail Transfer Protocol (SMTP) is the TCP/IP standard protocol for transferring electronic mail messages from one system to another. IMAP is the Internet Message Access Protocol. IMAP enables clients to access email messages and folders from an IMAP server and synchronize them locally.
• Many application developers are familiar with the programming environment. • In addition to the TCP/IP protocols, there are options for other types of protocols. For more details, refer to the Compaq TCP/IP Services for OpenVMS Sockets API and System Services Programming manual. 1.3.2 OpenVMS QIO System Service Interface The standard I/O programming interface on OpenVMS uses the QIO (queue input/output) system services.
• Library of RPC function calls • Portmapper service, which is a service that client programs can use to determine the port number that another service uses. Clients use the Portmapper Service for NFC, PC-NFS, and RPC applications. • External data representation (XDR) routines For more details, refer to the Compaq TCP/IP Service ONC RPC Programming manual. 1.3.
2 Understanding OpenVMS and UNIX Implementations An important step in planning a network host implementation is to gain an understanding of the computing environments in which the network services will run. Compaq Tru64 UNIX implementations of TCP/IP Services are often ported to OpenVMS. As a result, they often appear to be identical. However, there are many significant differences. This chapter describes key implementation differences between UNIX and OpenVMS networks.
An open system allows the OpenVMS operating system, whether powered by Alpha or VAX, to interoperate efficiently with Compaq Tru64 UNIX and with other vendors’ operating systems, particularly with Windows NT and other UNIX operating systems. 2.1.2 Understanding the Middleware Concept Implementing open systems means using the right middleware between the operating system and the hardware platform and applications. Consistent middleware affords interoperability and portability when and where it is needed.
access directories and files on remote computers transparently, as if they were on the local system. NFS accomplishes this because it is implemented on the both the remote and the local computer. NFS protocol achieves portability between different machines, operating systems, network architectures, and transport protocols through the use of Remote Procedure Call (RPC) and External Data Representation (XDR).
Figure 2–2: Comparison of UNIX Directory and OpenVMS Directory Hierarchies Tru64 UNIX / bin public news.txt usr tools.dat dev jay profile jones smith work prog_1.c calc.pas etc accounting.com done.txt OpenVMS DBB1 DBB2 [000000] Master file directory (MFD) DUA0 DUA1 DUA2 [000000] Master file directory (MFD) PUBLIC.DIR JAY.DIR JONES.DIR SMITH.DIR NEWS.TXT;2 TOOLS.DAT;2 LOGIN.COM;4 WORK.DIR PROG_1.C;2 ACCOUNTING.COM;3 CALC.PAS;2 DONE.TXT;2 VM-0897A-AI 2.2.
Table 2–2: File Specification Differences OpenVMS UNIX Files are delimited in the following way: The slash (/) is the only delimiter that the UNIX file specification format uses. The first slash in a UNIX file specification represents the root directory. Subsequent slashes separate each element of the file specification (the directories from the other directories and the file name). In theory, there is no limit to the number of directory levels in a UNIX file specification.
Table 2–3: Absolute and Relative File Specification Differences OpenVMS UNIX The relative path for file calc;1 in directory usr:[jones] is: [.accounting.calc;1] The absolute path is: usr:[jones.accounting.calc;1] The relative pathname for file calc in directory /usr/jones is accounting/calc The absolute pathname is /usr/jones/accounting/calc On UNIX systems, absolute pathnames use the entire directory path that leads to the file, beginning with the root, which is represented by an initial slash.
Table 2–5: Case-Sensitivity Differences OpenVMS (ODS-2) UNIX Stores everything in uppercase. For example, any case variations of the following file name is stored in uppercase: CHAPTER_ONE.TXT;1 Regards uppercase and lowercase characters as different characters. For example, on a UNIX system, the following file names represent three different files: • CHAPTER_ONE.TXT • Chapter_One.Txt • chapter_one.txt 2.2.6 File Types Table 2–6 describes the file type differences between OpenVMS and UNIX.
Table 2–8: Link Files Differences OpenVMS UNIX Files can exist without links. Files cannot exist without links. Hard Links OpenVMS systems allows you to perform a function similar to hard links with the SET FILE/ENTER and SET FILE/REMOVE commands. The OpenVMS operating system does not maintain a count of links to a file. As a result, you can delete a file without deleting its links. Hard Links Hard links allow users to share the same file under different pathnames. A hard link cannot span file systems.
Table 2–10: File Ownership Differences OpenVMS UNIX The OpenVMS operating system controls file ownership and access through a user identification code (UIC). A UIC is a 32-bit value that consists of a 14-bit group number, a 16-bit member number, and 2 reserved bits. Each user of the system has a UIC defined in the SYSUAF file. Access to objects depends on the relationship between the UIC of the accessing process and the UIC of the object (the file or directory).
Table 2–11: Comparison of File Protection (cont.) Protection levels READ (R) WRITE (W) EXECUTE (E) – Controls file execution and directory search access DELETE (D) read (r) — The user has a matching UIC write (w) — Controls unlinking files to the directory. execute (x) — Controls file execution and directory search access A file is deleted if it is unlinked from the directory and had no links in other directories. Write access to the directory is refused.
2.4 Determining Which File System to Use The first step in managing your TCP/IP Services system is to decide which file system to use.
_____________________ Decision Point _____________________ Your file system choice depends on your environment and the user needs on the NFS client host. Consider using an OpenVMS file system if: Your users share most files between your OpenVMS system and another OpenVMS host, or between your OpenVMS system and a UNIX client. Your client users need to maintain multiple versions of files. You share files between users on OpenVMS and users on NFS clients.
3 OpenVMS Server and Network Configurations There are several server and network configurations to consider before installing TCP/IP Services for OpenVMS.
Table 3–1: OpenVMS VAX and OpenVMS Alpha Similarities and Differences Component Similarities OpenVMS VAX Differences OpenVMS Alpha Differences DIGITAL Command Language (DCL) Essentially the same on both systems. None Refer to the few exceptions in the OpenVMS Compatibility Between VAX and Alpha guides available on line. DCL Help Most DCL help text is common to both systems. System-specific information is identified by the phrase “On VAX.
utility, the Librarian utility, the OpenVMS Debugger (also known as the symbolic debugger), the Delta/XDelta Debugger, and run-time libraries. However, some TCP/IP Services components are available only on OpenVMS Alpha, including: • BIND Version 9 • IMAP • PPP These components are introduced later in this manual.
Each node (as a member of the host configuration in the cluster) retains a separate IP address. This is beneficial for troubleshooting the individual node because you can ping the specific node to see whether it is running. All of the TCP/IP services support automatic failover and can run on multiple nodes in an OpenVMS Cluster. For example, if more than one node in the cluster is running the NFS server, the cluster can appear to the NFS client as a single host.
3.3.1 Multihomed Computers Individual host computers can have multiple network interface cards per computer. Such a computer is called multihomed. These physical interfaces can be connected to different types of networks, such as Ethernet, FDDI, Token Ring, asynchronous transfer mode (ATM), Gigabit Ethernet, and serial communications lines. Each physical interface is associated with one device driver (network interface). A single network interface can have more than one IP address.
3.3.3 Pseudointerfaces To use extended routing, you can define pseudointerfaces. A pseudointerface is a data structure that extends subnet routing using a network interface. Each network interface has one name and at most nine pseudointerface names. Each network interface and pseudointerface has its own IP address, network mask, and broadcast mask.
• Configuring serial lines For detailed descriptions of OpenVMS Alpha and VAX similarities and differences, refer to A Comparison of System Management on OpenVMS AXP and OpenVMS VAX. For complete information about supported devices and configurations, refer to the Guidelines for OpenVMS Cluster Configurations and the OpenVMS Cluster Software Software Product Description (SPD). For complete information about setting up and using an OpenVMS Cluster environment, refer to the OpenVMS Cluster Systems manual.
4 OpenVMS Operating System TCP/IP Features The OpenVMS operating system contains a number of features that are of specific benefit to the TCP/IP environment.
You can also use UNIX management commands to manage some components of TCP/IP Services. To use UNIX management commands at the DCL prompt, run the following command procedure: $ @SYS$MANAGER:TCPIP$DEFINE_COMMANDS Then enter UNIX commands as you would on a Tru64 UNIX system. TCP/IP management commands are described fully in the Compaq TCP/IP Services for OpenVMS Management Command Reference manual, and in the TCP/IP Services online help.
If you are unable to analyze a process dump with the debugger, use the System Dump Analyzer (SDA) utility. Refer to the ANALYZE/CRASH command in online help for more information. For example: $ ANALYZE/CRASH billsystem.dmp OpenVMS (TM) Alpha system dump analyzer ...analyzing a compressed process dump... Dump taken on 24-JUL-2002 12:03:40.95 SDA> For details, refer to the OpenVMS VAX System Dump Analyzer Utility Manual and the OpenVMS Alpha System Dump Analyzer Utility Manual. 4.
4.5 ODS-5 and ODS-2 File Structures OpenVMS implements On-Disk Structure Level 5 (ODS-5). This structure provides the basis for creating and storing files with extended file names. The format was introduced for compatibility with other file systems, such as Windows. You can choose whether or not to convert a volume to ODS-5 on your OpenVMS Alpha systems.
• Privileged applications that perform filename parsing and need to access ODS-5 file names or volumes should be analyzed to determine whether they require modification. On ODS-5 volumes, existing applications and layered products that are coded to documented interfaces, as well as most DCL command procedures, should continue to work without modification.
• Updates the related printcap database. • Creates and starts queues. • Allows you to add commands to the automatic startup and shutdown command procedures. To print, users at an OpenVMS client enter the DCL command PRINT. Users working on UNIX clients typically enter the lpr command. To use the Compaq TCP/IP Services for OpenVMS network printer services, you need the following: • The remote host name. • The name of the remote print queue or the local queue name.
• Displaying print queue status • Canceling print jobs • Receiving on local (OpenVMS system) print queues print jobs initiated from a user on a UNIX system • Getting a "finished" notification through SMTP mail 4.6.2 TELNET Print Symbiont The TELNET print symbiont (TELNETSYM) provides remote printing services that enables OpenVMS printing features not available with the LPR/LPD print service. With TELNETSYM, the local OpenVMS system drives a remote printer as if it were directly connected.
Determine which printers you want to make available to your server community. Some considerations regarding printers include: • Location Select printers that are closest to the physical location of users who require their output. • Cost of use You might want to restrict access to expensive-to-use printers rather than make them available to all network users.
4.6.5 PC-NFS The PC-NFS server provides authentication and print services for PCs running NFS. Users on a PC client can associate the name of the PC printer with an OpenVMS print queue and can print files to the associated queue. However, Compaq recommends that PC clients use other mechanisms for accessing OpenVMS print queues. To access the NFS server, PC users must have an entry in the proxy database and must have corresponding OpenVMS accounts on the server.
5 Network Server Services This chapter describes key concepts for the following network server features: • Network Time Protocol (NTP) • Routing • Remote client management (BOOTP/DHCP) • File Transfer Protocol (FTP) • SNMP Things to Consider In planning your TCP/IP Services for OpenVMS, consider the following: • Will the system serve as a time server and at what stratum? Where does the authoritative time come from? • Do I need to remote boot any clients? Which kinds? • Will the system serve a
5.1.1 Time Distributed Through a Hierarchy of Servers In the NTP environment, time is distributed through a hierarchy of NTP time servers. Each server adopts a stratum that indicates how far away it is operating from an external source of UTC. NTP times are an offset of UTC. Stratum 1 servers have access to an external time source, usually a radio clock. A stratum 2 server is one that is currently obtaining time from a stratum 1 server; a stratum 3 server gets its time from a stratum 2 server, and so on.
5.1.4 Configuring the Local Host As the system manager of the local host, you determine which network hosts to use for synchronization and for populating an NTP configuration file with a list of the participating hosts. You can configure NTP hosts in one or more of the following modes: • Client/server mode This mode indicates that the local host wants to obtain time from the remote server and is willing to supply time to the remote server, if necessary.
5.2.1 Static Routing Because static routing requires manual configuration, it is most useful when the number of gateways is limited and when routes do not change frequently. For information about manually configuring routing, refer to the Compaq TCP/IP Services for OpenVMS Management guide. 5.2.2 Dynamic Routing Complex environments require a more flexible approach to routing than a static routing table provides.
Table 5–1: GATED Protocols and RFCs Protocol Description Described in this RFC Routing Information Protocol (RIP) supports both Versions 1 and 2 RIP is a commonly used interior protocol that selects the route with the lowest metric (hop count) as the best route. RFCs 1058, 1723 Open Shortest Path First (OSPF) Version 2 Another interior routing protocol, OSPF is a link state protocol (shortest path first). It is better suited than RIP for use in complex networks with many routers.
from among identical routes the one with the lowest reference count. If there is more than one lowest reference count, it uses the lowest use count. Although ROUTED allows multiple default routes, it does not monitor interface states. Conversely, GATED monitors interface status changes; however, it does not allow multiple default routes. For information about configuring dynamic routing with GATED, refer to the Compaq TCP/IP Services for OpenVMS Management guide. 5.
• A set of rules for delivering client-specific configuration parameters from a DHCP server to a client The server and client communicate to accomplish the following steps: 1. When a DHCP client boots, it broadcasts a DHCP request, asking that any DHCP server on the network provide it with an IP address and configuration parameters. 2. A DHCP server on the network that is authorized to configure this client sends the client a reply that offers an IP address. 3.
Table 5–2: DHCP IP Address Allocation Methods Method Applicable Client Description Dynamic DHCP and BOOTP The DHCP server assigns an IP address from an address pool to a client for a specified amount of time (or until the client explicitly relinquishes the address). Addresses no longer needed by clients can be reused. Use dynamic allocation when: • Clients will be connected to the network only temporarily.
5.3.3 Relationship Between DHCP and BOOTP From the client’s perspective, DHCP is an extension of the BOOTP functionality. DHCP allows existing BOOTP clients to operate with DHCP servers without having to change the client’s initialization software. Based on the format of BOOTP messages, the DHCP message format does the following: • Captures the BOOTP relay agents and eliminates the need for a DHCP server on each physical network segment. • Allows existing BOOTP clients to operate with DHCP servers.
5.4.1 FTP (File Transfer Protocol) FTP is a TCP/IP standard, high-level protocol used to transfer files bidirectionally. FTP enables users to access files interactively, list directories on a remote host, delete and rename files on the remote host, and transfer files between hosts. FTP also provides authentication control, which requires users or clients to correctly enter a login name and password to the server before requesting file transfers.
• RCP – Allows files to be copied between remote hosts. • RLOGIN — Provides interactive access to remote hosts. • RSH — Passes a command to a remote host for execution. • REXEC – Authenticates and executes RCP and other commands. • RMT/RCD – Provides remote access to magnetic tape and CD-ROM drives. In addition to password authentication, the R commands use a system based on trusted hosts and users. Trusted users on trusted hosts are allowed to access the local system without providing a password.
5.5 Simple Network Management Protocol (SNMP) The Simple Network Management Protocol (SNMP) is network management technology that facilitates the management of a TCP/IP network or internet in a vendor-independent manner. SNMP enables a network administrator to manage the various network components using a set of well-known procedures understood by all components, regardless of the original manufacturers.
Table 5–3: SNMP Components (cont.) SNMP utility programs Acts as a simple client to obtain a set of values for a MIB and to listen for and send trap messages. For information about using the MIB utility programs, refer to the Compaq TCP/IP Services for OpenVMS SNMP Programming and Reference guide. SNMP subagent example Implements an example based on the chess game; includes executable and source code. 5.5.
6 Mail Services Mail Services are an extremely important part of TCP/IP Services. Everyone who uses the network — from administrators, to programmers, to users accesses — this service on a regular basis. This chapter describes Post Office Protocol (POP), SMTP, and IMAP.
The POP server uses security features provided in the protocol and in the OpenVMS operating system, as well as additional security measures. These methods provide a secure process that minimizes the possibility of inappropriate access to a user’s mail file on the served system. You can modify the POP server default characteristics, and you can implement new characteristics by defining logical names described in the Compaq TCP/IP Services for OpenVMS Management guide. 6.1.
Table 6–1: POP User Authorization Methods Method Description Shared secret password Most secure POP server access method. Initiated by the client system through the APOP command. Allows a user to become authorized by the POP server without having to send a password over the network. Eliminates a potential path for unauthorized users to obtain a password and break into the system. POP requires a shared secret password from any user who wants to read mail using the APOP authorization method.
Table 6–2: Forwarded POP Mail Messages Header (cont.) From: OpenVMS message From: field. Rebuilt to ensure RFC 822 compatibility. To: OpenVMS Mail To: field. Not rebuilt. CC: OpenVMS Mail CC: field. Not rebuilt. Subject: OpenVMS Mail Subj: field. Not rebuilt. X-VMS-From: OpenVMS Mail From: field. Not rebuilt. X-POP3-Server: Server host name and POP version information. Sent only if logical name TCPIP$POP_SEND_ID_HEADERS is defined. X-POP3-ID: Message UID.
6.2 Simple Mail Transfer Protocol (SMTP) To be reliable, electronic mail systems must be able to cope with situations in which the recipient is temporarily unavailable; for example, if the recipient’s host is down or off line. Mail must also be able to handle situations in which some of the recipients on a distribution list are available and some are not. Simple Mail Transfer Protocol (SMTP) is the TCP/IP standard protocol for transferring electronic mail messages from one system to another.
Table 6–4: SMTP Client Commands Command Description HELLO Identifies the originating host to the server host. Use the /DOMAIN qualifier to provide the name of the originating host. MAIL FROM: Identifies the address at which undeliverable mail should be returned. Usually is the originating host. RCPT TO: Address of the intended receiver. If sending mail to multiple recipients, use one RCPT TO command for each recipient.
protocol as defined in RFC 2060. The supported clients used to access e-mail are PC clients running Microsoft Outlook or Netscape Communicator. By default, the IMAP Server is assigned port number 143. All IMAP clients connect to this port. The following sections review the IMAP process and describe how the TCP/IP Services software implements IMAP. If you are not familiar with IMAP, refer to RFC 2060 or introductory IMAP documentation for more information. 6.3.
6.3.3 How the IMAP Server Handles Foreign Message Formats The IMAP Server determines the correct format for common file types. It does this by checking the beginning of the file for a recognizable file header that matches a set contained in the configuration file TCPIP$IMAP_HOME:TCPIP$IMAP_MAGIC.TXT (analogous to the magic files found on UNIX systems). If a matching file header is found, the server can let the client know the MIME type and subtype of the file. 6.3.
client. The same is true for To: and CC: headers if the user requests that a reply be sent to other listed recipients. Therefore, the IMAP Server rebuilds these fields in compliance with RFC 822 before sending the header to the IMAP Client. Table 6–7 describes the different types of addresses that can appear in the OpenVMS Mail address fields.
For more information about the SET MX_RECORDS command, see the Compaq TCP/IP Services for OpenVMS Management Command Reference guide.
7 Connectivity Services Compaq TCP/IP Services provides several ways to connect to the network. This chapter discusses the following connectivity methods: • TELNET • PPP and SLIP • NFS • XDM • DECnet over TCP/IP Things to Consider In planning your TCP/IP Services for OpenVMS configuration, consider the following: • Should I configure SLIP or PPP? • Should I configure for DECnet over TCP/IP? • Do I need to set up NFS? 7.
you can configure a PPP interface on your system without knowing your own IP address, and you can obtain the IP address when you connect to a remote system. Before you establish SLIP communication with a remote host, however, you must obtain the IP address for the host’s serial interface and assign IP addresses for each interface you configure on the local host. When using SLIP, consider placing each serial line in a separate subnetwork.
7.3 Network File System (NFS) The Network File System (NFS) server software lets you set up file systems on your OpenVMS host for export to users on remote NFS client hosts. These files and directories appear to the remote user to be on the remote host even though they physically reside on the local system. After the NFS server is installed on your computer, you must configure the server to allow network file access.
Each file system is a multilevel directory hierarchy: on OpenVMS systems, the top level of the directory structure is the master file directory (MFD). The MFD is always named [000000] and contains all the top-level directories and reserved system files. On UNIX systems or with a container file system, the top-level directory is called the root. For information about container file systems and about selecting a file system, refer to Chapter 2. 7.3.
• Identity of the requester as a UID/GID pair • Requested NFS operation and any data associated with the operation The server searches its proxy database for an entry that corresponds to the requester’s UID/GID pair. If the UID maps to an OpenVMS account, the server grants access to the file system according to the privileges set for that account. In the following example, the proxy entry maps a client user with UID=15/GID=15, to the OpenVMS account named ACCOUNT2.
• A workstation that has the X Window System software installed and configured • A PC running Windows or Windows NT and some X Window System software, such as eXcursion or Exceed The X Display Manager (XDM) is an X client that manages the login process of a user’s X window session. XDM is responsible for displaying a login screen on a display specified by an X server, establishing an X window session, and running scripts that start other X clients.
Join two existing DECnet networks without renumbering. Run IP-only traffic in part of the backbone and continue using DECnet applications and user interfaces without extra costs and retraining. When running DECnet over TCP/IP, you can use an IP host name such as the one in the following example: $ set host remotehst6.acme.com For more information about making connections using DECnet over TCP/IP, see the DECnet-Plus for OpenVMS documentation.
8 Domain Name System/BIND (DNS/BIND) TCP/IP Services for OpenVMS software supports the Berkeley Internet Name Domain (BIND) service, which is a popular implementation of the Domain Name System (DNS). BIND has been ported to many platforms, including UNIX, Windows NT, and OpenVMS. Before you add BIND servers to your network, you should understand the basic BIND service concepts as they apply to the TCP/IP Services for OpenVMS product.
the network. BIND can also provide information on available mail servers and well-known services for a domain. Based on a client/server model, BIND servers maintain databases of host names, IP addresses, mail records, text records, and other network objects. When client systems require this information, they query the servers. IP address space allocation is one of the many duties for which ICANN (Internet Corporation for Assigned Names and Numbers), a non-profit corporation, assumes responsibility.
• Controlling the assignments of the host and domain names The domain administrator furnishes users with access to names and name-related information both inside and outside the local domain. 8.4 Domain Names The InterNIC assigns names for all top-level domains as well as domains directly below the top-level domains. Individuals are responsible for assigning lower-level domains and host names. Each domain has a label. For example, the label for the top-level domain for commercial organizations is com.
are easier to keep track of if they are short. The sum of all the label characters and label lengths cannot exceed 255. _________________________ Note _________________________ Domain names are not case sensitive. However, the case of entered names is preserved whenever possible. For example, the fully qualified domain name euro.sales.compaq.com is broken down as follows (from right to left): • The com label refers to the commercial top-level domain.
8.7 BIND Server Functions If a network consists of relatively few hosts, host name to IP address translations can be accomplished by using a centralized hosts database file. As soon as a network connects to another network, or when the number of hosts grows large, a more robust method for performing host name/IP address translation is required. In particular, when a network is part of the worldwide internet, no single database can keep track of all addressing information.
8.7.2 Master Name Server There are two types of master servers: a master name server and a slave name server (also called a secondary master name server). The master server is the primary authority for the zone. The master server has complete information about the zone, and it stores the information in its database files. If network information changes, those changes are captured in the master server’s database files.
8.7.6 Configurations Without Internet Access You can run the BIND service on a local network that does not have internet access. In this configuration, the servers resolve local queries only. Any request that depends on Internet access goes unresolved. 8.7.7 Zone Transfers Zone transfers are the process by which slave servers obtain their zone data. When a slave server starts up and periodically thereafter, the server checks whether its data is up to date.
_________________________ Note _________________________ You should not manually edit the zone database file of a zone that is being dynamically updated. 8.8 BIND Server Configuration Files BIND reads information from an ASCII file called TCPIP$BIND.CONF. On UNIX systems, the file name is named.conf.
IN-ADDR.ARPA zone file for each network represented in the master zone file including the loopback interface. 8.9.3 Loopback Interface Files The loopback interface files define the zone of the local loopback interface, known as LOCALHOST. There is a master zone file and a reverse zone file for LOCALHOST. The resource record for this file defines LOCALHOST with a network address of 127.0.0.1. TCP/IP Services for OpenVMS configuration procedure creates these two files and calls them LOCALHOST.DB and 127_0_0.
For More Information For detailed information about DNS/BIND, refer to the Compaq TCP/IP Services for OpenVMS Management guide.
9 IPv6 Internet Protocol Version 6 (IPv6), as defined in RFC 2460, is the replacement Network layer protocol for the Internet and is designed to replace Internet Protocol Version 4 (IPv4). IPv6 also changes the structure of the Internet architecture. This does not mean that you have to deploy IPv6 all at once across your network; rather, you can make the change in stages because IPv6 and IPv4 were designed to interoperate.
_________________________ Note _________________________ This site lists Internet-Drafts documents, all of which are works in progress and subject to change at any time. The Internet Protocol Version 6 (IPv6) was designed to support mobility through features like its extensible header structure, address autoconfiguration, security (IPsec) and tunneling. mobile IPv6 builds upon these features.
Away from home, the mobile node sends a home address option to inform the receiver of its home address enabling the receiver to correctly identify the connection to which the packet belongs. When the mobile node returns to its home link, the mobile node sends a binding update to the home agent and to the correspondent node to clear the bindings. For more information about mobile IPv6, refer to the TCP/IP Services release notes. 9.
For more information about tunnels refer to Compaq TCP/IP Services for OpenVMS Guide to IPv6. TCP/IP Services Version 5.3 includes support for a new tunnel IPv6 transition mechanism called 6to4, as defined in RFC 3056. For more information about the 6to4 mechanism, refer to the TCP/IP Services release notes. 9.
Figure 9–1: Routing IPv6 Traffic from Host A to Host F Host A v4/v6 Host B Host C v4/v6 v4/v6 Router A v4/v6 Department A v4 v4 Host D Host E v4/v6 Host F Router B v4/v6 Department B Router C v4 v4 v4 Host G Host H v4/v6 Host I Department C VM-0950A-AI In Figure 9–2, to communicate with host I, host A sends an IPv6 packet to router A. Router A forwards the IPv6 packet to router B.
Figure 9–2: Routing IPv6 Traffic from Host A to Host I Host A v4/v6 Host B Host C v4/v6 v4/v6 Router A v4/v6 Department A v4 v4 Host D Host E v4/v6 Host F Router B v4/v6 Department B Router C v4 v4 v4 Host G Host H v4/v6 Host I Department C VM-0951A-AI In Figure 9–3, to communicate with host A, host I encapsulates the IPv6 packet and sends the IPv4 packet over a host-to-router tunnel to router B. From there, router B decapsulates the IPv4 packet and routes the IPv6 packet to host A.
Figure 9–3: Routing IPv6 Traffic from Host I to Host A Host A v4/v6 Host B Host C v4/v6 v4/v6 Router A v4/v6 Department A v4 v4 Host D Host E v4/v6 Host F Router B v4/v6 Department B Router C v4 v4 v4 Host G Host H v4/v6 Host I Department C VM-0952A-AI 9.3.2 Intranet-to-Internet Scenario In this scenario, you add a v4/v6 router to your network and use it to communicate with the global Internet. The IPv6 hosts communicate with the v4/v6 router using IPv6.
Figure 9–4: Routing IPv6 Traffic from Host A to Host J Host A v4/v6 Host B Host C v4/v6 Host J v4/v6 Router A v4/v6 Department A Internet 6bone Point of Entry v4 v4 Host D Host E v4/v6 Host F Router B v4/v6 Department B Router C v4 v4 v4 Host G Host H v4/v6 Host I Department C VM-0953A-AI To communicate with the 6bone, host A sends the IPv6 packet to router A. Router A encapsulates the IPv6 packet and sends the IPv4 packet over a router-to-host tunnel to the 6bone point of entry.
Figure 9–5: Routing IPv6 Traffic from Host A to Host K Host A v4/v6 Host B Host C v4/v6 Host J v4/v6 Router A v4/v6 v4 Internet Department A v4 v4 Host D Host E Host K Host L v4/v6 v4 Router E v4/v6 Department D v4/v6 Host F Router B v4/v6 Department B Router C v4 v4 v4 Host G Host H v4/v6 Host I Department C VM-0954A-AI 9.4 Porting Existing IPv4 Applications The OpenVMS operating system provides the basic application programming interfaces (APIs) as defined in RFC 2553.
testing IPv6 on the 6bone. For more information about 6bone address allocation and assignment, refer to the 6bone home page at the following location: http://www.6bone.net After you contract with your ISP for a block of addresses, your deployment of IPv6 in your network begins the process of renumbering of your network. In IPv4, network renumbering was a difficult and time-consuming process. In IPv6, network renumbering is more dynamic.
For more information about configuring Domain Name System, refer to the Compaq TCP/IP Services for OpenVMS Guide to IPv6 manual. 9.8 Configuring IPv6 Routers Before you configure IPv6 routers, consider the following points: _____________________ Decision Point _____________________ Identify the interfaces over which to run IPv6. Decide whether you need a configured IPv4 tunnel for communications with other IPv6 nodes or networks.
• APIs and the AF_INET6 sockets • Developing applications that use AF_INET6 sockets and client/server code • Configuring the DNS/BIND server • Changing the resolver configuration to point to the local node for name lookups • Configuring IPv6 routers • Configuring an IPv6 host For more information about APIs and the AF_INET6 sockets, refer to the Compaq TCP/IP Services for OpenVMS Sockets API and System Services Programming guide.
Glossary This glossary defines terms that pertain to the features and operation of the Compaq TCP/IP Services for OpenVMS product. absolute path name A path name that starts with a slash (/); specifies a file that can be found by starting at the root of the file system and traversing the file tree. absolute time A specific date or time of day; specified in the following format: [dd-mmm-yyyy] [:hh:mm:ss:cc] . abstract syntax The description of a data structure that is independent of host structures or codes.
address resolution The process of relating an IP address to a hardware address, when both refer to the same device, for example, conversion of an IP address into the corresponding Ethernet, Token Ring, or FDDI hardware address. This may require broadcasting on a local network. See also Address Resolution Protocol.
of a client or server application. (2) Network management: Portion of an entity that responds to management requests and/or preprogrammed trap. agent access module The portion of an agent responsible for the agent’s end of SNMP. agent access point The instance of a connection between a client or director and a server or agent. agent address An address that specifies the information needed by a director to establish communications with the agent’s management interface.
Application layer The top-most layer in the Internet architecture model where the user interacts with an application such as Network File Service (NFS), File Transfer Protocol (FTP), and mail. application process A part of a distributed application running on a single host. application programming interface (API) A standardized set of routines that makes system functions available to programmers. architecture The structure of a system, a description of which can be used to recreate the system.
server returns a nonauthoritative answer when the server’s answer comes from its own cache. autonomous confederation A group of independent computer systems that trust each other regarding routing and reachability information; members believe information provided by other members in preference to information received from systems that are not part of the confederation. autonomous system (AS) A collection of networks controlled by one administrative authority.
request is executed once in a foreground process. If the mount request fails, the request is retried in a background process. This allows the local system to continue the boot procedure without waiting for the server to become available. bandwidth (1) Technically: The difference, in Hertz (Hz), between the highest and lowest frequencies of a transmission channel. (2) Typically: The amount of data that can be sent through a communications circuit.
block A contiguous unit of user information grouped together for transmission, such as the user data within a packet, excluding the protocol overhead. boot file A database file that BIND servers use to determine their type, the zones for which they have authority, and the location of other BIND database files. BOOTP The mnemonic for Bootstrap protocol. The protocol used for booting diskless systems remotely to a network. See also remote boot.
broadcast circuit A circuit on which multiple nodes are connected. A message can be transmitted to multiple receivers, and all nodes are adjacent. broadcast end-node adjacency An end node connected to the same broadcast circuit as the local node. See also adjacency. broadcast router adjacency An intermediate system (router) connected to the same broadcast circuit as the local node. See also adjacency. broadcast mask A mask used to interpret the IP address as a broadcast address.
canonical name The main or official name for a host; other names for the same host are aliases. In a BIND configuration, you specify the canonical name in a CNAME record of the named.hosts file. category phrase A BIND configuration logging statement phrase that specifies the different categories for which to log messages.
collision The condition in which two data packets are transmitted over a medium at the same time, making both unintelligible. common address notation The common way of expressing an Internet address. The 32-bit address uses four fields that are separated by periods; each field ranges from 0 to 255. communications link The physical medium connecting two systems. communications server A special-purpose standalone system dedicated to managing communications activities for other computer systems.
contention control The scheme of access control used by many networks. Control is distributed among the nodes of the network. Any node wanting to transmit can do so, accessing the network on a first-come, first-served basis. However, it is possible that two nodes are in contention, or start transmitting at the same time, in which case a collision occurs. Each node must then back off and retransmit after waiting a random period of time.
datagram A self-contained package of data carrying enough information to be routed from source to destination without reliance on earlier exchanges between source and destination or the transporting network. datagram fragment The result of fragmenting a datagram. Fragments carry a portion of data from the larger original and a copy of the original datagram header. The header fragmentation fields are adjusted to indicate the fragment’s relative position within the original datagram.
for the multiaccess network and assists in running the protocol. The designated router is elected by the HELLO protocol. destination address The IP address that specifies where a datagram is to be sent; contains the network and host identifiers. Any network or host. destination port A 2-octet value in the TCP and UDP header field that identifies the destination upper-level protocol for a packet’s data.
distributed processing The technology that enables the distribution throughout the network of computing power and storage facilities to user work areas, such as offices, laboratories, or machines on factory floors. distributed system A collection of computer systems, tied together by communications networks for the purpose of sharing resources; end users do not need to be aware of the physical location of the shared resources. DNS See Domain Name System.
dynamic routing A type of routing where a host or router talks to adjacent routers to learn what networks each router is connected to. Subsequently, the kernel’s routing tables are updated when the router learns new information. There are many routing protocols including Interior Gateway Protocols (RIP, OSPF) and Exterior Gateway Protocols (EGP and BGP). ephemeral port number A port number temporarily assigned to a client process for the duration of a session.
entity hierarchy A logical hierarchical tree structures of manageable entities in which child entities are below their parent entities. Children can be accessed only through their parents’ agent. entity identifier An attribute that specifically identifies an entity. See also attribute group. entity name A label associated with some entities used to identify or locate them for management purposes. entity type The subgrouping of an entity that determines its relationship to other entities.
FDDI See Fiber Distributed Data Interface. fetch/store operation The operation of two commands that allow a system manager to fetch a value from a data item or to store a value into a data item. Fiber Distributed Data Interface (FDDI) The high-speed (100 mb/s) networking standard based on fiber optics, established by the American National Standards Institute (ANSI); uses 1300 nanometer light wavelength. FDDI networks are limited to approximately 200 km in length, with repeaters every 2 km or less.
forwarder server The name server that processes recursive requests that a slave server cannot resolve locally; has access to the Internet. See also BIND server, cache server, primary server, secondary server, and slave server. forwarding information base The table that GATED uses internally to store routing information it learns from routing protocols is a routing table; also known as a routing information base, or RIB. The routing table is used to collect and store routes from various protocols.
gateway A communications device or program that passes data between networks having similar functions but dissimilar implementations. The term router is now used in place of the original definition of gateway. An intermediate destination by which packets are delivered to their ultimate destination. A host address of another router that is directly reachable through an attached network. As with any host address it may be specified symbolically. gateway client Another term for an access system.
heterogeneous network A network consisting of different network protocols or different operating system software, such as OpenVMS and UNIX. hierarchical routing Routing based on domains. Interdomain routers are responsible only for getting data to the right domain and intradomain routers take responsibility for routing within the domain. hop count The number of connections between two hosts, based on the number of different routers needed to traverse the distance between the two hosts.
IETF Internet Engineering Task Force. A large international community of network designers, operators, vendors and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet. Membership is open to everyone. See the http://www.ietf.org/ web site for more information. IGP See Interior Gateway Protocol. IMAP The Internet Message Access Protocol. IMAP enables clients to access email messages and folders from an IMAP server and synchronize them locally.
previous intermediate system on the route, and passes them on to the destination end system, or to the next intermediate system on the route. internet A shortened form of internetwork; a network of networks; interconnected TCP/IP networks that function as one large virtual network. Differs from the Internet by their lack of connectivity with the global Internet.
InterNIC Registration Services The Internet Network Information Center; organization that provides the Internet community with registration, directory, database, and information services. I/O status block (IOSB) A data structure associated with the $QIO system service. The IOSB holds information about how the I/O request completes. IP See Internet Protocol. IP address An address that identifies the connection between the network controller of a node using TCP/IP and the network cable.
limited use protocol A classification in Internet standards for protocols that are intended for use in limited circumstances; possibly because of their experimental state, specialized nature, limited functionality, or historic state. line printer daemon (LPR/LPD) The Compaq TCP/IP Services for OpenVMS remote printing services for UNIX and OpenVMS client hosts.
Logical Link Control The upper portion of the Data Link layer that presents a uniform interface to the user of the data link service, usually the Internet layer. loop node A local node that is associated with a particular address and is treated as if it were a remote node. All traffic to the loop node is sent over the associated address; used for loopback testing.
mask A means of subdividing networks using address modification. A mask is a dotted quad specifying the bits of the destination that are significant. Except when used in a route filter, GATED supports only contiguous masks. mask length The number of significant bits in the mask. master file directory (MFD) The root of an OpenVMS file system on a particular physical device. master server The name server that is the authority for a specific domain space. See also BIND server.
mount point A directory on an NFS client that is associated with a remote file system. The directory must exist before NFS can use it as a mount point. MTU See maximum transmission unit. multiaccess networks Physical networks that support the attachment of multiple (more than two) routers. Each pair of routers on such a network is assumed to be able to communicate directly. multicast A transmission of network traffic intended for multiple hosts (but not all connected hosts) within a network or internet.
neighbor Another router with which implicit or explicit communication is established by a routing protocol. Neighbors are usually on a shared network, but not always. This term is mostly used in OSPF and EGP. Usually synonymous with peer. neighboring routers Two routers that have interfaces to a common network. On multiaccess networks, routers are dynamically discovered by OSPF’s HELLO protocol.
network diameter The distance (number of hops) between the two nodes in the network with the greatest reachability distance. The reachability distance is the path with the fewest number of hops between two nodes. Network File System (NFS) A protocol developed by Sun Microsystems that allows a computer system to access files over a network as if they were on its local disks.
Network Time Protocol (NTP) The protocol that ensures accurate local timekeeping with reference to radio and atomic clocks located on the Internet; capable of synchronizing distributed clocks within milliseconds over long time periods. NFS See Network File System. NFS client The software that requests remote file services from an NFS server. Client system users access files that physically reside on an NFS server system. NFS server The software that provides remote file services to NFS clients.
nslookup The Compaq TCP/IP Services for OpenVMS utility that allows you to interactively query domain name servers (BIND servers) and helps you set up and manage the BIND server software. NTP See Network Time Protocol. NTP packet A message sent over the network that conforms to the Network Time Protocol format. This format includes space for recording the current time. See also poll.
a remote system (server) to execute a designated procedure, using supplied arguments, and the remote system returns the result to the local system. operator communication manager A system administration tool for communicating with users and operators on the system. OSPF (Open Shortest Path First) One of a class of interior gateway protocols, described in more detail in the OSPF section of gated.proto(4). open system A nonproprietary, interoperable system with communications software.
path cost The sum of the circuit costs along a path between two nodes. An OSPF (Open Shortest Path First) protocol metric. See metric and OSPF. path length The total distance (the number of circuits) between a source node and a destination node, measured in hops. Each line between systems, including routing nodes and end nodes, equals one hop. See also network diameter. path name A unique designation that identifies a directory or subdirectory.
Point-to-Point Protocol (PPP) A method for transmitting datagrams over serial point-to-point lines where a line is established between a remote host (usually over a telephone line) and another host acting as a gateway to a remote host. poll The sending of an NTP packet from a host to an NTP time server to request the current time. The server responds by recording the current time in the packet, then sending it back to the originating host. See also NTP packet.
primary server A BIND name server that maintains the database for a zone; secondary servers copy their information from primary servers. Also called primary master or master server. See also BIND server, cache server, forwarder server, and secondary server. printcap database The Compaq TCP/IP Services for OpenVMS database that maps local queues to printers on remote hosts; specifies local queues for LPD printing from remote hosts. Equivalent to the UNIX /etc/printcap file.
protocol stack The set of functions, one at each layer of the protocol stack, that work together to form a set of network services; each layer of the protocol stack uses the services of the module beneath it. proxy The mechanism whereby one system acts on behalf of another system in responding to protocol requests. uses a proxy mechanism to provide an OpenVMS identity (account) for each UNIX client by adding the name and identification codes of the client to a proxy database.
reassembly time A routing parameter that can be set to specify the length of time allowed for the reassembly of a message received in fragments. If the reassembly time expires before all fragments are received, the fragments are discarded. Record Management Services (RMS) The OpenVMS data management subsystem that defines the rules that govern the internal organization of and the methods of accessing file data.
resolver A mechanism or process to correlate a network host name into an appropriate network address in support of network applications; a network name resolver. See BIND resolver. reserved port An assigned port that provides services to unknown callers by providing a service contact point; reserved port numbers range from 1 to 255. resynchronization A process that enables the recovery of user information lost or corrupted during transfer across an association.
root name The element of a path name that identifies the target file system. root server An Internet name server that knows about all of the top-level domains on the Internet network; the master servers for the Internet root zone.
router_id An IP address used as unique identifier assigned to represent a specific router. This is usually the address of an attached interface. router solicitation A Router Discovery Protocol message sent out by a host to request router advertisement responses from a router. routing A Network layer function, implemented in intermediate systems, that determines the path along which data travels to its destination and the movement of that data. See also decision.
run-time library (RTL) A collection of OpenVMS procedures available to native mode images at run time; provide support routines for high-level language compilers. SCALE A TCP window scaling option; allows window information to be interpreted as being scaled by 1 to 16 powers of 2, thus increasing the size of the effective window. secondary server A master BIND server that receives authoritative database information from a primary server. Also known as slave server.
services database The Compaq TCP/IP Services for OpenVMS database created by default that contains one entry for each service configured. Simple Mail Transfer Protocol (SMTP) An Internet standard protocol for transferring electronic mail messages from one machine to another; specifies how two mail systems interact and the format of control messages they exchange to transfer mail.
socket pair The client IP address and port number, and the server IP address and port number that uniquely identify a TCP connection. source The IP header field that contains the IP address of the datagram’s point of origin. source port A 2-octet value in the TCP or UDP header field that identifies the upper-level application or protocol associated with the data in the segment. spanning tree A logical arrangement created by bridges in an extended LAN in which all LANs are connected and there are no loops.
subnet An organization of hosts within a network into logical groups. A network can be comprised of several subnets. The portion of a network, which might be a physically independent network, that shares a network address with other portions of the network and is distinguished by a subnet number. A subnet is to a network what a network is to an internet. subnet address A part of the Internet addressing scheme.
TCP/IP An Internet suite of protocols. See also Transmission Control Protocol and Internet Protocol. TELNET An Internet protocol for remote terminal connection. TELNET allows a user at one site to interact with remote timesharing systems at another site as if the user’s terminal were directly connected to the remote host. terminal access controller (TAC) A program and hardware that connects terminals to the Internet, usually using dialup modem connections.
The Time To Live (TTL) of an IP packet. Valid values are from 1 to 255 inclusive. time daemon The program running on a host that synchronizes the host’s hardware clock to Coordinated Universal Time in accordance with the protocols known as the Network Time Protocol. timeo A timeout option for the NFS mount command. TN3270 TELNET options that allows TELNET users to connect to hosts that support 3270 model terminals.
Trivial File Transfer Protocol (TFTP) The Internet protocol for file transfer with minimal capability and minimal overhead. The simple design of the facility is intended for use in application environments that do not require complex interactions among clients and servers. TFTP is a simple service running on top of UDP, using timeout and retransmission to ensure that data arrives. The sending side transmits a 512-byte, fixed-size file, and awaits an acknowledgment for each block before sending the next.
UUCP See UNIX-to-UNIX Copy Program. virtual circuit The network service that allows two processes to communicate as if they were directly connected, regardless of the structure of the underlying subnet. WAN See wide area network. well-known port A port number assigned for use by a specific network application for connections made with either UDP or TCP. Every implementation of TCP/IP that provides well-known services provides them with the well-known port numbers from 1 to 1023.
Acronym Meaning ASCII American Standard Code for Information Interchange ATM asynchronous transfer mode BBS Bulletin Board System BGP Border Gateway Protocol BIND Berkeley Internet Name Domain BOOTP Bootstrap Protocol bps bits per second BSD Berkeley Software Distribution CSLIP Compressed Serial Line Internet Protocol DCE Distributed Computing Environment DCL DIGITAL Command Language DEK data encryption key DES data encryption standard DNS Domain Name System eSNMP extensible S
Acronym Meaning MTU maximum transmission unit MX Mail exchange NAK negative acknowledgment NFS Network File System NIS Network Information Service NOC Network Operations Center NTP Network Time Protocol PDU protocol data unit PING Packet Internet Groper POP Post Office Protocol PPP Point-to-Point Protocol PSDN Packet Switching Data Network PWIP PATHWORKS Internet Protocol RARP Reverse Address Resolution Protocol RCP remote copy REXEC remote execute RFC Request for Comments
Acronym Meaning UDP User Datagram Protocol UID user identification (UNIX) UTC Coordinated Universal Time UUCP UNIX-to-UNIX Copy Program WAN wide area network WKS well-known server XDR external data representation Glossary–51
Index A Absolute domain name, 8–3 Access control, 7–4 Accounts remote user, 7–4 user, 5–11, 6–3t ACL (access control list), 2–9 definition, 2–9 ACP (ancillary control process), 1–5 Addressing ( See IP address ) Alias cluster, 3–3 node identifier, 3–3 Anonymous FTP, 5–10 Anonymous user access, 5–13 Application layer protocols, 1–4 FTP, 1–4 LPR/LPD, 1–4 NFS, 1–5 TELNET, 1–4 TFTP, 1–4 Application programming interface (API) Berkeley Sockets, 1–5 ONC RPC, 1–6 QIO, 1–6 SNMP, 1–7 Application support for PATHWORK
differences between OpenVMS and UNIX, 2–4 File structures differences between OpenVMS and UNIX, 2–8 File version numbers differences between OpenVMS and UNIX, 2–7 FINGER utility definition of, 1–4 FTP (File Transfer Protocol) definition of, 1–4 Fully qualified domain name, 8–3 G GATED (Gateway Routing Daemon), 5–4 H Hard links, 2–8 definition of, 2–11 Middleware definition of, 2–2 Migration definition of, 2–1 Mount point, 7–3 Multihomed, 3–5 definition of, 1–3 N Neighbor discovery, 9–1 Network server s
Proxy database, 7–4 Pseudointerface, 3–6 PWIP driver, 1–5 PWIPACP, 1–5 definition of, 1–4 TELNETSYM (TELNET print symbiont) definition of, 1–4 TFTP (Trivial File Transfer Protocol), 1–4 Q QIO programming interface , 1–6 R R commands definition of, 5–10 Remote commands ( See R commands ) Requests for Comments (RFCs) definition of, 1–7 Round-robin scheduling, 3–4 ROUTED (Routing Daemon), 5–4 RPC (remote procedure call)), 2–3 S Serial connection, 3–6 SLIP, 1–1 SMTP (Simple Mail Transfer Protocol) definit
