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In addition to the standard rlogin command, OpenVMS users on systems running TCP/IP software can use the alternative OpenVMS style commands to invoke RLOGIN programs. If you are logged in to an OpenVMS system that is running TCP/IP software, you can use the OpenVMS DCL command SET HOST/RLOGIN to invoke the RLOGIN client program (see Section 5.1.3).
TCP/IP provides the following file access protocols:
Both FTP and RCP can copy files to and from remote hosts. In addition, FTP can manage remote directories. FTP services download or upload files over the Internet (see Section 3.5.1).
FTP (File Transfer Protocol) is a simple way to move files across a TCP/IP network. The ftp command invokes a utility that permits the user to transfer files between hosts that do not support the same file systems (for example, between UNIX and OpenVMS hosts). Normally, the user executing the ftp command must have a password on the remote host. Some systems use the " anonymous FTP " service, which accepts a userid of anonymous and no password. (The standard convention is to provide a complete electronic mail address for the password.)
The FTP utility permits the user to transfer groups of files between local and remote hosts. First, the user establishes an interactive connection with the FTP server on the remote host by providing a user name and password. Once the connection is established, the user can invoke ftp commands to transfer text and binary files to or from the remote host. Downloading of files from FTP sites on the Internet is described in Section 3.5.1.
In addition to the standard ftp command, OpenVMS users on systems running TCP/IP software can use the alternative OpenVMS style commands to invoke FTP services and perform copy operations. On OpenVMS systems running TCP/IP software, the DCL command COPY/FTP invokes the FTP service and performs a copy operation (see Section 5.2.3).
The ftp command supports several file manipulation commands for managing remote directories. After establishing the FTP interactive session (as described in Section 3.3.1), the user can enter the ftp command dir or ls. This causes the remote system to list its directory contents on the local terminal. Other ftp commands provide directory operations such as creating, changing, or removing the remote directory and for other file operations over the TCP/IP network.
In addition to the standard ftp, dir, or ls commands, OpenVMS users on systems running TCP/IP software can use the alternative OpenVMS style commands to invoke FTP services that will list directories. On OpenVMS systems running TCP/IP software, the DCL command DIR/FTP invokes the FTP service and performs the directory listing operation (see Section 5.3.1).
The RCP application consists of an RCP client utility running on the local host and an RCP server on each remote host involved in the copy operation.
The rcp command copies one or more files from one host to another or copies whole directory trees. Some implementations of the rcp command permit the local user to copy files from one remote host to another.
The RCP server validates the rcp command from the local host by checking whether the source host name is in the destination host's database, or by resolving the IP address in the Domain Name System. Some products that implement the rcp command also use Kerberos authentication (see Section 5.1.1).
In addition to the standard rcp command, OpenVMS users on systems running TCP/IP software can use the alternative OpenVMS style commands to invoke RCP services that will perform copy operations. OpenVMS users on systems running TCP/IP software can use the DCL command COPY/RCP to invoke the RCP utility (see Section 5.2.4).
The Point-to-Point Protocol utility (PPPD) allows you to initiate and control a PPP connection from an OpenVMS Alpha host. With PPPD, you can:
OpenVMS users on systems running TCP/IP software can use the DCL command PPPD to invoke the PPP utility. PPPD commands allow users to set and display device characteristics; connect and disconnect a PPP session; and establish a connection with a new system. Chapter 6 describes the PPPD commands.
The Internet offers many resources for obtaining information from systems on the thousands of networks that form the Internet. Internet software tools are designed to operate over TCP/IP connections. These tools use many of the same client/server techniques as the common FTP and TELNET applications. In many instances, the tools for retrieving information are FTP and TELNET.
FTP provides an important service to Internet users by allowing them to move large quantities of data across the Internet. FTP sites on the Internet provide huge data storage facilities, storing files of all types. You can browse through the names and descriptions of files at FTP sites and download the files to your computer. Many files found on an FTP server are stored in a compressed format. When you receive a file, you can decompress (expand) the file to its original size.
Many sites permit you to log in as an anonymous user, which means you do not need a password. Anonymous FTP allows an organization to distribute certain files (for example, electronic magazines) for free to the general public.
The World Wide Web (WWW) is a client/server hypermedia system that runs over the Internet. Developed by CERN in Switzerland, + the WWW is an information management facility adopted by thousands of sites worldwide. Users access the WWW by pointing their client software at any of thousands of server connections. Hypertext multimedia documents stored in the WWW contain links to other data. The hypertext format allows you to retrieve and display data based on keyword searches.
Software tools called browsers are available to access data on the WWW. The Netscape Navigator browser is a hypertext interface to the WWW that has links to files, images, text, audio, and video. Netscape Navigator, which is a graphical, single-client application, offers point-and-click menus.
When you run the Netscape Navigator and connect to the WWW, the first display is usually a home page. The home page is specific to the site you selected and often contains a welcome message and hyperlink indicators. These indicators are highlighted phrases or graphics, which may be in color or underlined or both, that link to more specific information. By clicking on the hyperlinks, you can access data anywhere on the web.
For character-cell terminals, you can use the Lynx browser to interface with the WWW. Keyword links are highlighted on the screen. You can advance the cursor to a keyword and jump to the linked document residing anywhere on the web.
The Netscape Navigator is available on the Internet Product Suite CD. WWW tools and a WWW server are available on the Freeware CD.
The Gopher service is a client/server system that provides a simple, consistent means of accessing the full resources of the Internet. The Gopher is a highly automated software directory.
The Gopher client displays a series of menus from which you can make selections that the client carries out (for example, getting a file from a remote computer). Gopher menu items can lead to other menus at different sites.
Gopher servers are set up at many companies, universities, and other organizations to provide information of interest to local users. Many of the Gopher servers are public and supply information of interest to the general public. Gopher servers in many countries throughout the world are interconnected to form the Internet Gopher.
A Gopher client and server are available on the Freeware CD.
Once you are connected to the Internet, you can send electronic mail (or e-mail) messages over TCP/IP connections to systems throughout the Internet. You can also send mail to accounts that do not use Internet addressing; gateways translate the messages and send them to the appropriate networks and systems.
To send mail to an Internet address, use the format user@node.org according to the guidelines in the following list.
The format is also available in character-cell mail and DECwindows mail. For more information about the format for specifying Internet mailing addresses see the OpenVMS User's Manual.
Internet host computers may also maintain lists called "mailing lists," which are databases of people who have shared interests in a topic. Sending e-mail to the mailing list causes the mail to be sent to everyone on the list. Examples of messages include articles, comments, and other information about the topic of the mailing list. You can get on a mailing list by sending e-mail to the mailing list administrator. Some mailing lists have moderators who screen the messages for duplication and inappropriate content.
The UseNet protocol describes how to store and send groups of messages between computers that may or may not be on the Internet. UseNet (the User's Network) is a virtual forum divided into newsgroups that deal with various topics. The site administrator who sets up a newsgroup determines the topic of the newsgroup. Internet newsgroups are similar to notes conferences; they provide vast amounts of information.
You can use a UseNet reader software program to access a newsgroup. Discussions are conducted by sending e-mail messages to the newsgroup's address. If the newsgroup is moderated, the moderator screens the mail before posting it to the newsgroup.
A news reader, mxrn, is available on the Freeware CD.
http://info.cern.ch/hypertext/WWW/TheProject.html
TCP/IP networking applications support general user operations that access resources, such as files. One method of controlling who can access operating system resources is by assigning identification codes to users.
Both OpenVMS based systems and UNIX-based systems use identification codes as a general method of resource protection. However, each of the operating systems implement the coding differently. Because the TCP/IP software was originally developed on and used for UNIX machines, TCP/IP implementations use UNIX-style identification codes. Consequently, some TCP/IP applications must map UNIX identification codes to OpenVMS identification codes.
This chapter includes summary information about OpenVMS and UNIX identification codes and the mapping mechanisms used by TCP/IP applications.
OpenVMS users are familiar with the OpenVMS user identification code (UIC) that identifies the user as a member of a group that can share specific data. The UIC corresponds to the name of the user who created the process running on OpenVMS. The UIC is a 32-bit field comprising a 14-bit user number and a 14-bit group number. UIC-based protection controls access to such objects as files and directories.
Just as OpenVMS employs user names and UICs for identification, UNIX identifies users by user names and a user identification (UID) group identification (GID) pair. Both UIDs and GIDs are simply numbers that can identify a user on a system. Some versions of UNIX (for example, Digital UNIX) use 32-bit UID/GID pairs.
Some TCP/IP applications require use of UID/GID pairs for user identification. The most common application that requires this identification is the NFS (Network File System) client/server application. To use this application on OpenVMS, you must map OpenVMS user names to UNIX-style GID/UID pairs.
All TCP/IP vendors for OpenVMS support mechanisms for mapping OpenVMS user names to UID/GID pairs. Consult the appropriate vendor documentation for more information about how to manage this process for a particular OpenVMS TCP/IP layered product. (Appendix A lists TCP/IP layered products that run on OpenVMS.)
OpenVMS users can use familiar DCL commands, with special parameters and qualifiers, to log in, connect to a remote host over a TCP/IP connection, copy or transfer files from host to host, and display remote host directories on the local host. The local host and any remote hosts involved in these operations must be running one of the TCP/IP layered software products provided by one of the vendors listed in Appendix A.
This chapter describes the the COPY, DIRECTORY, and SET HOST DCL commands and their special parameters and qualifiers that support TCP/IP networking.
If you are a user on an OpenVMS client system running TCP/IP software, you can use SET HOST commands to access virtual terminal services, including:
This section presents the formats of the SET HOST commands supported over TCP/IP connections:
The SET HOST commands invoke the RLOGIN and TELNET client programs. A remote host is identified either by its Internet Protocol (IP) host name or by its IP address (see Chapter 2). See Section 3.2 for a description of the TCP/IP client/server applications that supply remote terminal services.
Kerberos authentication is a system that verifies the identity of users, thereby providing security in a network environment that otherwise may not be secure. Some TCP/IP software products use Kerberos to make sure the identity of any user who requests access to a remote host is authentic.
Kerberos keeps a control list of users and their encrypted passwords. Users must obtain Kerberos tickets to invoke utilities that support commands with special Kerberos enhancements. RCP, RLOGIN, and TELNET applications can support Kerberos enhancements.
When a TCP/IP layered product supports Kerberos authentication, a user on an OpenVMS system can specify the /AUTHENTICATE qualifier in any of the following OpenVMS DCL commands:
The DCL commands SET HOST/RLOGIN and COPY/RCP support the following three distinct case-sensitive forms of the /USERNAME qualifier value. Enclose the user name in quotes to preserve its case.
$ set host/rlogin/username=ralf host.dom
$ set host/rlogin/username="RaLf" host.dom
$ set host/rlogin/username="RALF" host.dom
This command logs the user in to a remote host over a TCP/IP connection and starts an interactive terminal session by accessing the RLOGIN application.
Format
SET HOST/RLOGIN
Parameters
Description
Qualifiers
Example
DCL> SET HOST/RLOGIN REMOTEHST1
This command connects you to a remote host over a TCP/IP connection by invoking the TELNET application.
Format
SET HOST/TELNET
Parameters
Description
Qualifiers
Example
DCL> SET HOST/TELNET remotehst2
This command connects your local host to a remote IBM host over a TCP/IP connection and invokes the TN3270 terminal emulator TELNET client program.
Format
SET HOST/TN3270
Parameters
Description
Qualifiers
Example
DCL> SET HOST/TN3270 REMOTEHST3
OpenVMS DCL commands support file manipulation utilities over TCP/IP connections, including:
The file access applications require a utility at the local terminal and one or more remote servers. See Section 3.3 for a description of remote file access utilities supported by TCP/IP.
The majority of files copied are ASCII text or binary images. These files are handled properly by all TCP/IP vendors' RCP or FTP applications. TCP/IP was written for UNIX systems, which use 512-byte blocks. OpenVMS, however, uses Record Management Services (RMS) as the native file system. RMS handles variable-length records and multiple file formats. Copying a file with any kind of record-oriented format to a UNIX system causes the file attributes to be lost.
Some of the TCP/IP products that run on OpenVMS (as described in Appendix A), allow copying of an FDL (file definition language) file so that OpenVMS can restore RMS file attributes retrieval. Most TCP/IP products on OpenVMS support special copying modes that preserve file attributes when files are copied to or from OpenVMS systems.
You can use OpenVMS DCL commands to access remote files over TCP/IP connections simply by including in the file specification the name of the remote host on which the file is located. You can access files that are protected against general access if the owner has provided you with the name and password of the account.
The OpenVMS DCL commands for TCP/IP support the same remote file specification format as the DCL commands for DECnet network connections. Some implementations of the file transaction applications support file transfers in which both the source file and the destination file are remote file specifications.
The full format for a remote file specification is as follows:
host"username password account"::remote-file-spec
If a file resides on a system other OpenVMS, enclose the name of the file in quotation marks. For example, to access a file named /usr/users/user/Orders on a Digital UNIX host named U32, you would use the following format for the file specification:
U32"user password"::"/usr/users/user/Orders"
6436P002.HTM OSSG Documentation 26-NOV-1996 11:22:26.17
Copyright © Digital Equipment Corporation 1996. All Rights Reserved.