Document revision date: 19 July 1999

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.

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.

4.1 What Are UIDs and GIDs?

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.

4.2 Establishing the Relationship Between UID/GID Pairs and OpenVMS User Names

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.

5.1 Remote Terminal Services

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:

• Logging in to a remote system using the RLOGIN utility
• Connecting to a remote system using the TELNET service, including connecting to an IBM system using the TN3270 terminal emulator

This section presents the formats of the SET HOST commands supported over TCP/IP connections:

• SET HOST/RLOGIN
• SET HOST/TELNET
• SET HOST/TN3270

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.

5.1.1 Kerberos Authentication

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:

• SET HOST/RLOGIN
• SET HOST/TELNET
• SET HOST/TN3270
• COPY/RCP

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.

1. Normally, the username is all lowercase characters:

   $ set host/rlogin/username=ralf host.dom

2. The username can contain mixed-case characters:

   $ set host/rlogin/username="RaLf" host.dom

3. The username can contain all uppercase characters:

   $ 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

• IPhostname
• IPaddress

Parameters

• IPhostname
  Specifies the IP host name of the remote host.
  
• IPaddress
  Specifies the IP address of the remote host.

Description

• The SET HOST/RLOGIN command allows you to log in to a remote host. The command invokes RLOGIN client software that runs on your system. After the terminal session starts, you can enter commands interactively on the remote host. The parameter that specifies the remote host is either an IP host name or an IP address. The /RLOGIN qualifier is a required part of the format. Other available qualifiers are in the following list.

Qualifiers

• /AUTHENTICATE
  Specifies that Kerberos authentication should be used for acquiring access to the remote host.
  
• /PASSWORD=password
  Optional qualifier that specifies the password of the user who is logging in to the remote host.
  
• /TERMINAL_TYPE=type
  Sets the terminal emulator to one of the following terminal types: VT100, VT200, VT300, VT400, VT500.
  
• /TRUNCATE_USERNAME
  Specifies that the current user name must be truncated to 8 characters before attempting to connect to the remote host. The qualifier is required for communication with systems that limit the size of their login names to 8 characters. The /TRUNCATE_USERNAME qualifier is ignored if /USERNAME is specified.
  
• /USERNAME=username
  Specifies the user name for logging in to the remote host. The user name can be enclosed in quotes to preserve the case of the user name for case-sensitive systems such as UNIX (see Section 5.1.2). If the /USERNAME qualifier is not specified, the default is the current user's name.

Example

DCL> SET HOST/RLOGIN REMOTEHST1

• This example creates an RLOGIN connection to remote host REMOTEHST1 over a TCP/IP connection.

This command connects you to a remote host over a TCP/IP connection by invoking the TELNET application.

Format

SET HOST/TELNET

• IPhostname
• IPaddress

Parameters

• IPhostname
  Specifies the name of a remote IP host.
  
• IPaddress
  Specifies the IP address.

Description

• The SET HOST/TELNET command allows you to connect to a server on a remote system by invoking the TELNET client software that runs on your system. The parameter that specifies the remote host is either an IP host name or an IP address. Most of the attributes are negotiated with the remote host. The qualifiers are used only in exception cases (for example, cases where a remote server does not support a negotiated parameter but requires a certain characteristic for the connection). The /TELNET qualifier is required in the format. Other available qualifiers are in the following list.

Qualifiers

• /AUTHENTICATE
  Specifies that Kerberos authentication should be used for acquiring access to the remote host.
  
• /PORT=port
  Specifies the remote TCP port to use. The default is 23.
  
• /TERMINAL_TYPE=type
  Sets the terminal emulator to one of the following terminal types: VT100, VT200, VT300, VT400, VT500.

Example

DCL> SET HOST/TELNET remotehst2

• This example creates a TELNET connection to remote host remotehst2 over a TCP/IP connection.

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

• IPhostname
• IPaddress

Parameters

• IPhostname
  Specifies the name of an IP host.
  
• IPaddress
  Specifies an IP address.

Description

• The SET HOST/TN3270 command makes a connection with a TELNET server on a remote IBM system and invokes the TN3270 terminal emulator TELNET client program on the local host. The parameter that specifies the remote host is either an IP host name or an IP address. The TN3270 client automatically determines the terminal type (IBM-3278-2, IBM-3278-3, IBM-3278-4, or IBM-32798-5). The /TN3270 qualifier, which is required in the format, causes the local keyboard to emulate an IBM 3279 class terminal keyboard by invoking the TN3270 terminal emulator. Other available qualifiers are in the following list.

Qualifiers

• /AUTHENTICATE
  Specifies that Kerberos authentication should be used for acquiring access to the remote host.
  
• /PORT=port
  Specifies the remote TCP port to use. The default is 23.

Example

DCL> SET HOST/TN3270 REMOTEHST3

• This example creates a connection to a TELNET server on the remote IBM system REMOTEHST3 over a TCP/IP connection.

OpenVMS DCL commands support file manipulation utilities over TCP/IP connections, including:

• FTP, which transfers files between hosts
• RCP, which permits files to be copied from host to host

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.

5.2.1 File Length and File Format

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.

5.2.2 Remote File Specification Format

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"

Unlike OpenVMS, UNIX systems support case-sensitive file specifications.

(See also Section 5.1.2 for a description of case-sensitive user names.)

5.2.3 COPY/FTP

Format

COPY/FTP from-file to-file

Parameters

• from-file
  Specifies the name of an existing file (the source file) to be copied.
  
• to-file
  Specifies the name of the output file (the destination file) into which the input file is copied.

Description

• The COPY/FTP command copies files to and from remote hosts using the File Transfer Protocol (FTP). The services provided by this command are a subset of the architected features of FTP. (See the vendor documentation for usage of their supplied FTP program.) The /FTP qualifier is required in the format. Other available qualifiers are in the following list.

  Note In OpenVMS to OpenVMS transfers, if both machines support VMS structured transfers, the /BINARY, /ASCII, and /FDL qualifiers are ignored. The cooperating OpenVMS FTP client and server automatically transfer the file with proper OpenVMS attributes.

Qualifiers

• /ANONYMOUS
  Causes an anonymous access to the remote host or hosts. /ANONYMOUS is the default remote access. The password passed to the remote host must have the form user@fully-qualified-host-name.
  
• /ASCII
  Identifies an ASCII text file. /ASCII is the default.
  
• /BINARY
  Identifies binary files.
  
• /FDL
  Causes interaction with an FDL (file definition language) file. If the file is being copied to the local OpenVMS system, a remote FDL file is sought and interpreted for the operation. If the file is being copied outside the local OpenVMS system, an FDL file is generated and copied in addition to the requested file. If the /FDL qualifier is specified and the vendor application does not support it, a warning message may be issued. This qualifier is optional.
  
• /LOG
  Displays a message at SYS$OUTPUT when a file is transferred.
  
• /NOSTRUVMS
  Explicitly disables the negotiation of STRUVMS transfers. Otherwise, some servers will immediately abort when negotiating the feature.
  
• /VERBOSE
  /NOVERBOSE
  Specifies whether all messages (including banner messages) are to be displayed on the terminal. By default, disables the display of the messages.

Examples

DCL> COPY/FTP/ASCII/ANON ovms_file1.c remotehst5::"/public/ovms_file2.c"

• This example transfers the local text file OVMS_FILE.C to the remote file /public/ovms_file2.c on remotehst5 using anonymous access over a TCP/IP connection.

DCL> COPY/FTP/FDL/ANON rms_indexed_file.idx remotehst5::"/public/rms.idx.file"

• This example transfers the OpenVMS RMS file RMS_INDEXED_FILE.IDX to the remote file PUBLIC/RMS.IDX.FILE on REMOTEHST5 over a TCP/IP connection. The access to the remote host is anonymous; an FDL file is generated and copied along with RMS_INDEXED_FILE.IDX.

This command copies files from host to host over a TCP/IP connection by invoking the RCP utility.

Format

COPY/RCP from-file to-file

Parameters

• from-file
  Specifies the name of an existing file (the source file) to be copied.
  
• to-file
  Specifies the name of the output file (the destination file) into which the input file is copied.

Description

• The COPY/RCP command copies one or more files (or directory trees) to or from a remote host using the RCP utility.
  The file specification format is described in Section 5.2.2.
  The /RCP qualifier, which automatically recognizes binary and ASCII formats, is required in the format. Other available qualifiers are in the following list.

Qualifiers

• /LOG
  Displays a message at SYS$OUTPUT when a file is transferred.
  
• /PRESERVE
  Preserves the file protection codes.
  
• /RECURSIVE
  Requests a subdirectory copy operation.
  
• /TRUNCATE=USERNAME
  Truncates the user name to 8 characters.
  
• /USERNAME=username
  Optional qualifier that specifies the remote user name. The standard operation is to log in to a remote system using the same user name as at the local terminal. The command supports quoted parameters in the /USERNAME value (see Section 5.1.2).

Example

DCL> COPY/RCP local_file.c remotehst4"Smith smpw"::rem_file.c

• This example copies LOCAL_FILE.C to REM_FILE.C on the remote host REMOTEHST4 over a TCP/IP connection.

FTP applications support commands to manage the directory to or from which you are transferring files. The DCL command DIR/FTP gets a list of the contents of the remote directory. Section 3.3.2 describes how to use FTP in listing remote directories.

5.3.1 DIR/FTP

This command displays remote directory information over a TCP/IP connection by invoking the FTP utility.

Format

DIR/FTP directory-spec

Parameters

• directory-spec
  Specifies the standard DECnet remote file specification. A quoted file string preserves the case (for case-sensitive systems such as UNIX) and identifies a foreign device and directory specification (see Section 5.2.2).

Description

• The DIR/FTP command writes a listing of the contents of the specified remote directory to the local host over a TCP/IP connection by invoking the FTP utility. The /FTP qualifier is required in the format. Other available qualifiers are in the following list.

Qualifiers

• /ANONYMOUS
  Causes an anonymous access to the remote host or hosts. /ANONYMOUS is the default remote access. The password passed to the remote host must have the form user@fully-qualified-host-name.
  
• /FULL
  Displays additional information about the files in the specified remote directory if the /FULL qualifier is supported by the remote server.

Example

DCL> DIR/FTP remotehst6"Jones jpw"::"usr/public"

• This example causes the contents of the remote directory USR/PUBLIC on remote host REMOTEHST6 to be displayed at the local host over a TCP/IP connection.

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