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This chapter discusses basic features of an AppleTalk network and introduces the EtherShare network software. The modules that make up EtherShare are explained and hardware considerations when setting up a network are discussed.

Note: The chapters at the end of this manual describe in detail how to configure EtherShare by modifying the appropriate UNIX configuration files with a standard UNIX editor program such as vi. However, the EtherShare Admin program offers a much easier way to carry out EtherShare configuration and network management tasks.

The EtherShare Admin accesses and modifies the system configuration files directly, just as if the changes had been made with an editor. However, the EtherShare Admin has built-in safety checks to ensure that conflicting or invalid configuration settings are not possible.

In the following chapters, the distinction is often made between "logging on to EtherShare" and "logging on to the UNIX host". The latter is only necessary if you want to configure the EtherShare system manually instead of using the EtherShare Admin program, or if you want to access the UNIX host in order to develop or run software under the UNIX programming environment. This type of connection needs a conventional terminal (screen and keyboard), or a terminal program such as HELIOS Terminal, and means that you will need to be experienced in the UNIX operating conventions and utility programs, which are very different from those found on the Macintosh.

On the other hand, "logging on to EtherShare" is a routine task for any Macintosh user who needs access to the file server and print server facilities provided by EtherShare. Obviously, in this case too, the workstation is "logged-on" (or connected) to the UNIX host. Fortunately, EtherShare simulates the usual Macintosh environment in every way, as described in Apple's AppleShare manual, and users may not even be aware that they are linked to a UNIX-based computer rather than just another Macintosh.

The software which makes up EtherShare provides AppleShare server functions for Apple Macintosh (and DOS/ Windows-based) computers connected together in an AppleTalk network. Rather than running on an Apple Macintosh computer like conventional AppleShare servers, EtherShare is based on the powerful multitasking/multiuser features available under the UNIX operating system. Due to the availability of a large range of different UNIX-based computer systems of varying performance and price, with EtherShare, it is very easy to expand the power of your AppleTalk network at a later date, when the amount of work and the number of users increase.

EtherShare includes the EtherShare Admin program, which makes it very easy for the system administrator to configure the network. The EtherShare Admin can also be used by regular users to check the configuration. However, they are prevented from making any changes.

PCShare is a high-end TCP/IP-based file server, print server, and terminal server software for MS-DOS/Windows computers which are attached to UNIX computers through Ethernet, Token Ring, etc. Since PCShare is compatible with EtherShare, DOS/Windows users can share network printers and files with Macintosh and UNIX users, too.

The AppleTalk protocol stack forms the backbone for the EtherShare servers. It is responsible for basic AppleTalk network functions, including those of network routing. Routing means that EtherShare can be used to interconnect several physically separate AppleTalk networks, and transparently pass information between them as required.

While maintaining complete compatibility with the AFP specification, the EtherShare "File Server" program allows access to documents and applications throughout the whole network via high speed EtherTalk connections or via other connection such as FDDI, insofar as the interface is supported on the hardware being used.

With the help of an AppleShare 2.0 - 2.2 compatible client, you can also connect IBM-PC-compatible computers under MS-DOS (or PC-DOS) version 3.1 or later to EtherShare. EtherShare actively supports AppleShare connections from PC-compatible computers and even takes care of former MS-DOS file naming conventions. EtherShare can also be used to centrally store MS-DOS files and to access network printers from MS-DOS-based computers.

The following problem can arise when accessing Apple Macintosh files from an MS-DOS computer on the AppleTalk network: the Macintosh system allows up to 31 characters in the file name, whereas (old) MS-DOS file names are in upper case only and consist of a max. 8-character root file name and a max. 3-character extension separated by a period, e.g. "AAAABBBB.CCC". Furthermore, Macintosh file names can contain any of the displayable characters from the Macintosh character set, which is different from the character set of the IBM-PC.

To solve this problem, the EtherShare File Server automatically checks and translates file names when PCs access Macintosh files through AppleShare. Characters that cannot be displayed on the IBM-PC, or are disallowed in file names by DOS conventions, are replaced by the underline character "_" and/or a checksum, and PC characters that cannot be displayed on the Macintosh are replaced by a box character.

Another, much faster, way to network your UNIX host and thus your Macintosh computers with IBM-PC-compatible computers is to use HELIOS PCShare (see chapter A 11: "Glossary"). PCShare has its own built-in algorithm for dealing with long file names containing accented characters.

The EtherShare "Print Server" program ("papsrv") is a central spooler for print jobs destined for PostScript devices such as page printers (e.g. LaserWriter) and photo-typesetting machines (e.g. Linotype). The ImageWriter II, and ImageWriter LQ are also supported.

One or more printers can be connected to EtherShare simultaneously, either through, Ethertalk, TCP/IP, or connected directly to the UNIX host via a serial interface. Print jobs are received from the network and temporarily stored on the UNIX host before being sent to the assigned printer (print spooling). This considerably improves the throughput of the workstations on the network, since they can immediately dispatch their print jobs and do not have to wait for the printer. Other connection types are also supported (see chapter 11 "The Print Server").

Since EtherShare allows PostScript devices to be directly connected to the print server via a serial interface, it is not necessary for them to support Apple's "Printer Access Protocol" (PAP). The interface between such printers and AppleTalk networks is implemented in the Print Server, which allows such printers to be accessed from any workstation as if they were directly connected to AppleTalk. However, you may get problems with applications that send images as binary bitmap data, since serially connected PostScript printers interpret certain binary codes as control signals. Accordingly, we recommend AppleTalk, which is transparent to 8-bit data (see chapter 11.6 "Configuring printers manually"). Additionally, it is much faster than a serial connection, which is an important factor for images.

All printers (including those that support AppleTalk) should be driven through the Print Server, in order to take advantage of EtherShare's print job spooling feature - please select the corresponding printer queue from the Chooser and NOT the printer to which the queue is connected. This is especially important if you need to use different LaserWriter driver versions at the same time, since the Print Server will manage different "prep" file versions automatically without having to reset the printer each time.

In addition to printing to the assigned printer and providing spooling functions, the Print Server automatically interprets messages returned by the printer and forwards them to the appropriate user via electronic mail and "afpmsg". Apart from convenience, this feature allows rapid reaction to situations such as "paper out" or "paper misfed".

The various features of the Print Server are also available for MS-DOS workstations connected to the network via an AppleShare client or HELIOS PCShare. The "pstext" program which is provided (see paragraph below) can be used for printing DOS or UNIX text files on PostScript printers.

The text-to-PostScript converter "pstext" converts "flat" ASCII files to PostScript, to allow DOS and UNIX text filesto be printed on PostScript printers. It also allows you to print from DOS and UNIX applications which do not support PostScript. "pstext" has facilities for switching fonts and for "intelligent" semi-automatic pagination (see chapter 12 "Text-to-PostScript Converter").

The Macintosh program HELIOS Terminal allows workstations in the AppleTalk network to make one or more simultaneous connections to one or more UNIX hosts via a terminal emulation with multiple session capability. HELIOS Terminal communicates with UNIX through the Terminal Server.

The Macintosh program HELIOS Mail allows workstations in the AppleTalk network to send electronic mail messages and files to other Macintosh or UNIX users on the network. HELIOS Mail communicates with UNIX through the Mail Server. With the built-in TCP POP3 server in EtherShare 2.6, you can also use workstations other than Macintosh and mail programs other than HELIOS Mail with the EtherShare Mail Server.

HELIOS Mail offers an editor and an address book function. Incoming mail is received in the background and notified by a "Mail Notification Feature", which displays a dialog box including the Subject: and the New mail from: lines if you receive mail. You also receive EtherShare server messages, such as printer messages, via electronic mail. If you have a modem attached to the UNIX host and configured for UNIX mail (uucp), you can also communicate with several hundred thousand users of this worldwide e-mail system.

The Macintosh program EtherShare Admin makes it very easy for system administrators to configure EtherShare from one of the Macintosh workstations. It can also be used by regular users to check the configuration. However, they are prevented from making any changes.

EtherShare Admin communicates with EtherShare through the Administration Server. The Administration Server runs on the UNIX host while EtherShare Admin runs on the Macintosh workstations. The communication between these two programs takes place through a custom protocol derived from the AppleTalk Filing Protocol (AFP), which was especially developed by HELIOS Software GmbH for this purpose and is transparent to other AppleTalk devices, or via a TCP/IP connection which allows for managing multiple servers remotely and supporting concurrent AppleTalk and TCP/IP connections. (see via TCP/IP in chapter 5.3 "Logging on to the Administration Server").

The Desktop Server is responsible for storing icon and application data for the entire EtherShare server, and for managing file and directory IDs for network volumes.

Many of the functions of EtherShare are aided by the high performance of the UNIX operating system, and EtherShare is closely integrated with a number of the more common system programs and facilities in UNIX.

For example, EtherShare often uses the UNIX programs "lpr", "mail" and "syslogd". All three programs are responsible for passing information within the UNIX system itself, and are used by EtherShare mainly as a medium of transport.

"syslogd", which runs continuously in the background within UNIX, has the task of processing status and error messages from other active programs, and sending them to a specific output device or file in accordance with its configuration. All of the EtherShare modules use the services of "syslogd" to output system error messages and warnings.

By changing the configuration file "/etc/syslog.conf" on the UNIX server, the administrator is able to exactly control the flow of messages. For example, messages can be automatically passed on to users logged-on to the system (or entire groups), or simply stored in files or output to the system console.

With some operating systems, EtherShare (as many other UNIX programs) will not log any error messages or warnings unless "syslogd" has been appropriately configured.

"lpr", which is responsible for passing print jobs to the appropriate printer, is used by the EtherShare Print Server. "lpr" is configured through the UNIX configuration file "/etc/printcap". This file contains an entry for each printer queue assigned to the system in order to define how the printer is connected to the network, and to specify which programs are responsible for transferring data to the printer. The EtherShare Admin updates this file automatically whenever you change the printer configuration.

The Print Server is based on the BSD printing system. If your host uses the System V printing system (e.g. Sun Solaris 2.x), the Print Server automatically uses its own BSD-style "lpr" program, which is provided in the "$ESDIR" directory in such cases.

Under UNIX, the "mail" program is responsible for passing electronic mail messages between users or groups of users. Messages sent by the mail program to a particular user are stored on the host in the user's "mailbox". Either immediately, or at a later point in time, the user can call up "mail" to read the post. "mail" is also used by the EtherShare Print Server to pass printer status and error messages to the appropriate user.

Electronic mail is automatically sent directly to your Macintosh if you have installed our HELIOS Mail program. You no longer need to use the UNIX "mail" program to read it. Incoming mail is received in the background with a "Mail Notification Feature" which displays a dialog box including Subject: and the New mail from: line when you receive new mail.

Any user in the AppleTalk network who requires access to the EtherShare File Server must be entered as a UNIX user in the "/etc/passwd" file. The user must also be assigned a group in the "/etc/group" file. Note that the administrator can specify whether an AppleTalk user is permitted direct access to the UNIX host or not, in addition to EtherShare access. The EtherShare Admin updates these files automatically whenever you change users or groups.

The UNIX "passwd" program is used to assign passwords to users. The administrator can allocate new passwords, which are then automatically stored in the "/etc/passwd" file following encryption. The EtherShare Admin updates this file automatically whenever you change user passwords.

This file contains the commands that are automatically executed when starting (booting) the UNIX system (rc = run commands). The EtherShare installation program optionally inserts commands in this file to automatically start all of the EtherShare servers when UNIX is booted.

The UNIX program "mkdir" can be used to create new subdirectories in the UNIX file system. "mkdir" can also be used by the administrator to create new folders for the Macintosh. Please refer, however, to the notes contained in chapter 9.3 "Directory and file formats". Folders are best created or deleted by using the Finder from a Macintosh workstation. "rmdir" (remove directory) can be used to remove directories/folders when they are no longer needed.

The UNIX system program "chmod" (change mode) can be used to change user privileges for files and directories in the UNIX file system. You can also use "chmod" to change access privileges for Hierarchical File System (HFS) volumes created for Macintosh computers on the EtherShare File Server, although you should normally use the Macintosh program Sharing... (in the File menu) for this purpose. Please refer to chapters 9.3 "Directory and file formats" and 9.7 "Access privileges".

Important: You should never change the privileges of files in the EtherShare program directories, or in spool directories used by the EtherShare Print Server.

The UNIX programs "chown" and "chgrp" can be used to change the owner (creator) or group of a file or directory, although you should normally use the Macintosh program Sharing... (in the File menu) for this purpose. Only the system administrator can change the owner of a file or change the file's group to one in which the owner is not a member.

Important: For all of the commands mentioned above, we recommend to use the HELIOS Desktop utilities that belong to EtherShare 2.6. These utilities mimic the functionality of the UNIX commands "mkdir", "rmdir", "chmod", "chown", "chgrp", etc., while maintaining the integrity of the desktop database. The Desktop utlities are described in appendix A 9 "The Desktop utilities".

The UNIX program "cron" (cronos <Greek>= time ), which runs continuously within UNIX, can be configured to start and stop specified programs at predetermined times. An appropriate entry in the cron configuration table (crontab) can be used to start and stop a particular server at a specified time of day. "cron" can also be used to automate data backup procedures.

"ufsdump" is a data archiving program available on BSD UNIX systems. It is the recommended program for making backup (security) copies of network volumes to a tape streamer or other removable storage media attached to
the UNIX host. You can read in the archive again with
"restore". See chapter 9.8 "Data backup" and appendix
A 6: "Data backup with "dump" and "restore"".

There are several different ways of connecting workstations and printers together to build a network. If you want to build e.g. an Ethernet or FDDI network you may have to install appropriate interface cards in some or all of the workstations and servers.

AppleTalk is a generic name used by Apple for all types of Apple-compliant network connections. EtherTalk is the name Apple gives to the AppleTalk protocol when it is used on an Ethernet network. TokenTalk is the name Apple gives to the AppleTalk protocol when it is used on an IBM Token Ring network. AppleTalk is not "compatible" with TCP/IP, but can co-exist with TCP/IP (and other network protocols) on the same network cable without mutual interference. Under EtherShare, the same host network card is often used for TCP/IP and AppleTalk simultaneously.

Ethernet is a hardware and network protocol standard which has found worldwide acceptance by a large number of computer manufacturers. Ethernet (EtherTalk) interface cards are available for most Macintosh computers, high-end Apple printers, and all UNIX hosts. Many UNIX hosts and some newer Macintosh computers have an Ethernet interface already built in.

IBM Token Ring is a hardware and network protocol standard which is supported by many types of IBM computers including IBM mainframes and the RS/6000 workstation. Token Ring (TokenTalk) interface cards are available for most Macintosh computers. A Token Ring card can be plugged into the IBM RS/6000 workstation to allow it to be used as an EtherShare host.

If you have two or more different network types in the same building (e.g. Ethernet and FDDI) you may already have installed an AppleTalk router box to interconnect them. Alternatively, you may be using a software router (e.g. the AppleTalk Internet Router), which operates in the background in one of the Macintosh workstations.

EtherShare has automatic built-in routing functions. Whereas the EtherShare routing system can co-exist quite happily with other routers in the network, it might be worthwhile re-arranging your network to route with EtherShare instead, since this will give you significantly better performance than software routers.

The various junctions, routers, bridges and devices in the network are called nodes, and the way that they are physically connected together is called the topology of the network. On the one hand, the topology is dependent on usage requirements (the required position of the workstations within an office building). On the other hand, it is also necessary to take account of physical limitations imposed by the chosen hardware (e.g. maximum cable lengths) and by network standards.

Ethernet is logically characterized by a linear bus topology. However, nowadays the 10Base-T Ethernet and 100Base-T Ethernet - also called Fast Ethernet - have, from the physical point of view, a star-shaped topology. This means that all workstations and printers etc. connected to the network are attached to a hub in the logical center of the "star". Token Ring is, physically seen, also star system, with active hubs ("amplifiers") at the center of each star. The "ring" is only virtual - the "token" packet is passed in a pre-defined sequence from one workstation to the next.

When installing the network cable, it is important to make sure that it is not installed with sharp bends or under tension. It should be laid in such a way that it cannot be damaged, and it should be routed as far away as possible from powerful electrical fields. Please observe the exact specifications of the hardware manufacturer. The manufacturer's documentation contains all required information on admissible cable lengths, types of connectors to be used and other points to be noted.

The AppleTalk protocol allows a number of physically separated networks to be linked together. The separate networks can use either the same or different hardware standards. The connection between two networks is implemented with so-called routers. The special software that runs in routers is called router software.

Each separate network is assigned a unique network number. A zone is a group of one or more logical networks with the same symbolic (logical) name. A device in the network is a member of a particular zone. However, a router between two networks (e.g. between FDDI and EtherTalk) is a member of at least two logical networks. Furthermore, in some cases two logical networks can co-exist on the same hardware cable (provided, of course, that they use the same hardware standard).

Under AppleTalk Phase II - in contrast to the outdated AppleTalk Phase I - one cable can support several logical networks, and a zone can contain more than one network, provided that the set of network numbers constitutes a continuous range (e.g. 101-108). Furthermore, several zones can co-exist on the same cable. There is a limit of 254 nodes per sub-network (section), but it is possible to have a larger number of devices per network. This became necessary when very large Ethernet networks started to appear.

Note that some new features were not included in the first release of EtherShare 2.6, but have been added by means of an update. Updates are published on our Web server www.helios.de and on our distribution CD-ROMs. They are released to make fixes or new features available.

The MachID is now a 8-2 digit hexadecimal string with the last two digits representing the make and model of your host computer. The MachID is required to request the software activation key.

EtherShare 2.6 is the base software for our powerful extensions EtherShare OPI 2.1, PDF Handshake, and Print Preview. Note that EtherShare 2.6 does not support our old EtherShare OPI 1.2.

The EtherShare Macintosh applications for client computers - e.g. EtherShare Admin and HELIOS Mail - can now be installed more easily, using the new "EtherShare Client Installer".

AFP servers were traditionally only available in local area networks. The new AFP over IP transport allows connections to the AFP server from anywhere on the Internet. To protect your site, you might want to create an IP access list to restrict access to your server. You can create such a list on your UNIX server, but it is much easier to use the EtherShare Admin program instead. It offers all options that are required for a standard access control.

EtherShare 2.6 contains a "Fast" Finder copy as available in AppleShare Workstation 3.6. This Finder is able to create and handle large data packages and thus is much faster than previous Finder copies.

You may now search files by name on the server within a reasonable period of time, namely within a few seconds. With former software versions "Find File by Name" sometimes took a few minutes or even longer.

File locking has been improved for AFP volumes. For details, please refer to the explanations File and record locking in chapter 9.3 "Directory and file formats".

With EtherShare 2.6 you can send short "AFP" messages to any connected client provided that EtherShare is running. These messages can be sent from the UNIX server using the UNIX "afpmsg" program, or from a Macintosh client using the EtherShare Admin program.

The new "netconf" program has been improved considerably as far as the automation of processes is concerned. The program also comes with an enhanced user interface.

Our new "vpoll" UNIX program follows the former "poll" program. The program serves to list and check network devices and entities. "vpoll" is an interactive program. It behaves similar to the Apple program "InterPoll".

The new EtherShare 2.6 supports administration over AppleTalk and TCP/IP. This allows to manage multiple servers remotely via TCP/IP connection, and additionally supports concurrent TCP/IP and AppleTalk connections.

We have implemented two new items in the Admin's Printer menu. They allow to choose the desired PPD file for each printer queue, and to display the contents of the PPD file that is currently selected.

You can define hold and/or error queues with the new Admin and automatically direct print jobs into one of these queues after they have been processed. The jobs are stored in the hold or error queue for a given period of time and can easily be restarted without the need to open the original application again.

With EtherShare 2.6, you can set up a group of printers for load balancing that is for shifting print jobs to a second or third printer in a group whenever the other printers are busy with a huge job.

There are now two different printer administration groups, namely "PrnAdm" and "QueueAdm". One group is only allowed to manipulate print jobs, the other one (the "QueueAdm" group) is allowed to change the configuration of printer queues.

The organization of log files has changed. They are now arranged by date and deleted automatically after seven days. Furthermore, EtherShare 2.6 log files contain extended information. Printer log files e.g. state the total number of bytes printed and indicate whether you have printed composite or separations.

The Versions window provides several information about the program versions of the various Macintosh and UNIX programs that are installed on your system. With EtherShare 2.6 this window additionally contains information about your EtherShare, interface, and syslog configuration.

The EtherShare 2.6 software package contains the HELIOS LanTest version 2.5. This LanTest software is able to measure transfer rates during printing and lets you switch between two different file sizes, namely 3 MB (recommended for testing standard Ethernet networks) and 30 MB (recommended for testing FastEthernet or FDDI networks).

The HELIOS Desktop utilities allow to manipulate Macintosh files under Unix in a way that Macintosh resource information are left intact. The main UNIX commands for handling files incl. "rm", "mv", "cp", "ls", "mkdir", "touch", "chmod", "chown", and "chgrp" are enhanced by these utilities. Thus, the utilities will turn out to be a helpful tool for system integrators, experienced EtherShare users, and developers. See appendix A 9: "The Desktop utilities" for more details.

HELIOS EtherShare 2.6 User manual