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This chapter introduces the PCShare network software, discusses network hardware and topology, and finally describes the new features of the program version 3.

The PCShare 3 services allow connected Windows clients to access documents and printers, and are fully compatible with standard Windows programs, including multiuser applications. PCShare 3 integrates powerful servers into Windows networks so that drives and printers can be mounted via the Windows network browser.

The PCShare built-in DHCP/BOOTP server allows automatic distribution of TCP/IP configurations to any Windows, Macintosh or other devices connected to a server network port. With the DHCP backup server capability all DHCP/BOOTP clients will continue to work if the main server fails. Remote Windows PCs can be integrated via WINS.

The TCP/IP protocol stack forms the backbone for the PCShare services. It is responsible for basic TCP/IP network functions, including those of network routing, which means that PCShare can be used to interconnect several physically separate TCP/IP networks, and transparently pass information between them as required.

The menu-driven PCShare Admin supports an easy setup of users, groups, volumes, printers, and DHCP from any Windows or UNIX system on the network. It also displays server and printer log files, system messages, program versions, server and PC activities, and offers the possibility of sending messages from any UNIX or Windows system on the network.

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

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

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

PCShare also accesses the UNIX system files "/etc/passwd", "/etc/group", "/etc/printcap" and "/etc/rc.local" (or on System V machines "/etc/inittab" respectively).

"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 PCShare 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, PCShare (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 PCShare print server. "lpr" is configured through "/etc/printcap", the UNIX configuration file. 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 PCShare Admin updates this file automatically whenever you change the printer configuration.

The PCShare print server is based on the BSD printing system. If your host uses the System V printing system (e.g. Sun Solaris 2.x), PCShare automatically uses its own BSD-style "lpr" program, which is always provided in the "$PCDIR" directory.

Any user in the TCP/IP network who requires access to the PCShare 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 TCP/IP user is permitted direct access to the UNIX host or not, in addition to PCShare access. The PCShare 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 PCShare 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 PCShare installation program optionally inserts commands in this file to automatically start all of the PCShare servers when UNIX is booted.

Important: If you have HELIOS EtherShare installed on the same server you must use its "dt" utilities (e.g. dt mkdir,
dt rmdir, etc.) instead of the following UNIX programs.

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 directories/folders for the PC. Folders are best created or deleted by using
File > New > Folder (or File > Delete, respectively) on a Windows 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 files/folders created for PCs on the PCShare file server.

Important: You should never change the privileges of files in the PCShare program directories, or in spool directories used by the PCShare print server.

The UNIX programs "chown" and "chgrp" can be used to change the owner (creator) or group of a file or directory. 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.

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.

"dump" 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 the "restore" command.

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.

Ethernet is a hardware and network protocol standard which has found worldwide acceptance by a large number of computer manufacturers. Ethernet interface cards are available for most Windows computers, high-end printers, and all UNIX hosts. Many UNIX hosts and some newer Windows 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 interface cards are available for most Windows computers. A Token Ring card can be plugged into the IBM RS/6000 workstation to allow it to be used as a PCShare host.
Due to high-performing Ethernet networks, Token Ring is nowadays rarely used.

The various junctions, routers, bridges and devices on the network are called nodes, and the way 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 a star -shaped 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 TCP/IP 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 workgroup is a group of one or more logical networks with the same symbolic (logical) name. A device on the network is a member of a particular workgroup. However, a router between two networks (e.g. between FDDI and Token Ring) 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).

Note that some new features were not included in the first release of PCShare 3, 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 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.

If a volume is available for both EtherShare and PCShare server, PCShare 3 will now use the EtherShare desktop database as well. PCShare 3 also co-operates with EtherShare OPI 2.1 (in this case you need to have installed EtherShare 2.6. on your server, as well).

Beneath "system administrators" and "printer administrators" PCShare now offers the new group "queue administrators" whose members can use the PCShare Admin to manipulate print jobs and queue configurations. Thus, they have even more privileges than members of the "printer administrators".

With PCShare 3 you can send short messages to any connected Windows NT4/2000 client (for Windows 95/98/Me the WinPopup program must be running). These messages can be sent from the UNIX server using the UNIX "pcsmsg" program.

The PCShare Admin > Statistics > Program Versions window provides various information about the program versions of the various PCShare programs that are installed on your system. Additionally it contains information about your PCShare, interface, and IP-access configuration.


HELIOS PCShare 3.0 User manual

HELIOS PCShare 3.0 User manual