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COMPUTERS: Networking for the home or small office Beyond The Basic Network Setting up a LAN using TCP/IP Are you getting the best out of your current PC? You can get even more out of it by networking it to one of your older PCs which can then be used as a print server or fax server while you carry on with other tasks. By BOB DYBALL Not too long ago, a “LAN” or “Local Area Network” meant having an expensive server and a number of dumb terminals. Although it can still mean this, a LAN is now usually a “peer to peer” network, consisting of two or 8  Silicon Chip more PCs which can act as both servers and clients. A server no longer has to be expensive either. In fact, you can use a previously retired 386 or 486 machine for many tasks, thereby freeing your main PC for more useful jobs. Whether you are in a small office or just at home, take a look at what networking can do for you. For example, a LAN will allow you to: •  share a printer; •  share files or programs; •  share a modem for fax or Internet access; •  set up a small web server and Intranet; •  study networking to further your education; and •  play games against other family members and friends. Obviously there are many different things that you can do but where should you start? The first thing to do is take a look at your needs and the resources you have available. For example, let’s say that you have a small office with three or four people and you’ve recently upgraded your last remaining 486 PC to a Pentium machine. Before tossing the old 486 onto the scrapheap, consider putting it to use as say a fax server and printer server. That way, everyone in the office can easily print to the same printer and have access to a modem, provided that they’re part of the network. On the home front, you may have a laptop that’s used for work plus a fairly new PC that’s used by the kids. In addition, you may also have an old 386 machine that’s been retired, or you know where to acquire one quite cheaply. Now here’s the problem: both you and the children need to get onto the net but you’d like to avoid having extra phone lines (and modems). You are also concerned about what they might see on the net. A LAN can help here and, with the right software, pro­vide a “gateway” to the net that is safe and convenient. And you will only need one modem for everyone. Setting up a LAN involves installing a network card in each PC involved. For a laptop, the network card might be a plug-in PCMCIA or PC card device, while for older PCs it will be a 16-bit ISA network card. Pentium or later machines can be fitted with either ISA or PCI network cards. Networking options Two main types of LANs are commonly used in small “peer to peer” systems. The cheapest to set up is known as 10Base2. It uses RG-58 coaxial cable and network cards that have BNC connec­tors fitted. The PCs are simply connected together in daisy-chain fashion (see Fig.1), with the cable run via T-connectors on each PC. The two ends of the chain are fitted with 50-ohm terminators. The other common system is known as 10BaseT. This type of system requires a “hub”, which provides a central connection point for the network – see Fig.2. It uses flat twisted-pair cable fitted at either end with RJ-45 connectors (similar to telephone connectors). A hub costs $50 or more for a small 5-port model but you can also buy 8-port and 16-port hubs if required. Be- Fig.1: a 10Base2 (thin Ethernet) network uses coaxial cable and network cards that have BNC connec­tors fitted. The PCs are connected together in daisy-chain fashion, with the cable run via T-connectors on each PC. The two ends of the chain are fitted with 50-ohm terminators. Fig.2 the 10BaseT system requires a “hub”, which provides a central connection point for the network. It uses flat twisted-pair cable fitted at either end with RJ-45 connectors (similar to telephone connectors). cause a hub is not needed for 10Base2, many home users opt for this type of network. It’s cheaper but a break anywhere in the cable usually means that the whole network stops working. In an office, where reliability is more important, the 10BaseT network is often used. It’s advantage is that one faulty cable, say from one user to the hub, doesn’t bring the whole network down. Only the user with the faulty cable will be affect­ed. A look at the diagram for 10Base2 (Fig.1) shows why a single break in the cable can affect everyone on the network. Occasionally, users in each of the remaining segments of cable can “talk” to each other but the absence of a terminator at one end of the cable segment makes this very unlikely. If you do decide to use 10Base2, look for a “combo” net­work card. These have both 10BaseT and 10Base2 connectors. This will allow you to change to a 10BaseT network later on, if you Table 1: 10Base2 vs. 10BaseT 10B ase2 Advantages Disadvantages Generally cheaper to set up. A cable break anywhere generally brings down the whole network. Ideal for use where Inconvenient to users are spread install where users out i n a l i ne. are in a "star" arrangement. Slower than 10BaseT, since network cards are limited to halfduplex operation. 10B aseT Advantages Disadvantages More reliable - a break in a cable affects only one user. Ideal for use where users are clustered together in one area and the hub can be centrally located. Faster than 10Base2 since the network cards can use full duplex operation. More expensive because a central hub is needed to connect all users. Messy and expensive to cable where the users are all located in a l ong l i ne. November 1998  9 Add button, select Protocol, click Add again, select Microsoft, select TCP/IP and click OK – see Fig.3. Once you have installed the networking protocol(s), select the TCP/IP protocol for your network card (at the Configuration tab of the Network applet) and click the Properties button. You can now set up your IP address, as shown in Fig.4. Note that the IP address set here is “bound” to the LAN card and is non-routable. In other words, it is purposely select­ed so that it is ignored if you connect to the real Internet, in the outside world. IP addresses Fig.3: check this dialog box to ensure that the TCP/IP protocol is installed for your network card (not just for a DialUp Adapter). If it hasn’t been installed, follow the procedure in the text. Fig.4: you set up the TCP/IP addresses using this dialog box. Each computer on the network must have its own address and these must also be entered in a simple text file named LMHOSTS – see text. wish to expand the network. In fact, it’s difficult to buy straight 10Base2 network cards these days. PCMCIA cards for laptops tend to be a rather expensive. However, you should be able to get a reasonable PCI or ISA combo network card for less than $40.00 set up your own intra­net and experiment with a web server, then you will have to use the TCP/IP networking protocol. In case you’re wondering, TCP/IP stands for “Transmission Control Protocol/Internet Protocol” and was originally devised by Novell. Although it might initially appear rather mysterious, TCP/IP isn’t all that hard to get going. The first step is to install the networking protocol and you do that via the Network applet in Control Panel. The procedure is as follows: load the applet, click the NOS: Network Operating System Prior to Windows for Workgroups 3.11, you didn’t have too many choices when it came to the network operating system (NOS). You either used Lantastic or Novell Personal Netware for a “peer-to-peer” system, or you used a Novell server in a client/server arrangement. None of these choices were cheap and nor were they all that easy to set up. This situation changed with Windows for Workgroups 3.11, which featured an inbuilt peer-to-peer network operating system (NOS). Windows 95/98 and Windows NT also include built-in network­ing capabilities. Identification Network protocols Usually, you would set up a small network using either the NetBEUI or IPX/SPX protocols. Indeed, if you intend using your old PC up as a file server, print server and/or a fax server, these network protocols are likely all you’ll need. On the other hand, if you’d like to 10  Silicon Chip How do you know which number you can use. Well, the Inter­net Assigned Numbers Authority (IANA) has reserved the following three blocks of the IP address space for “private internets” (ie, intranets): (1) 10.0.0.0 to 10.255.255.255 (2) 172.16.0.0 to 172.31.255.255 (3) 192.168.0.0 to 192.168.255.255 For this and further details on IP addressing, see refer­ence document RFC1918 at: http://ucnet.canberra.edu.au/RFC/ rfc/rfc1918.html The special IP address 127.0.0.1 refers to the PC itself. This is useful to know in some cases; eg, if you have a program that uses TCP/IP to “talk” to another program on the same PC. Because these TCP/IP addresses are non-routable, it means that the Internet can not normally “see” past the PC that has the modem. In other words, it cannot “see” the other computers on the network (unless you have special software acting as a go-between). Nor can the rest of your intranet normally access the Internet through the PC with the modem. Of course, there are ways to provide this access and this involves using a “gateway” or “router”. Fig.5: each computer on the network must be given a unique Computer name but all machines must have the same Workgroup name. Having set up the IP addresses, you need to uniquely identify each computer on the network. You do that by clicking the Identification tab at Fig.3 to bring up the dialog box shown in Fig.5. Each computer must be given a unique “Computer name” but the same Workgroup name must be used for all machines on the network. Having done this, click the “File and Print Sharing” button and select Fig.5: Example LMHOSTS File 192.168.0.10   Anne 192.168.0.20   John 192.168.0.30   Server 192.168.0.40   Workstation whether you wish to share your files and/or a printer. Road maps for TCP/IP: LMHOSTS & DNS In simple terms, packets of information sent via the Inter­ net using TCP/IP find their way around using a Domain Name Server (DNS). These are like road maps. Usually, it’s not worth the trouble setting up a DNS to translate names to IP addresses for a small intranet (and in any case, you need NT Server). Instead, on a small network, IP addresses are best allocated using a simple text file called LMHOSTS. On large networks with NT Server, you can use WINS or DHCP. The LMHOSTS file contains a list of the names of the various PCs on the intranet and their corresponding IP addresses. A sample file called LMHOSTS.SAM should be in the C:\ WINDOWS directory. You simply copy this to the filename LMHOSTS in the same directory, strip out the comments (for speed of access by the PC) and edit it to include the details of the PCs in your system. When the PC is restarted, your software will be able to “see” other PCs on the network (programs permitting) which use the TCP/IP protocol. The accompanying panel (Fig.6) shows an example LMHOSTS text file after editing. Note that the various names must agree with the names assigned to each computer – see Fig.5. Having set up your TCP/IP network, you can put it to work. Let’s take a closer look at some of the more useful functions. File server It is much simpler to back up one directory than many direc­tories on different PCs. Storing your documents on a shared directory on a network drive means that you need only back up one directory branch to save copies of everyone’s work. If you have invested in a ZIP drive or CD-ROM writer, this can be cen- Fig.7: you can share a drive (or folder) by right clicking it in the Explorer, then clicking the Sharing option from the drop-down list and selecting the various options in this dialog box. Fig.8: to share a printer, double click printers in My Computer or in the Control Panel (of the print server), right click the printer and select the Sharing tab. trally placed to allow easy backup and access. To share a drive, right click it in the Explorer (or in My Computer), click Sharing and click the “Shared As” option – see Fig.7. Type in the share name in the space provided, then click “Full” for the Access Type. You can also set a password if you wish but don’t do this unless necessary because it can be a nuisance. Windows 98. You will need to get a third party product, such as I-Share from Artisoft, if you wish to share a modem across the network. Print server Sharing a printer is just as easy as sharing files across the network. Under Windows 95 or 98, on the printer “server”, click Start, Settings, Control Panel, then double click Printers. Now right click the printer, select the Sharing tab and you’re all but there – see Fig.8. Shared modem access Unfortunately, sharing a modem (eg, for bulletin board access) is not something that’s built into Windows for Workgroups 3.11, Windows 95 or Fig.9: don’t forget to click the “File and Print Sharing” button so that you can share your files and/or printers. Shared Internet access Unfortunately, you also need extra software to provide shared Internet access across a network using one dial-up modem – unless you have one of the big guns, that is (eg, Windows NT4 Server or Microsoft Proxy Server 2.0). However, this isn’t difficult if you have the right program. There are a number of commercial packages for Windows and these fall into one of two categories. Some programs simply act as “routers”, re-routing Internet traffic appropriately. Others have a complete firewall system built in, including password access, and may even include a “proxy server” to cache web pages already recently accessed. A proxy server saves time and money when browsing the Inter­net. In an office or home, you might like to restrict the web­sites that are available to different users. Some cheap shareware packages even allow you to restrict the type of access – eg, allow­ing email access only, with full access from 4-5pm daily. Intranet web server Why on Earth would you want your own web server and web pages, on November 1998  11 to try it before deciding to buy. This program features proxy caching of web pages, a firewall option and the ability to create user profiles. This last feature can be used to prevent users on one PC from accessing certain Internet protocols at various times, while giving complete access from another PC. CProxy is available for download from www.computalynx.co.uk or from www.winfiles.com/apps/98/ servers-proxy.html You will also find dozens of other routers and proxy servers at the latter site. Fig.10: proxy server software can be used to restrict access to certain Internet protocols at various times of the day and to prevent access to certain sites. A good shareware program is Computalynx CProxy V3.1 which comes with a timer, allowing you to try it before deciding to buy. your own LAN as part of an intranet? Well, an intranet can have many advantages, particularly in large organisations that need to disseminate data. An Intranet is basically a cutdown version of the Internet and you can duplicate many of its functions. If you wish to develop web pages at home, for practice, fun or profit, you can easily set up a server using Microsoft’s Personal Web Server software. This is supplied with the Front-Page 98 package and can run under Windows 95/98, handling up to 30 simultaneous requests. Users of Windows 95 can use the Windows NT Option Pack 4 (yes the NT option pack), provided it’s the Windows 95 version. There are three versions – one for NT 4 Server, one for NT4 Workstation and one for Windows 95. This option pack is available from http://backoffice. microsoft. com/downtrial/default.asp by following the links. Windows 98 users will find this software on the Windows 98 CD-ROM in the \ADD-ONS\PWS directory. This latest Personal Web Server also supports .asp web pages (Active server Pages), there­by providing an ideal place to test out web site designs without going to the expense of a fullblown Windows NT 4 Server and Web Server system. A number of other shareware or freeware web servers are also available. Check out the following two 12  Silicon Chip Mail gateways web sites for just a few of the many programs that can be downloaded: (1) http://www.winfiles.com (2) http://www.download.com If you are looking for a fully-featured web server, take a look at O’Reilly’s Web Site Pro – see http:// www.ora.com. This excellent web server also features support for Active Server Pages (.asp). A mature open standard, .asp web pages allow serv­ er-side scripting which can be very useful. As an example, it can allow your site to extract data, on the fly, from an ODBC data source and make up the new web page as it goes. With your own web server you can easily put confi­dential company information online internally for sales or other sup­port staff. With .asp web pages, it’s possible to read and write to database files and even create an accounts system, all through web pages displayed on standard web browsers. Proxy servers and safe browsing for kids If you want to stop the kids from browsing sites they shouldn’t or simply restrict their access times, a shareware proxy/firewall package is the answer. This sort of software is not only useful in the home but can also be used in a small business. One such shareware program is Computalynx CProxy V3.1 which comes with a timer, allowing you Another useful function to add into your server might be a mail server or mail gateway. Again there are a number of share­ware options available. You will need to consider how you will handle multiple user names or if you wish to stay with the one username (usually your account name). For example, let’s say that John Smith and Jane Smith would like to have their email delivered under their own names. To do this, you could arrange to have two separate dial-up accounts, with each person independently logging onto the ISP (eg, as johns<at>xyz.com.au and janes<at> xyz. com.au). However, this requires two separate calls and will attract two account fees as well. A better scheme, if your ISP allows it, is to have one log-on account (eg, smith<at>xyz.com.au) but then have separate mail accounts (johns<at>xyz. com.au and janes<at>xyz.com.au as before). Depending on the ISP, this shouldn’t cost much more that the normal charge. By using an email program that lets you set up multiple accounts, you can easily check both accounts with just one phone call. Another approach is to set up a permanent Internet feed for your server. Your server could then receive email direct instead of it going via your ISP. To do this you would have to register a suitable domain name (eg, smith.com.au) and arrange for a perma­nent connection, either phone or ISDN, to your ISP. Your ISP would then change their MX record (a mail exchange pointer) to redirect incoming mail to your mail server, instead of it going to their mail server SC for later download.