One thing Windows networking has not made easy is sharing a modem. This generally translates into the machine with an Internet connection (in other words your computer!) being in highest demand. You can turn to Proxy Servers or Network Address Translation (NAT) to get your computer back.

Both Proxy Servers and NAT start with the same basic idea. They are software components that run on a machine with an Internet connection, which may be a dial-up modem, ISDN line, cable modem, or ADSL modem. Client computers on your network pass requests for Internet services to the Proxy Server or NAT gateway; in turn, these requests are sent to the Internet. Packets coming in from the Internet are accepted by the Proxy Server or NAT gateway and passed on to the appropriate client computer. Only the computer acting as proxy or NAT gateway needs a valid Internet-routable IP address. Other computers on your LAN are assigned IP addresses set aside for private networks. 

Proxy Server headaches

Proxy Servers are somewhat complex beasts. I used to use WinGate 2.1d from Deerfield Communications. The server portion was fairly straightforward to configure. Clients were a bit more difficult. You must configure your software to work through a Proxy Server. In some cases, this is simple: for example, Internet Explorer has a menu option that directs it to use a Proxy Server. Other programs were neither easy nor possible to use through a Proxy Server. I could never configure Microsoft Outlook to work through WinGate 2.1 to access an Exchange Server. Another problem I had was being able to access multiple news servers. The first one was relatively easy to configure. Subsequent news servers, while possible, were a pain to configure. I never did manage to get Telnet to work through WinGate. 

I read on an Internet mail list that NAT was easier and more capable: I went looking. WinGate 3.0 had just been released, but I had a recommendation of SyGate 2.0 from SyberGen Inc. and I decided to try it. By the time you read this, version 3.0 should be available. 

SyGate

You install the software on the machine with the Internet connection; it must be running Windows 95, 98, or NT4.0. SyberGen lists the minimum system requirements as a 486 with 16MB RAM and 10MB disk space. If you hope to use the machine for anything more than just SyGate, I think a more realistic minimum is 32MB RAM-my recommended minimum for running any 32-bit version of Windows. Other computers on your LAN can be running just about any operating system as long as they have a TCP/IP stack. 

I was surprised at how easy it was to set up SyGate. You must specify the connection type since permanent connections such as ADSL or cable modem are handled differently than dial-up connections. If you are using ADSL or cable modem, you need two network cards in the SyGate gateway machine. One connects to the ADSL or cable modem and the other to your internal LAN. If you use a dial-up connection to the Internet, you specify the DUN connectoid to use. Optionally, you can set a time-out value and the SyGate machine will hang up the connection after a period of inactivity. 

After that, you configure TCP/IP on each machine on your LAN. The SyGate manual gives very clear instructions. Since SyGate has a DHCP server included, you don't even have to assign most TCP/IP settings-just by telling each client computer to use DHCP and the IP address, the SyGate machine sets the Network Mask, Gateway, and DNS. If you prefer, you can disable the DHCP server and set all TCP/IP settings manually. Again, the SyGate manual provides very clear instructions. 

At this point, you should be able to run virtually any Internet application from any machine on the LAN. If a connection to the Internet is not open, the SyGate machine will establish one automatically. If you are concerned about the possibility of automatic connections being opened and left open, you can turn this feature off. 

The most difficult area for me was to reconfigure my Internet apps to cease using a proxy server. That is the beauty of a NAT gateway. You simply configure most applications as if you have a permanent connection to the Internet and they work! I tested e-mail programs (accessing both POP3 and Exchange Servers), FTP clients, Telnet clients, PING, News readers, Network Time Protocol clients, a WinFrame client, and more. 

I originally had some problems accessing my Exchange Server. Once I added the NetBIOS name of my Exchange Server to my HOSTS file (which was not required when accessing my Exchange Server from the machine running SyGate) I was able to connect to my Exchange Server. Keep this in mind when using a program like SyGate. Even though most programs should work fine, you may run into some programs that act differently under SyGate. Another example is ICQ: it will require a few special settings that are detailed in the SyGate manual. 

SyGate includes a monitor that you can use to see the traffic flowing to and from client computers and the Internet. You can also enable and disable SyGate, but I found that disabling SyGate disabled the Internet connection on the SyGate machine. Only a re-boot could re-enable it. 

It is really nice to be able to use all my Internet applications from any computer on the network. The nature of many Internet connections tends to be "bursty"-short spurts of lots of traffic followed by extended periods of little or no traffic. This lends itself well to sharing a connection. Even a 28.8Kb dial-up connection may be shared by several users. In many cases, users will not notice that they are sharing the connection. 

You can download SyGate from www.sygate.com. The version you download will allow you to transfer 75MB of data, which should be enough to verify if it works for you. The 23-page User Guide is available in HTML and Adobe Acrobat formats. 

You can register your copy of SyGate to unlock it for unlimited traffic. All licenses are for simultaneous connections and a user on the SyGate machine is never counted. Prices in US dollars are: 3 users - $49; 6 users - $99; and unlimited - $199. 

Membership has its rewards

OPCUG members can get a 15% discount by registering at www.sygate.com/oem.htm and entering "ZX0398" (that's ZX'zero'398) as the OEM code. 

If you want to read more on NAT, it is defined in RFC1631 and is available in the Internet file area on PUB II as RFC1631.ZIP. 

Maybe now, you can get back on your own computer sometimes.

Bottom Line:

Sygate (Proprietary, $49 - 3 users)
Version 2.0
SyberGen Inc.
http://www.sygate.com