Small networks

This page was written by Christopher Spry. It is a brief outline of small computer networks which I have have installed, with an outline of what they contain and why I chose them. 

Index

1. Introduction 
2. TCP/IP network at work, with a high speed Internet connection
3. Peer-to-peer networking at home 
4. Modem dialup connections to Internet at home
5. ADSL with USB connection at home
6. Wireless (radio) networks
7. Internet Connection Sharing (ICS) for several computers on a local network
        Installing 'ICS Host' on a computer running 'Windows 2000 Professional'
        Installing 'ICS Host' on a computer running 'Windows 98 second edition' or 'Windows Millennium
        ICS Client computers
        Testing ICS and dealing with problems
8. Virtual Private Networks (VPN)
9. Other networking protocols to consider

1. Introduction

This page describes how far I have come, in networking my computers at work and at home and linking them to high speed Internet connections.

2.  TCP/IP network at work, with a high speed Internet connection

I have a PC running Windows 2000 Professional and an SGI 'Indy' running IRIX 6.5.9. They have category 5 network cables connected to a Netgear DS104 four port 10/100BASETX auto-sense compact hub.

3.  Peer-to-peer networking at home 

At home, I have a fixed PC and three portable notebook computers. Currently they are each linked in a star formation from fixed points in different rooms by category 5 network cables to a Netgear DS104 four port 10/100BASETX auto-sense compact hub. The PC and the notebook computers have 'Windows 2000 Professional'. They are connected to each other by the 'peer-to-peer' NetBEUI protocol. This works well and file transfers between them are at speeds of up to 3-MB/sec.

4. Modem dialup connections to Internet at home

Each of the computers at home has an internal modem and they can access a phone point adjacent to them. Only one computer can use the phone line at a time. I only use the modems in the notebook computers when away from home.

5. ADSL with USB connection at home

The PC at home was connected to a BT Openworld ADSL line on 1 November 2000, see 'ADSL in the UK'. 

6. Wireless (radio) networks

I am considering linking my PCs at home through a wireless (radio) network, so that the notebook computers can be used anywhere in the house. There are several ways to do this. A comparison chart of the options is available at 'Practically networked'. There is an article at 'PCWorld.com' comparing current two competing types of network, called HomeRF and 802.11b (also known as Wi-Fi). At home, HomeRF is more popular as it is cheaper and has been available to domestic users for longer. HomeRF network cards cost between $100 and $135, whereas Wi-Fi cards for home use are $100 to $175. However, 802.11b is faster and will probably overtake it, in the short-term, as the preferred installation in homes and small offices. 802.11b is also being made available as a standard feature in many makes of more-expensive notebook computer. Security is still a problem, as none of the networks yet incorporates the standard's Wireless Equivalent Privacy (WEP) encryption algorithm. All radio devices should be tested in the locations where they are to be used, before they are set up permanently, to overcome possible signal strength and interference issues. Current (April 2001) developments with radio networking is discussed at eWeek.

Note that the Bluetooth networking technology was designed for synchronizing web appliances, cell phones and other Internet browsing devices which are adjacent to each other. It was not designed for networking computers. It only supports one Mbps data rates in the 2.4 GHz band and its range is less than 30 feet. 802.11b and Bluetooth operate on the same 2.4GHz band, so there is potential for interference. It all depends on the number of devices and their proximity. 

The new IEEE 802.11a standard will allow for greater throughput in the less-crowded 5GHz band. 802.11a-based equipment is due in volume early 2002. ETSI's HiperLAN2 is the European equivalent of 802.11a and it is also due early next year.

(a) 'HomeRF' wireless ethernet

HomeRF currently runs at only 1.6 Mbps, though the next generation  of devices will support speeds of up to 10 Mbps. Although it is slower than 802.11b, it supports streaming video better, it is less susceptible to interference in its current form and it provides voice connections as well as data. It has a smaller range of up to 300 feet compared to 500 feet for 802.11b.

Products that use this protocol include:

(b) 802.11b (Wi-Fi) wireless ethernet

There is background information on the 802.11b protocol, which provides speeds of 11 Mbps transmitted at 2.4GHz. Note that other devices, such as some newer phones and microwave cookers, that use or transmit at the 2.4-MHz frequency, can interfere with traffic on these network and compatibility may be an issue.

Products that use this protocol include:

7. Microsoft's 'Internet Connection Sharing' (ICS) software

A Windows computer that has a modem dialup, ADSL or cable modem connections to Internet, can use Windows software called 'Internet Connection Sharing' (ICS) to share its connection to internet with other Windows computers on a local network. ICS software is provided with Microsoft 'Windows 98 second edition', Windows 'Millennium' and Windows '2000 Professional'. ICS enables the computer running it to become an 'ICS Host' computer, so that other computers running Windows on a local NetBEUI or TCP/IP network can become 'ICS Clients' and use the ICS Host's modem dialup, cable modem or ADSL connections to Internet. Note that use of ICS with BT's USB ADSL routers may be contrary to their 'Terms and Conditions' and is not supported by BT, so check before installing it. Computers that run Windows 95, Windows 98 (first edition) or Windows NT can connect through a local network to computers that run ICS, but cannot themselves be 'ICS Hosts'.

Installation: First, install the modem, ADSL or cable modem on the computer that will become the 'ICS Host' computer. Then install NetBEUI and/or TCP/IP on all the networked computers that are going to use the Internet connection through the ICS Host computer. Ensure that these connections are working properly, before installing or configuring ICS. It is recommended that you record your network settings, before you install or configure ICS. Note that you will be asked which connection (adapter) on the 'ICS Host' you wish to share. Only one connection can be shared. For example, if you have a modem and an ADSL connection, chose the one that will be shared on the network, before starting the installation or configuration of ICS. Installation of ICS depends on the operating system.

Installing 'ICS Host' on a computer running 'Windows 2000 Professional' There is background and detailed information on using ICS in Windows 2000 Professional, in the 'Start | Help' files. ICS is installed by default on computers that have Windows 2000 Professional. It is a Service, with a 'Manual' startup. It starts automatically when an ICS Client computer requests the service. The DHCP service, which is also used by ICS,  is also installed by default and starts automatically on the ICS Host. When you want to setup ICS, first decide which Dial-up connection is to be shared with other networked Windows computers. Then Open 'Start | Settings | Control Panel | Network and Dial-up Connections' and select the Dial-up connection that you want to be shared. Select 'Properties | Sharing' and check the 'Enable Internet Connection Sharing in this connection' box. Accept 'Enable on-demand dialling', 'Settings | Services'. On rare occasions, with special needs, you may have to select the 'Services' that ICS Clients will use and configure them for each service. Repeat the same process for 'Applications' if they are to run over the ICS network.

Installing 'ICS Host' on a computer running 'Windows 98 second edition' or 'Windows Millennium' There is a step-by-step guide at InfiniSource to installing ICS, using the 'ICS Wizard', with helpful information on how to deal with possible problems during and after installation of ICS on the 'ICS Host' computer. Use 'Start | Settings | Add/Remove Programs | Windows Setup | Add/Remove Windows components'. When the ICS software is installing, it writes several files to a floppy disk called the 'Client Configuration Disk'. When you install ICS, an 'ICS adapter' and an ICS protocol are added to the computer's configuration files. Both of these components must be present for ICS to work correctly. Once ICS has installed, open a DOS shell and type 'winipcfg.exe', which is installed with the ICS software, to ensure that there is now an adapter called ICSHARE and that the network 'bindings' are present both to this adapter and to the adapter that you will use to connect the ICS Host and ICS client computers on the local network. This is because ICS requires TCP/IP to be bound to both the ICSHARE network adapter and the adapter connecting to the local area network (LAN). ICS for the Client computers is configured on the ICS Host computer. ICS should not be installed on ICS client computers. The program (icsclset.exe) to configure the client computers is present on the 'Client Configuration Disk' made during ICS setup, but it is easier to use '%SystemRoot%\system\icsclset.exe', which was also installed on the ICS Host computer during ICS installation. 

ICS Client computers First configure 'Internet Explorer' as follows: Open 'Tools | Internet Options | Connections' and select 'Never dial a connection'. Click on LAN settings and clear the box 'Automatically detect settings'.  Clear the check box for 'Use a proxy server'. Click 'OK | OK' and close 'Internet Explorer'. Then set up the TCP/IP settings for the network card. If the computer is running Windows 9x or Windows NT version 4.0, the TCP/IP settings are found in 'Control Panel | Network'. If the computer is running 'Windows 2000 Professional', open 'Internet Explorer | Tools | Internet Options | Connections'. 

There are two different TCP/IP configurations that you can use. either (a) tell the network card to obtain its settings from the ICS Host computer or (b) provide the TCP/IP settings yourself. If (a) works on your networked computers, stay with it. It is the easiest option to setup and all the client computers have the same settings. However, if you have any problems getting the ICS Host to provide the TCP/IP settings, then use configuration (b). I have tried (a) and after it failed on several occasions to provide the correct TCP/IP settings, so I have setup (b).

In both cases start by clicking 'Start | Settings' and click on 'Network and Dialup Connections'. Right click on the ethernet card entry which is used by your network and open 'Properties'. Click on 'Internet Protocol (TCP/IP)' then click on Properties. 

(a) Select 'Obtain an IP address automatically. Click on 'Obtain an IP address automatically' and click on 'Obtain DNS server address automatically'. These settings cause the ICS Client to obtain automatically an IP address (192.168.0.*), and to provide the default gateway IP address (192.168.0.1) and the DNS server's IP address (192.168.0.1) from the ICS Host computer, which is the local DHCP server.

(b) Select 'Use the following IP address' (to 'force' IP, Gateway and DNS settings onto the network card) and enter: 192.168.0.2, 'Subnet mask' 255.255.255.0, 'Default gateway' 192.168.0.1 and 'Preferred DNS server' 192.168.0.1. If you have several computers to setup as ICS clients, they should have different IP addresses. So the second could be '192.168.0.3' etc. Click 'OK | OK'. The system may have to restart to accept these settings. 

Testing ICS and dealing with problems

After setting up ICS on the host and client computers, open a DOS shell on one of the ICS client computers and type 'ipconfig /all'. The output should include the following four entries:

IP Address. . . . . . . . . . .... . : 192.168.0.2         (Or another similar IP address provided by the ICS Host)
Subnet Mask . . . . . . . . .. . . : 255.255.255.0    (This must be 255.255.255.0)
Default Gateway . . . . . . . . . : 192.168.0.1        (This must be 192.168.0.1)
DNS Servers . . . . . . . . .. . . : 192.168.0.1         (This must be 192.168.0.1)

Once you see that these entries are correct, you can open 'Internet Explorer' and check that you can access Internet through the ICS Host computer. If the 'IP address' line 'Default Gateway' or 'DNS Servers'' lines are  blank or incorrect, or the subnet mask is something other than 255.255.255.0, then the ICS Host computer is not providing the network card on the client computer with the addresses it needs and the ICS Client computer will not be able to access Internet. My experience is that these settings are often difficult for the ICS client network card to obtain, for reasons that I do not know. I have found this to be a particular problem with portable and laptop computers which are taken to and from an ICS network. If the network card on the ICS Client computer is not being provided with useable TCP/IP information by the ICS Host computer, follow the procedure (b) above to 'Use the following IP address'.

The IP address of the ICS Host, as seen by ICS Client computers is '192.168.0.1'. This is useful when you want to use the Web or telnet services on the ICS Host computer from a local ICS Client computer. Computers on other networks will not be able to connect to ICS client computers using their IP address, so it is not necessary for ICS Client computers to run a firewall, although you might like to do so for other reasons. For other computers on Internet, the 'ICS Host' computer will have whatever IP address was given to it by the internet service provider or network manager (not '192.168.0.1' which is a 'reserved' address).

There is more information on ICS in Microsoft's Knowledge Base Articles, with an overview, a description, support, use with Outlook Express, list of error messages when using it and a FAQ. ICS can be disabled, after it has been installed. 

ICS should always be used with a firewall. ICS is compatible with the 'Zone Alarm' firewall software. I have installed the ' Zone Alarm Pro' program. I found that I had to configure 'ZoneAlarm Pro' on the host and client computers to use 'Internet Connection Sharing' as a host and client respectively, before the client computer could use the ADSL connection. If you consider that you are being attacked, see advice at 'my | NetWatchman'.

8. Virtual Private Networks (VPN)

Virtual Private Networks (VPN) are among the best protocols to link computers securely over Internet. There is a variety of 'tunnelling network' protocols to enable VPN. Microsoft's Windows 2000 'VPN', 'Nortel VPN' and 'VNCviewer'. Microsoft's Windows 2000 'VPN', which is included in 'Windows 2000 Professional' and 'Server' editions, provides the 'point-to-point tunnelling protocol' (PPTP) and the 'layer two tunnelling protocol' (L2TP). A fixed IP address is required for VPN. VPN can be used with ADSL. Some Internet Service Providers provide a 'managed VPN' service for commercial users, for example Minitour in the UK.

9. Other networking options to consider

Please let me know about errors and omissions.

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© cspry@sghms.ac.uk. Department of Biochemistry & Immunology, St. George's Hospital Medical School, London SW17 0RE, UK. Phone +44 20-8725 5819; fax +44 20-8725 5821. This page was updated on 02 January 2002 10:40:40