Windows 2000 supports both Network Address Translation (NAT) and Internet Confection Shading (ICS) al1ow workgroup users to access to the Internet.. Windows 2000/XP Professional support only ICS. Internet Connection Sharing (ICS) enables a Windows (Win98SE, Win2K and XP) computer to share its Internet connection with computers on local area networks. The computer connecting directly to the Internet and shares its connection with the rest of the computers on the network called the ICS host. In addition, the ICS host provides DHCP to ICS clients. Client computers are protected because they cannot be seen from outside the network. Only the computer running ICS is seen from the public side.

We assume you have all computers physically connected, and the ICS host have two network connections: one (for example Internet in our case) for the Internet such as a dial-up (PPP or ISDN), cable modem, DSL, or other broadband Ethernet connection, and another one (LAN) , for the local area network.

1. When you enable Internet Connection Sharing, IP address of the Interne NIC in the ICS server is always 192.168.0.1. All clients will be assigned other IP addresses in the 192.168.0.x range.
2. You should not enable ICS on the computer as a domain controller, DHCP server, or DNS server.
3. To enable ICS, you must be logged on as a member of the Administrators
4. You may experience some problems if you use NetMeeting and VPN in your ICS network.
5. You should have two NICs.

To configure a WinXP ICS host, go to Start>Control Panel>Network Connation. Highline the Internet which connecting to a cable modem in our case. Under Network Tasks, click Change settings of this connection. On the Advanced tab, select the Allow other network users to connect through this computer's Internet connection check box.

To setup a win9x (in our case) as ICS client to access the internet, you need to do two things. network settings and internet option settings.

1. Network settings must be set Obtain IP Address Automatically - to do this, go to Network>Properties of TCP/IP.
2. The Internet browser should se set never dial a connection and no proxy server - go to Internet Options>Connection and LAN settings.

Can ping other computer and Internet but not default gateway IP

Symptoms: you are running ICS on XP and all networking computers can access the Internet. Problems: 1) you can't access the ICS host. 2) you can ping other networking computers and Internet IP but not ICS host. 3) when using tracert (public) ip, the default gateway, ICS, is time out. After passing the gateway, all IPs reply.

Resolutions: 1) disable ICF. 2) there is firewall running and you may need to disable.

For step by step setup ICS, visit this page: http://www.howtonetworking.com/RemoteAccess/remoteassitance1.htm.

"Cannot enable shared access" while setup ICS

SYMPTOMS: When you try to enable ICS on your Win2K/XP on a network, you may receive the following error message:
"Cannot enable shared access." and "Error 783: Internet Connection Sharing cannot be enabled.

RESOLUTION: When you enable ICS, your computer is assigned the 192.168.0.1 IP address, and if this address is already in use on another computer, the error message listed earlier in this article is generated. To work around this problem, disconnect the computer using the 192.168.0.1 IP address from the network, or change its IP address to something other than 192.168.0.1.

Cannot enable ICS

1. ICS cannot be used and will not be shown if you have enabled a network bridge.
2. There are at least two enabled, connected network connections.
3. Make sure ICF is disabled on the LAN connection.

Can't access the Internet by name through the NAT enabled server

Symptom: you set up NAT on your Routing and Remote Access server. The users can connect to the Internet using IP addresses but not the web site name. How can you fix it?

Resolution: on the properties dialog box of the NAT server in the Routing and Remote Access console, check the Clients Using Domain Name System under the Name Resolution tab.

Client with Static IP can't access the Internet

Many people have a difficulty to make static IP client to work with ICS. The client and host can ping each other but not Internet. Since the client is assigned static IP so that it also need to be assigned the DNS manually. To do that, go to properties of TCP/IP>Advanced>DNS to add your ISP DNS.

Error 761 - An error occurred while Internet Connection Sharing was being enabled. The dependency service or group failed to start.

Resolutions:

1. If you use ICS, make sure your have two NICs and the inside NIC should be 192.168.0.1.

2. Make sure the following services are running

Application Layer Gateway Service
Network Connections
Network Location Awareness (NLA)
Plug And Play
Remote Access Auto Connection Manager
Remote Access Connection Manager
Remote Procedure Call (RPC)
Telephony

ICS dial-up runs automatically after another computer logon

Symptoms: after you setup ICS on an XP dial-up connects to the internet, the dial-up connects to the ISP automatically whenever a user logs on to another XP box on the network (without running IE).

Resolution: there are some applications such as MS messenger and Anti-Virus Live Update that may be trying to access the internet on boot. For this reason, by default the ICS connection will connect to the internet when there is any traffic from the network. To disable this feature, open the Network Connections folder and right-click on the connection that is shared. Click the advanced tab and uncheck the "Establish a dial-up connection whenever a computer on my network attempts to access the internet". If you make this change then you will have to connect to the internet manually from the ICS box so that others can use it.

ICS Does Not Allow Other Users to Connect After You Log Off

Symptom: you setup ICS for other LAN clients to access the Internet. As long as you logon, it works. After the you logs off, the LAN clients can't establish a connection any more

Resolution: This behavior can occur if the user saves the password before establishing the shared connection. That password and the ICS password are saved in different registry locations. When a LAN client tries to log on, the system looks in the ICS password key, finds no password, and denies access. To fix this problem, delete and then recreate the connection, without setting the username or password from the LAN clients. After you establish the connection, click to select the Save Password check box when you log on.

ICS or NAT

1. When you have a server running DHCP or Dynamic DNS, ICS service may not function correctly or may cause some services to stop working. In addition, various error messages may be caused.
2. Windows 2000/2003 Server provides more robust internet sharing utility called Network Address Translation. The NAT has additional features that may make it a better than ICS in a server or domain environment.

ICS Host can assign IP

The ICS Host can automatically assign IP addresses to internal network clients. You may want to use this functionality if you do not have a DHCP server.

ICS with a yellow exclamation point

SYMPTOMS: When you view the ICS Adapter in Device Manager, you may see a yellow exclamation point. This issue can occur if you do not run the ICS Setup wizard after you install Windows.

RESOLUTION: 1) To resolve this issue, run the ICS Setup wizard. To do this, go to the Connections properties, click Sharing. 2) If the ICS Adapter is not in Device Manager, you must reinstall ICS. To do this, go to Add/Remove Programs>Windows, uncheck Internet Tools first. After rebooting, recheck Internet Tools.

ICS doesn't show under Advanced

To enable ICS, you must have two NICs. Otherwise, you won't be able to enable ICS and you even can't see this option. If you do have two NICs instilled on your computer, make sure none of them is disabled.

ICS Issues

It is not recommended to setup ICS to uses static IP; to be on a domain controller, VPN, DNS servers, gateways, or DHCP servers.

Symptoms if ICF is enabled on the LAN connection

1. You may receive "System error 6118 has occurred. The list of servers for this workgroup is not currently available" or "System error 53. The network path was not found" message if using net view command on local computer and net view \\icfcomputer or net use \\icfcomputer from remote computer.
2. You may receive "Workgroup/ICF Computer is not accessible. You might not have permission to use this network resources. Contact the Administrator of this server to find out if you have access permission. The network path was not found." message when click the Workgroup or the ICF computer (ICS computer is listed here because the cache) from ICF computer or remote computer.
3. Can't ping the ICF computer by IP or name.
4. Browstat.exe shows no master browser.
5. Can't ICS computer web site.

ZoneAlarm Firewall Issue

If you are using ZoneAlarm Firewall, that may be the problem for the ICS.

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How to Setup Internet Connection Sharing (ICS)

ICS Does Not Allow Other Users to Connect After You Log Off

Symptom: you setup ICS for other LAN clients to access the Internet. As long as you logon, it works. After the you logs off, the LAN clients can't establish a connection any more

ICS or NAT

ICS with a yellow exclamation point

SYMPTOMS: When you view the ICS Adapter in Device Manager, you may see a yellow exclamation point. This issue can occur if you do not run the ICS Setup wizard after you install Windows.