This page is not a tutorial on either TCP/IP or Proxies.
IP Address Subnet Mask
169.1.2.0 Local subnet address
169.1.255.255 Subnet broadcast address
127.0.0.1 255.0.0.0 Dedicated loop back address.
Also known as localhost or
default.
0.0.0.0 Default route
224.0.0.0 Multicast address
255.255.255.255 255.255.255.255 Limited broadcast address
TCP/IP basics is well written and illustrated. Read this first for some good background.
| ipconfig | NT only. Display the IP address, gateway address, etc. for this computer. | |
| winipcfg | 95 & 98. Display the IP address, gateway address, etc.
for this computer.
Use one of the following
to copy this information to the clipboard
| |
| ping | Check if this computer can see (send messages to) the target computer. Should work with both an IP address and a server name. | |
| arp | Address Resolution Protocol Cache - Maps an IP address to a network card address. Use arp -a to view the current contents. When reconfiguring a network, you may need to manually clear this cache. | |
| tracert | Trace Route - Determine the route that a message takes when it goes from one computer to another. | |
| nslookup | Use this to lookup the IP address assigned to a server name, or to find the name assigned to an IP address (reverse DNS). (Not available in Windows 98.) web version |
Both ping and tracert rely on the server being able to respond to a ping. Unfortunately, many servers have disabled this feature for security reasons. In addition, some firewalls block ping's. However, both of these commands can still be used to trouble shoot local problems.
Try Helmig's Trouble Shooting Center. This archive is great and has helped me solve many problems not documented elsewhere.
How to Troubleshoot Basic TCP/IP Problems in Windows NT 4.0
TCP/IP Routing Basics for Windows NT - This describes the data returned by route print, including what the subnet mask is.
Default Gateway Configuration for Multihomed Computers, ie, computers that have multiple network interfaces.
How To Configure Windows NT as a Remote IP Router - Though this applies to NT only, it does explain the concept of configuring a router.
In order to connect multiple computers to the internet using a single modem, you need to configure your LAN to communicate using TCP/IP (one of several possible protocols). Each network card will need its own IP address and the modem will need its own address. This means that the machine with the modem will actually need 2 addresses: one for the network card and a different one for the modem.
If you are running a DHCP server (such as Windows NT 4.0 Server), then you should use DHCP to provide IP addresses (except that the proxy server must have a fixed address). For the rest of us, you must manually assign an IP address to each machine on the network. By convention, addresses of the form 192.168.x.y are reserved for private networks (but you can use any address you want). For each machine, you must use a unique IP address. If your subnet mask is 255.255.255.0, then the first 3 numbers in the IP address should be the same for each machine and the fourth number should be unique - such as 1, 2, 3 etc.
Using Control Panel / Network, select the TCP/IP protocol connected to your network card and modify its properties. Set the IP address to something like 192.168.1.1 and the subnet mask to 255.255.255.0. (Remember, each machine needs its own IP address.)
On the one machine with the modem, under Control Panel / Network, the TCP/IP protocol connected to Dial Up Networking should be set to use DHCP (ie to obtain an IP address automatically). This address will be set by your ISP (Internet Service Provider). If you set it, you will not be able to connect to the internet.
The one thing that you must know is the DNS address. Hopefully, most of you will have an easier time getting this than I had. This describes how I found the cpcug PPP Parameters.
VSocks come with its own very good help files.
However, some Microsoft programs don't (well, I was suprised :) Netscape Communicator xxx seems to work fine. Ping connects and uses DNS to convert a server name to an IP address. (The rest of the Ping function will not work due to proxy limitations.)
Basically, this is where to look if you can ping a machine using an IP address, but using a computer name fails.
| hosts | Used for host name to IP address look up |
| hosts.sam | A sample file which explains the file format |
| lmhosts | Used for NetBIOS name resolution when WINS is not used |
| lmhosts.sam | A sample file which explains the file format |
ping provides regular and reverse DNS lookup from a command prompt
nslookup
provides regular and reverse DNS lookup from a command prompt
(enter either a server name or an IP address)
(not available in Windows 98)
web version
The Dial-Up Networking profiles are stored in the registry under
HKCU/RemoteAccessA lot of times when accessing your local machine using PWS (Personal Web Server), ping etc., the system tries to dial your ISP instead of handling the access locally. Adding a proxy server helps. However, without the proxy, it isn't really clear how all this works. Be sure the name resolution is in the host file. In IE 4.0 ver 4.72, under View / Internet Options... / Connection, set connect ... using a LAN instead of ... using a modem. This is stored in the registry under
HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings\
EnableAutodial = 00 00 00 00 LAN
EnableAutodial = 01 00 00 00 Modem
You will still be able to dial to the internet,
but you must manually connect using
Start / Programs / Accessories / Dial-Up Networking.
(This used to work automatically without this fix,
but something got broke
and now Windows always dials up before it finds
default, 127.0.0.1, and others.)