OS/2 Technical Support - TCP/IP Networking

Things common to these help files:

The disk drive specification d: is used in all the examples. Replace d: with the drive letter of your OS/2 boot disk.

DDNS = Dynamic Domain Name System
DNS = Domain Name Server
FTP = File Transfer Protocol
HTTP = Hyper Text Transfer Protocol
HTML = Hyper Text Markup Language
IP = Internet Protocol
IP address = 4 numbers separated by periods like 192.168.1.200
ISP = Internet Service Provider
POP = Post Office Protocol
PPP = Point to Point Protocol
SLIP = Serial Line Internet Protocol
SMTP = Simple Mail Transfer Protocol
TCP = Transmission Control Protocol
TCP/IP = Transmission Control Protocol/Internet Protocol
UDP = User Datagram Protocol

Setting up a TCP/IP network

The first thing that is required is that the TCP/IP protocol be running on your network adapter. If you are not sure, you can run MPTS, also known as "Adapters and Protocol Services" in your System Setup folder. Your network adapter should have the "IBM TCP/IP" protocol attached to it. You may also have "IBM OS/2 NETBIOS" if you are also running PEER on that adapter. See The difference between PEER and TCP/IP.

Let's say that you have 3 machines with the following IP addresses:

  • A 192.168.1.1
  • B 192.168.1.2
  • C 192.168.1.254

The assignment of these IP addresses is fairly arbitrary except that 192.168.x.x is reserved for private networks, and 0 and 255 are "special" so don't use them for machine addresses. I have chosen machine C to be the machine with the Internet connection to the outside world. This machine will act as the Internet gateway for the rest of the network. If you have more machines, simply increment the last number in the IP address for each machine so that each machine has a unique IP address:

  • D 192.168.1.3
  • E 192.168.1.4
  • ...

On each machine open "TCP/IP Configuration" in the "System Setup" folder.

On the network tab, highlight "LAN interface 0", check "Enable interface", "Manually, using:" and type the machine's IP address into the "IP address" field. The Subnet Mask for this address range is 255.255.255.0. Highlight "loopback interface" and check "Enable interface", "Manually, using:", 127.0.0.1.

Machine A would look like this:

TCPCFG1

Then go to the "Routing" tab. You should see "NO ENTRIES". If not, delete all the entries there. Click "Add". "Route type" = Default, "Router address" = 192.168.1.254, "Metric count" = 1.

TCPCFG2

Then click "Add". Uncheck "IP Forwarding" on all machines except machine C.

TCPCFG3

Then go to the "Hostnames" tab. Fill in "This machine's hostname" and "Local domain name". Also, highlight "NO ENTRIES" under "Nameserver addresses" and click "Add" to add both of the nameservers (DNS) provided by your ISP.

TCPCFG4

Go to page 2 of the "Hostnames" tab. Add all the local systems to the list and check the "Look through HOSTS list before going to nameserver" box.

TCPCFG5

Once you have made these changes to all the machines and rebooted them all, you should be able to ping any machine from any other machine.

Also, if you are using the InJoy dialer on machine C and enable NAT, all the machines on your network will be able to reach the Internet through machine C.

If you have a cable modem or DSL on a second adapter in machine C, you need to enable the second adapter and install some kind of gateway software such as the InJoy Firewall. Go to the "Network" tab in "TCP/IP Configuration" and highlight "LAN interface 1". Check "Enable interface". If your ISP uses DHCP, check "Automatically, using DHCP". Otherwise check "Manually, using:" and type the IP address given to you by your ISP into the "IP address" field. Also use the Subnet Mask given to you by your ISP.

AT&T Worldnet and OS/2

There is really nothing special about AT&T Worldnet. You can use them as an ISP with any dialer and PPP stack. Personally, I use InJoy, so that is what I will describe first. InJoy is a completely self contained dialer and PPP interface in one, so you don't have to download or update different pieces to get your Internet connection working. (Acronyms are defined at the top of this page.)

Setting up a system to access an ISP and the Internet is really quite easy. Unfortunately, getting all the information is quite difficult for most ISPs, and this assumes that you know what information to look for. The other thing that makes this task difficult is knowing what to setup in which applications to make everything work. This section will attempt to explain how to setup a system to use the Internet in a plain and easy to understand way. I will use the InJoy dialer and AT&T Worldnet in the examples, but the procedure is the same regardless of which dialer or ISP you use.

This is the information you need:

  • The phone number to dial for modem access.
  • Your dialup login name and password.
  • 2 Domain Name Server (DNS) IP addresses. (Only 1 is required, but you usually get 2. 1 primary and 1 backup.)
  • The POP server name or IP address. (For receiving e-mail.)
  • Your e-mail login name and password.
  • The SMTP server name or IP address. (For sending e-mail.)
  • The news server name or IP address. (For reading Usenet newsgroups.)

Now let's talk about each item.

The phone number

For AT&T Worldnet, you can find a phone number here.

The user names and passwords

These are supplied by your ISP when your account is created. They are unique to each individual account. For IGN, if your e-mail address was sally@ibm.net, your dialup login name was internet.usinet.sally, and your password was supplied and you could change it. The e-mail login name was just the first part of your e-mail address, sally, and the e-mail password was the same as the dialup password.

On AT&T Worldnet, the dialup user name and password are different than the e-mail user name and password. In other words, the dialer would use one login name and password to establish the connection with the ISP, and the e-mail client would use a different login name (the e-mail name) and password to log into the POP server. The dialup login name was something like 123456789@worldnet.att.net, and the password was a long sequence of random characters. Neither was changable by the user. The e-mail user name was the name part of your e-mail address (sally in the above example), and the password was something you selected.

The Domain Name Server IP addresses

These are supplied by your ISP. Small, local ISPs typically use the same DNS addresses for everyone. Large ISPs like IGN and AT&T Worldnet have several DNS and they try to split the load between them by assigning you different DNS IP addresses depending where you are located. To see what DNS you are currently using, look in d:\MPTN\ETC\RESOLV while you are connected.

The POP server name or IP address

These are supplied by your ISP. Small, local ISPs typically use the same POP server for everyone. Large ISPs like IGN and AT&T Worldnet have several POP servers and they try to split the load between them by assigning you to a specific POP server depending on your location. You must use the correct POP server because that is the only one that has your e-mail on it. Usually the POP server name is supplied. You could also use the POP server IP address and eliminate the DNS lookup of the name, but this is not recommended because your ISP can change the IP address of the POP server. Using the name eliminates this potential problem.

The SMTP server name or IP address

These are supplied by your ISP. Small, local ISPs typically use the same SMTP server for everyone. Large ISPs like IGN and AT&T Worldnet have several SMTP servers and they try to split the load between them by assigning you to a specific SMTP server depending on your location. It doesn't really matter what SMTP server you use because this is simply a portal that your e-mail goes through to get to it's destination. The SMTP server doesn't even have to be one provided by your ISP. This is how may spammers attempt to stay anonymous. To avoid this many ISPs don't allow access to the SMTP servers unless the access comes from within the same domain. In other words, you can only use an ibm.net SMTP server if you dialed in using an ibm.net account. You would be denied access to an ibm.net SMTP server if you dialed in using an earthlink account. Knowing this becomes important when we setup the e-mail client. Usually the SMTP server name is supplied. You could also use the SMTP server IP address and eliminate the DNS lookup of the name, but this is not recommended because your ISP can change the IP address of the SMTP server. Using the name eliminates this potential problem.

The news server name or IP address

These are supplied by your ISP. Small, local ISPs typically use the same news server for everyone. Large ISPs like IGN and AT&T Worldnet have several news servers and they try to split the load between them by assigning you to a specific news server depending on your location. Usually the news server name is supplied. You could also use the news server IP address and eliminate the DNS lookup of the name, but this is not recommended because your ISP can change the IP address of the news server. Using the name eliminates this potential problem.

Once you have the required information, the first step is to get the dialer to connect and establish your Internet connection.

This section not done yet...

Making Windows access TCP/IP services on an OS/2 network

These instructions are for making a Windows 95/98 system access TCP/IP services that are served by another machine on your existing LAN. It is assumed that the access is through a single adapter, and no dialup access is required. It is also assumed that PEER services are also running on the LAN and that the Windows machine also makes use of the PEER services. (Windows NT is much more difficult to setup, although the philosophy of what needs to be done is the same.)

  1. Open My Computer, then Control Panel, then Network.
  2. Click on the Configuration tab. For PEER and TCP/IP, you should have the following items there. If not, click Add and add them. Use the items in "Microsoft" when adding items. If you have other items, you can (and should) remove them.
    • Client for Microsoft Networks
    • Some kind of network adapter
    • NetBEUI -> Network Adapter
    • TCP/IP -> Network Adapter
    • File and printer sharing for Microsoft Networks
  3. Highlight the TCP/IP item and click the Properties button.
    • Click on the IP Address tab. If you are using DHCP to assign IP addresses click the box next to "Obtain an IP address automatically", otherwise click the box next to "Specify an IP address" and fill in the "IP Address" and "Subnet Mask" for this system.
    • Click on the DNS Configuration tab.
      1. Fill in the Host field with the name of the computer.
      2. Fill in the Domain field with the name of your local domain.
      3. Click the button to Enable DNS.
      4. Fill in the IP address of the two Name Servers (DNS) provided by your ISP. Don't forget to click the "Add" button to add them to the list.
    • Click on the Gateway tab. Fill in the IP address of the local gateway PC in the "New Gateway" field and click the "Add" button. If you are using the InJoy gateway/firewall, this is the local IP address of the InJoy machine.
    • Click on the Bindings tab. Uncheck all the entries in the list. When you switch to another tab, or click OK, you will be presented with a dialog box that says, "You have not selected any drivers to bind with. Would you like to select one now?". Answer No. If this box pops up again, answer No again.
    • Click on the NetBIOS tab. Make sure that the check box next to "I want to enable NetBIOS over TCP/IP" is either not checked or greyed out.
    • When you have finished making all the changes, click on the OK button.
  4. Click on OK and the system will install some files and reboot.