Quick Beginnings

Configuring TCP/IP on OS/2

To run the Control Center on OS/2 Warp 4 while disconnected from a LAN, you will need to configure TCP/IP to enable local loopback and localhost. If you are running OS/2 Warp Server for e-business, local loopback is enabled by default.

Enabling Local Loopback

To enable local loopback on your system:

1. Open the System Setup folder.
2. Open the TCP/IP Configuration notebook.
3. View the Network page.
4. In the Interface to Configure list box, highlight loopback interface.
5. If the Enable interface check box is not selected, select it now.
6. Verify that the IP address is 127.0.0.1 and Subnet Mask is empty.

Enabling Localhost

To enable localhost on your system:

1. To check if localhost is enabled, enter the ping localhost command.
   • If data is returned and localhost is enabled, you can skip steps 2 and 3 below and go directly to step 4.
   • If localhost unknown is returned, or if the command hangs, localhost is not enabled. Go to step 2.
2. If you are on a network, make sure that loopback is enabled. To enable local loopback see Enabling Local Loopback.
3. If you are not on a network, enable localhost by performing these steps:
   1. Add the following line after other ifconfig lines in the MPTN\BIN\SETUP.CMD command file:

         ifconfig lo 127.0.0.1
      

   2. In the TCP/IP configuration folder, perform the following steps:
      1. Go to the Configure Name Resolution Services page.
      2. In the Hostname configuration without a Nameserver table, add an entry with IP Address set to 127.0.0.1 and Hostname set to localhost.

      Note:

      If you have a hostname for your machine on the Configure LAN Name Resolution Services page, you must add this name as an alias when you set the IP Address 127.0.0.1 to localhost.

   3. Select the Look through HOSTS list before going to the nameserver list box. This step tells your OS/2 system that when it is looking for a host, such as localhost, it should use the host address found on your machine rather than checking the nameserver. If the host is not defined on your machine, OS/2 continues looking for the host by using the nameserver you configured.
   4. Close TCP/IP Configuration and reboot the system.
   5. You should be able to ping localhost without being connected to any network.
4. Verify that your hostname is correct. On an OS/2 command line, enter the hostname command. The hostname returned should match the one listed in the TCP/IP Configuration notebook on the Hostnames page and it must be less than 32 characters. If the hostname deviates from these conditions, correct it on the Hostnames page.
5. Verify that your hostname is set properly in CONFIG.SYS. You should see a line similar to the following:

   SET HOSTNAME=<correct_name>
   

   where <correct_name> represents the value returned by the hostname command. If this is not the case, make the necessary changes and reboot your system when you are finished.

Verifying TCP/IP Configuration on OS/2

If you are having trouble running the Control Center on OS/2 while disconnected from a LAN, try running the sniffle /P command to diagnose the problem.