OS/2 eZine

16 July 2000

Ben Dragon is a self-described "Part-time Networking Translator." When he's not explaining to the world how networking works, he's busy configuring his computers to do common household chores....

If you have a comment about the content of this article, please feel free to vent in the OS/2 eZine discussion forums.

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OS/2 and Home Networking, Part 3

Hey you there! Relax your grip on that mouse! As the Chair and co-founder of the MEEK!, (Mouse Extrication Everywhere Klan!) it is my duty to inform you of a scheduled uprising against mouse-crushers everywhere! It is planned for and will be executed on this very day! Be warned! When the mouse-ball-to-end-all-mouse-balls starts rolling its wrath will be terrible, its judgment swift and its vengeance bloody! So next time you whack your mouse out of frustration generated from a slow dial-up connection, just remember... your time is coming! Now, back to your regularly scheduled networking article... Part III to be precise.

Greetings networking neophytes! Last week we covered the basic installation and initial configuration of the networking software for OS/2. Picking up from there we will have assumed a reboot ensued and you are now stuck at. "SIOCADDRT: network is unreachable.


I will be dealing with both TCP/IP 4.0 that comes with OS/2 Warp 4 and the once, briefly free, after-market TCP/IP 4.1. Where possible I will include references to both but if something sounds unfamiliar or does not correspond to your setup, chances are I'm referring to the version that you don't have. So feel free to either skip over a few lines or send me a fist full of twenty dollar bills with a hearty congratulations on the incredible job I'm doing! 8)

Also take note that the graphics included here are from the TCP/IP 4.1 version.

There are many problems that can cause a few boot errors when working with networking and TCP/IP. You would be surprised how many of them come down to entering the wrong number or an incorrectly entered number. Subnet mask, feedback loop, IP addresses all contain numeric entries. One number out, one misplaced zero, (or decimal), can leave your networking setup open to possession by any number of strange demons. The worst of the worst of the corrupters, (and whose name is only whispered in soft tones on a quiet night in a darkened room), is named Be-El Gaih'Ts.

**Mandatory Gates Grinding**

His twisting and shagging of long established practices and standards has been convenient for his takeover though nothing but a pain for non-MS OS network-ers. Can't get long file names under Windows viewed through the network on non MS OS'? Well you know the demon to denigrate! True, IBM could conform and update things to the latest MS-driven networking standard revisions, but IBM is not the cause!

**Normal subject restored**

One of the most common and least documented errors is the foul and terrible; "Route: command failed: network is unreachable." (4.1). Many a stout heart has failed and more, terrified faces, have blanched at this one than all others; "SIOCADDRT: Network is unreachable." (4.0). This problem is caused by a mis-configured or incorrectly set router address in the TCP/IP configuration. Note that these error messages are given only during boot time and will stop your computer awaiting a carriage return, (hit the "Enter" key). Essentially, OS/2 can't find your TCP/IP router and/or can't configure your LAN 0 interface at bootup. Once again check your TCP/IP configuration! Have you checked it all ready? Is that once or twice? Then check it a third time. I cannot over express how many times users have been certain the numbers were right only to find themselves red-faced and shy-eyed when the support expert points out the error of their ways.


One important difference should be pointed out between TCP/IP versions 4.0 and 4.1; in 4.0 you are required to input both a default route, (EX:, AND a net route for the same address. If you enter the default route the software will automatically enter the net route for you. Note that you can only and need only, have one default route while you can have many NET routes. Now if you try this under TCP/IP 4.1 you'll find that your Internet connection will disappear mysteriously after twenty minutes or a half an hour. Only a reboot will bring it back to life. Let me make this clear; do NOT put in a net route, with the same address as your default route, under TCP/IP 4.1 or you will have troubles! It will cause a catastrophic vacuum at the Earth's core and all life as we know it will come to a screeching, sudden halt! Remember; I warned you here first!It's not good to come crying to me after the world has been destroyed! I simply will not be there for you.

At this point it is important to go through the TCP/IP Configuration Notebook page by page with a similar attention to detail as I did with the Network Installation program in Part II of this article. To that end I will start on page one of the notebook.


A lot of the following configurations have all ready been done during the installation. It is put here for those of you that have installed their NICs prior to reading this article and for troubleshooting any errors that you may find yourself with after Parts I and II.

Configure Network Interface Parameters

Under "Interface to Configure" you will see a list of LAN Interfaces;

[click to view enlarged graphic]

Essentially LAN 0 is the first NIC that you have in your machine. If you have only one then this is it. Select LAN Interface 0 and go to "Configuration Options." Enable interface and manually add the address you wish to use for this adapter. This may or may not be your internal LAN connection. (Which adapter is LAN 0 can be determine for sure during the boot process). Subnet mask will typically be unless you know other wise.

Next select Loopback Interface under "Interface to Configure". Please note this must be selected and set to IP address with subnet mask or you're going to have troubles. Essentially, this allows your machine to recognize and talk to itself. It will also allow you to use TCP/IP applications if you don't have a NIC installed in your machine. Sort of like a software NIC but not really. You know like a soft-serve ice cream is like hard-server ice but not really... or like Bill Gates is like the devil but not really... or... what a minute! Hmm...

Under advanced options leave all as is. One thing to note is that MTU, (Maximum Transmission Unit), is typically set to 1500 which is the maximum. Some people claim you're better off setting it to 1499 if you experience slowdowns in transmission speeds. Either way, unless you're experiencing problems, you won't see any practical difference between the two. The rest of the advanced settings, unless you have a specific need to change them, leave as is.

[click to view enlarged graphic]

[click to view enlarged graphic]

Configure Routing Information

Create a "Default Route" here. It will be the IP address of your Internet connection that your ISP has given you to bind to, (read "use with"), your NIC. In most circumstances, after you enter this, it will automatically create a "Net Route" for you as well.

[click to view enlarged graphic]


The net entry is added automatically as the dial-up connection, (when used with TCP/IP on a LAN at the same time), overwrites your "Default Route" when put to use.

Remember if you are using TCP/IP 4.1 Delete the "Net Route" that is created here. 4.0 users leave as is and add a "Net Route" for all other machines in your LAN. 4.1 users need add nothing else.

Everyone turn on "IP Forwarding" if you want any other machines on the LAN to have Internet access. It need only be activated on the machine that has the modem and not on any other machine. There is one caveat to turning this on; there is the possibility that someone on the Internet can gain access to some of your resources. I've never heard of such a thing happening but there is a slight reduction in security that could allow this to happen. However, there isn't any real choice if you want all the machines on your LAN to have Internet access.

Of course you 4.0 users, you can argue that if we aren't using a dial-up connection that you won't need to put the "Net Route" in in addition to the "Default Route"... experience has told me that it works smoother if you do.

NOTE for 4.0 Users:

Technically speaking there is no need to add another "Net Route" for every machine on your LAN. I have read conflicting information some saying put them in and others saying no need. I say "need!"

Configure Name Resolution Services

After "This Computers Host Name" you will enter the name that you want to use for this computer; I.E.: the one that has the cable modem. "Local Domain Name" serves no real purpose to the content of this article... leave it blank.

[click to view enlarged graphic]

Now, under "LAN Name Server Configuration" you will have to enter all the DNS, (Domain Name Server), IP addresses that your ISP has given you.


You MUST enter IP address here do not use a domain name.(I.E.: do not use www.mydns.com)

Have the recommended one be first on the list under "Name Server Addresses". "Lan Domain Search List" stays empty.

Configure Hosts Information

"Look Through Hosts List Before Going To Name Server" should be checked. This will ever-so-slightly speed up access to local machines by searching for a requested system that matches the name. If, after doing this, you go to a command prompt and try to ping one of the Host names typed in here, (instead of using the klutzy IP address) it will go to the Host list that this generates, look up the IP address of the requested host and ping it for you as if you had typed in the IP address. Of course, you can also use Host names with other things like telnet, ftp, etc. Neat what?

[click here for enlarged graphic]


If you don't check "Look Through Hosts List Before Going To Name Server" first, then the system will first check with the DNS for the requested name.

All entries here are stored in the HOSTS file and are kept in X:\MPTN\ETC\ directory. It can easily be edited with any text editor. Dragon says: "Always remember to backup before you make any changes!" 8)

Of course there are more areas on the TCP/IP Configuration Notebook but they are not relevant to this article so we will close the notebook here.

Next week we will go onto the configuration of the other clients, (including Windows), for sure, and deal with the installation of firewalling software if time allows. For now always remember that proper black, nylon, silky stocking should always be held up with a matching garter and can, in an emergency, be used to replace a broken fan belt in your car. Good-day!

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