Microsoft TCP/IP

Chapter 14

Connectivity in Heterogeneous Environments

In this lesson we'll cover how to connect to "foreign" (UNIX) hosts, how to connect to TCP/IP Printers, and how to configure and use FTP software.

Connectivity in Heterogeneous Environments

What we're talking about here, in terms of "heterogeneous" is dealing with a mix of NetBIOS and UNIX host computers. We've seen that name resolution is quite different between the two.

TCP/IP allows us to connect to all sorts of different host computers, such as:

Þ OS/2

Þ UNIX

Þ Solaris (Sun Microsystems)

Þ VMS

As long as the applications on both ends of the communications link as able to use TCP/IP, then there is no problem with working together with these foreign hosts. In fact, if you have experience with the Internet, you are working with foreign hosts all the time, because the majority of computers you connect to via the Internet are UNIX based computers. It is TCP/IP which makes the connection transparent to the user.

Recall that in order to make Microsoft Networking commands work properly, we have two requirements:

1. Both computers must use the same transport driver

2. Both computers must be able to utilize SMB (system message block)
The workstation service communicates with an SMB server process at the remote host. SMB is the file sharing protocol used on all Microsoft networks.

Connecting to Windows NT Server from a Remote Host

So, a WinNT computer is able to offer file servers (make file available to) Microsoft clients via the SMB protocol. We can make files available to UNIX clients by using the network file system (NFS) protocol or the FTP service or by installing an SMB client service on the UNIX client system.

You can buy third party file server software for WinNT Server. This software will provide NFS server support for both Microsoft and non Microsoft (UNIX) clients. These also provide support for FAT, CDFS, NTFS and HPFS as well.

TCP/IP Utilities

One of the really cool things about TCP/IP is all the utilities that are available that you can use to manipulate files and computers as well as using them to diagnose and treat your network.

TCP/IP utility	Function
REXEC	Allows you to run a program on a remote computer and offers password based security
RSH (Remote Shell)	Allows you to execute commands on a remote server without having to log in. NO password protection
Telnet	Provides Terminal Emulation (dumb terminal) and allows for user and password authentication
RCP (Remote Copy)	Allows copying files from NT to a remote RCP host running the RCP daemon service. NO password or user authentication
FTP	File Transfer Protocol. Allows uploading and downloading of files between computers that having FTP host and FTP Services running. User and password authentication available
TFTP	Subset of FTP. Uses UDP rather than TCP. Server must be running TFTP Server software. NO users authentication provided
Web Browser	See web pages
LPD	Line Print Daemon. Allows users to submit print jobs to TCP printers and allows for user and password authentication. The LPD is the server side of the TCP/IP print process
LPR	Line Print Request. This is the client side of TCP/IP Printing. LPR allows the user to submit printing requests to the LPD host
LPQ	Line Print Request. Allows users to request status of their documents sent to a TCP/IP printer.

Remote Execution Utilities

REXEC

This allow remote execution of commands with authentication based on user names and passwords.

RSH

Allows you to run commands on remote server running the RSH daemon. You don't have to log on to use this; so, you can actually run commands without loggin on. You do have to enter a user name, and as long as that username is in a .rhosts file, you can get on.

Telnet

The Telnet program provides a "dumb terminal" access to another server. You can run programs on a remote server via Telnet. Think of it as a PCAnywhere for UNIX. The client must have Telnet software and the Server must be running Telnet Server software. NT comes with Telnet client software, but you must go to a third party to get Telnet Server software.

Data Transfer Utilities

RCP

RCP (remote copy protocol) does not require the user to log on. The server must be running RCP Server software. You don't have to log on, but you will be asked for a name, which must be included in a .rhosts file. You can copy files between a local and a remote host, or between two remote hosts. You are never asked for a password.

FTP

FTP allows you move files across computers that are running the FTP client and FTP server software. You can provide for username and password access. FTP uses TCP as its transport protocol. FTP servers are popular on the Internet for downloading files between FTP is faster than HTTP in the file transfer process. FTP allows for anonymous access, so the user does not have to be authenticated if they are using anonymous access.

FTP Commands

Command	Function
Binary	Changes the file transfer type to binary
Get	Copies a remote file to a local host
Put	Copies a local file to a remote host
!	Temporarily returns the user to the command prompt
Quit or bye	Exits FTP

TFTP

TFTP is similar to FTP in that it is used to transfer files between computers. However, TFTP uses UDP rather than TCP as its transfer protocol. NT contains only the TFTP software; if you want to use TFTP on a server, you must use a third party product.

Printing Utilities

You can configuring a printer in Windows NT so that UNIX hosts can connect to it via the LPR request method. You do this in NT by installing the TCP/IP printing services. Windows NT clients can also connect to a TCP/IP printer using the Print Manager, without having to go through the process of issuing a LPR request like the UNIX clients must do.

There are three TCP/IP printing utilities:

1. LPD, which runs as a service. This enables any client to use the LPR command to request printing to the TCP/IP printer

2. LPR. Allows any computer with the LPR program to send a print request to a LPD print server

3. LPQ. The LPQ utility allows a user to query the TCP/IP printer to assess the status of their print job.

Using the TCP/IP Print Server (LPD)

For NT Server to accept requests from LPR clients, the print server must have the LPD service installed.

Using LPR and LPQ

How you use a TCP/IP printer is dependent on how you're accessing it:

1. From a Windows based application, you use the Print Manager like normally.

2. From both a Windows based or UNIX application, you use a command line argument using the LPR.exe utility

To submit a job:

lpr -Sip_address -Pprinter_name filename

Print jobs are submitted via port 512 to 1024

Checking the Print Status (LPQ)

You use the LPR utility to check the status of your print jobs. In order to find the status of your print jobs, you can issue the following command from the command line:

lpq -Sip_address -Pprinter_name -l

The -S and -P switches must be capitalized. The -l switch can be either upper for lower case.

Using Windows NT as a Print Gateway

When an NT computer is running the LPD service, it can provide gateway services in the following matter:

1. A computer running NT with the TCP/IP print services can receive print jobs from Microsoft clients and then forward them automatically to a TCP/IP based print server running LPD. In this case, the client does NOT require LPR or TCP/IP. The Print server is a UNIX machine in this case, so the client computers don't need client software installed on them in order to print to this UNIX print server. You just send the job to the NT Server Gateway, and it forwards it to the UNIX print server

2. An NT computer running the TCP/IP print services can receive print jobs from any LPR client, and forward them to any printer visible to the computer running NT. This includes UNIX hosts, so that the UNIX hosts don't need special client software to connect to the printer.