Telnet Servers and File Transfer

Telnet Servers for Windows

Use version 5.1 or later of tlntsvr.exe (generally found on Win2003, WinXP and later systems, in the WinNT\system32 directory). [To read a file's version number right click on the file in Windows Explorer, select "Properties", then the "Version" tab .] Version 5.1 and later can be configured for stream-mode operation and will work successfully to transfer files. Earlier versions of this MS native Telnet Server operate only in console-mode, sending one window of data at a time. In this mode the same data is sent more than once, along with extraneous cursor control characters, making it unusuitable for transferring files via telnet. Replace such a server by downloading and installing the telnet server in the "Services for UNIX, version 3.5" package from Microsoft.

This package can be downloaded without charge from the Microsoft website, or may be obtained on CD-ROM. Go to http://www.microsoft.com/windows/sfu or search for a download titled "Services for UNIX" at http://msdn.microsoft.com. Run the 200+ Mb executeable to self-extract it. Run its msi installer, choosing 'custom installation' and unselect all items except 'Remote Connectivity'. (Unselect the 'Windows remote shell' component under 'Remote Connectivity'.) Complete the installation. Note: The telnet server components, tlntsvr.exe and tlntsess.exe are protected by the Windows File Protection system on Windows 2000 and later systems, so cannot be installed by simply replacing the earlier version components with the later ones. They must be installed with a Windows installer which circumvents Windows File Protection for these components during setup.

The telnet server component from the "Services for UNIX" package can also be installed from the command line, and includes an unattended remote installation option. Follow the instructions provided in the file install.htm in the top level directory of "Services...".

In some cases the required file tnadmin.exe from the unzipped sfu\telnet sub-directory may not be installed into the system32 directory during setup. In this case simply move a copy of this file directly into the ...system32 directory. A direct copy is possible in this case as it is not covered by Window File Protection. Then run tnadmin from the command line to configure the server: Set the port number as desired, the telnet server mode to stream mode (value = 2) and the authentication method as desired. Start or restart the server to pickup these new configuration values using the tnadmin command, the services window in the control panel, or the "net start tlntsvr" command at the command line.

If you get a message like "session startup failed. Shell may have failed to initialize" and the Event Appplications tlntsvr log gives a message indicating that it can't find cmd.exe, fix the default shell registry entry for the server by changing %systemroot%\system32\cmd.exe to cmd.exe. Some old versions may use the full path, whereas the newer one doesn't and assumes system32 instead. In some installation scenarios this key does not get updated properly during setup. The registry entries are at HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\TelnetServer\1.0

This telnet server is labeled version 8.0, although functionally it is nearly identical to version 5.1

This telnet server, even in stream-mode, will not relay a telnet session. If you need to relay Courier data collection through a WinNT system use the compatible server and client set supplied with NEPM or an equivalent third party set.

Telnet Servers on other systems.

Native Telnet servers and clients on all other system types generally operate satisfactorily in stream mode and will relay without any special requirements.