Introduction of Telnet
Configure Win 2000 Telnet Service to Not Require NTLM
Connection to host lost
Starting the Telnet Service
Using the Telnet Service
Using Telnet Server Service Administration
Use Telnet to Test an Internet Mail Connection
Use Telnet to test Terminal Server

Introduction of Telnet

The Telnet is another popular remote control tool that allows a Telnet client to connect across a network and access a command session. You can us it for logging on to remote computers over a LAN or the Internet. Using Telnet protocol, you can contact the remote host by using either the name or IP like 192.168.1.1.

If you are attempting to use Telnet to connect to a member server that is using basic security, you must have permissions to log on to the local computer. If the server is using challenge/response (NTLM) security, then you simply logon to the server from the network (as you do in a file share). The basic Telnet client for Windows NT does not support the NTLM feature.

NOTE: To use a GUI-based Telnet client on a Windows 2000-based computer, obtain a copy of the Telnet.exe file from a Windows NT 4.0-based computer, rename it to Telnet32.exe, and then copy it to the Windows 2000-based computer. Telnet.exe is located in the C:\Winnt\System32 folder. Telnet for Windows 2000 does not have a Graphical User Interface (GUI).

Configure Win 2000 Telnet Service to Not Require NTLM

By default, the Win 2000 Telnet service requires NTLM authentication. However, if Win 2000 is configured to use Kerberos as its default authentication method, then Telnet users are not able to obtain access to domain/AD resources including network validation. To configure the Win 2000 Telnet Service to not require NTLM, run Telnet Server Administration, select option 3, Display / change registry settings and then select option 7, NTLM. Change the default setting from 2 to 0 to disable the NTLM requirement.

Connection to host lost

Symptoms: when attempting to telnet a remote computer, you may receive "Connection to host lost" message.

Resolutions: 1. make sure the telnet service is running.
2. check the security such as belonging to telnetclients group, NTLM authentication and logon locally.
3. No firewall and Proxy running on client.

Starting the Telnet Service

To use telnet, you must start the telnet service on the remote host. By default, the Telnet service startup type is set to Manual when you install Wi2K/XP.

To tart the Telnet Service manually, 1) use net start telnet command; 2) go to Start>Programs>Administrative Tools>Telnet Server Administration, at the command prompt, type 4 to start the Telnet service; 3) go to Start>Programs>Administrative Tools>Services>Telnet service, and then click Start.

To start the Telnet Service automatically, go to Start>Programs>Administrative Tools>Services>Telnet service, right-click Properties and select Automatic on Startup type box.

Using the Telnet Service

To connect a host by using the Telnet service, type the following command telnet ip_address/server_name (where ip_address is the host's IP address and server_name is the host's name). NOTE: By default, the server uses NTLM authentication and will prompt for a user name and password.

Using Telnet Server Service Administration

The Telnet Server Service Administration tool includes options that you can use to start, stop, or get information about the Windows 2000 Telnet Server service. You can get a list of current users, terminate a user's session, and change Telnet registry settings. To run the tool, type tlntadmn.exe in command prompt, and then click OK, or go to Start>Programs>Administrative Tools>Telnet Server Administration.

Use Telnet to Test an Internet Mail Connection

Use telnet mail server name or IP 110 to test POP. You should get +OK Microsoft Exchange 2000 POP3 server...ready. Otherwise, you get Connection failed. Use telnet mail server name or IP 25 to test SMTP. You should get 220 mail.domain.com... ready response.  Otherwise, you get Connection failed.

Use Telnet to test Terminal Server

If a TS client connect to TS through a firewall or router, you must open TCP port 3389. To test the port is opened or not, you can use telnet host name or ip 3389. If the test is successful, you will receive the telnet screen and a cursor. If not, you will get Connection failed message.

Use telnet to test XP Firewall

If you enable ICS feature in Windows XP, you should be able to test it by using  telnet host name or ip 389. If the test is successful, you will receive the telnet screen and a cursor. If not, you will get Connection failed message

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