By using a Telnet client via the Telnet protocol, you can connect to the SAP NetWeaver Application Server and administer it using a predefined set of shell commands.
A connection can be established if the AS Java system is installed and running, and the machine has a Telnet client through which a connection to the server can be established.
Communication over Telnet is not encrypted. For security reasons, access to the AS Java over Telnet is limited to host 127.0.0.1 (localhost).
1. Check the Telnet port on which you can connect to the application server.
More information: Viewing and Configuring the Communication Ports
2. Run a Telnet client and connect to the local system by specifying localhost and the Telnet port. Once a connection is established, the Telnet administration console of the application server is opened.
Alternatively, you can open a Telnet client from the SAP MC:
i. Select the local SAP system on which you want to start Telnet.
ii. Browse to the Process Table node.
iii. In the right-hand pane, select the ICM and choose Telnet from the context menu.
The Telnet administration console of the application server is opened.
3. Enter valid login info (user name and password) to authenticate yourself.
If the input information is incorrect, the link is disconnected and the console disappears. You must then complete the above steps again to open a new Telnet console.
If your connection is successful, the console remains open, you are logged on to one of the server processes in the instance, and you can start your administration.
4. Use the LSC command to display all server processes with their ID, name, host, port, state, and so on. The first component displayed is the one you are currently administering.
5. To switch from one server process to another use the JUMP shell command and specify the server process’s ID as a parameter. For example, executing JUMP 8931750 enables remote administration of a server process with ID 8931750.
If you have only one server process configured in your instance, you are already connected to it and the JUMPcommand will display a message that you are already administering the current server process.
The application server has a predefined set of shell commands grouped according to the functions they provide. To use the shell commands from a group, you first have to activate that group by adding it to the shell environment. By default, only the ADMIN, SYSTEM, DEPLOY, and TELNET groups are activated due to their vital importance.
1. To view the names of all available groups of shell commands (both activated and not activated), execute the MAN -g command.
2. To add a group of shell commands to the shell environment, enter ADD [groupName] in the command line. The groupName parameter is the name of the group of shell commands to be added.
3. To view all activated groups and their shell commands, execute the MAN command.
4. To view the help message for a shell command, execute MAN and the command name in the command line. For example MAN ADD displays the help message of the ADD command.
The conventions used in the help messages are as follows:
■ The brackets encompassing the shell command parameters have a special meaning explained below. There is no need to type them when executing a command on the command line, unless it is indicated explicitly in the corresponding command description.
● The <> type of brackets means that the parameter is required. If this parameter is not specified when executing the shell command, the command displays the help message.
● The  type of brackets means that the parameter is optional.
LISTPROPS [clusterID] <serviceName>
where [clusterID] is optional, and <serviceName> is required.
■ The commands are displayed in capital letters – for example, LISTPROPS; however, you do not have to type them in capital letters in the command line. The shell language is case-insensitive.
■ When a shell command has an abbreviated alternative, it is given in () (brackets) after the command name. For example
■ If the parameters of a shell command contain key words, when executing the shell command, you must specify the key words exactly as they are given in the command syntax. That is, you must not replace the key words with other values. Key words are identified by the - (hyphen), with which they begin.
Execute the EXIT command in the command line.
A security role telnet_login in the security policy configuration (called service.telnet) manages access restrictions when using Telnet. Only users that are in this security role are permitted to connect to the cluster using Telnet. By default, all administrator users can use Telnet. Access restrictions can be changed using the interfaces of the security roles.
Do not allow users that are not administrators to use Telnet.