Using the Telnet Protocol in a BANDIT Product

Transcription

1 encor! enetworks TM Version A.1, March Encore Networks, Inc. All rights reserved. Using the Telnet Protocol in a BANDIT Product Telnet is an asynchronous protocol over IP. A BANDIT device s Telnet feature provides a way for the unit to connect a standard asynchronous terminal to an IP network using the Telnet protocol over TCP. A Telnet port can be configured as a server or a client, answering or issuing calls, respectively. Calls can be issued automatically to a fixed address or manually to any IP Address. Figure 2-1 shows the DTE/DCE control of the physical filter. The physical filter maps the physical port control signals to their logical counterparts in the logical filter. In effect, this process acts as a software multiplexer for modem control signals. The logical filter allows you to use the Telnet Menu options to gain better control over the port control signals. The default for Local TCP Port is 256 plus the port number. Phys DSR Phys DCD DCE DTE DCE DTE Logical DSR Logical DCD Forced DSR On YES ON NO Forced DCD On YES ON NO Connection Indication DCD/ DSR Phys DTR Phys RTS Phys CTS DB-25 DCE DTE DCE DTE DCE DTE Physical Filter Logical DTR Logical RTS Logical CTS ON Forced DTR On NO YES Logical Filter Connection Enable Logical RTS Logical CTS DTR RTS CTS Telnet Module Hardware Software Figure 2-1. Telnet Logical Diagram The modem control signal options are designed to enhance the use of the DTR, DCD, and DSR signals. These options are not necessary under normal circumstances. However, any of these For information on trademarks, safety, limitations of liability, and similar topics, see Notices. Home Module: Software Management Document 2

2 Page 2 Software Management, Document 2 signals can be forced On if needed to facilitate the use of Telnet. For instance, it is advantageous to force control signals On if a terminal device is not capable of providing the necessary controls to the Telnet module. 2.1 Telnet Applications There are many different uses for the Telnet feature. Several applications are described below. Note: In these examples, when the Answer Mode is on, the unit is referred to as a Telnet Server. Any unit port configured for Telnet is a Telnet Client when the Answer Mode is off Local to Remote Server Connection Several terminals can be connected to a remote Telnet Server via a Telnet session. Each terminal connects to a separate unit user port configured for Telnet. These unit ports act as Telnet Clients that are capable of pinging the remote server. Frame Relay Server EtherFRAD BANDIT Telnet Client EtherFRAD BANDIT or Other or Router Figure 2-2. Local to Remote Server Computer to Remote Printer Connection Telnet can be used to send print jobs to remote printers. The unit port connected to the printer acts as a Telnet Server for this application. It provides flow control and error free communications using TCP/IP.

3 Using the Telnet Protocol in a BANDIT Product Page 3 Frame Relay Telnet Server Computer (Client) Printer MonoFRAD BANDIT Data Router Figure 2-3. Computer to Remote Printer Local to Local Server on Different Ports The unit can provide a Telnet session between a local terminal connected to one of its user ports and a local server connected to another of its user ports or its Ethernet port. The port connected to the terminal must be configured for Telnet. The local terminal is capable of pinging the local server. Frame Relay Telnet Client EtherFRAD BANDIT Server Figure 2-4. Local to Local Server Local to Local Supervisor Port A terminal connected to a unit user port configured as a Telnet can access the Supervisory function of that unit. This allows users to configure the unit from their local Telnet terminals. The local terminal can also ping the unit.

4 Page 4 Software Management, Document 2 Telnet Server EtherFRAD BANDIT Figure 2-5. Local to Local Supervisor Port Local to Remote BANDIT Supervisor Port A terminal connected to a local unit user port configured as a Telnet can establish a Telnet session to the Supervisor port of a remote unit. This enables the local terminal to configure the remote unit. The local terminal can also ping the remote unit. Frame Relay EtherFRAD BANDIT 1 N 2 Telnet Client EtherFRAD BANDIT N 1 Telnet Client Figure 2-6. Local to Remote BANDIT Supervisor Port Local to Remote A local terminal can be connected to a remote terminal using a Telnet session. In this case, the local unit port must be configured as a Telnet and the remote unit port as a Telnet with the Answer Mode On. This, in effect, provides reliable end-to-end async communication. Frame Relay EtherFRAD BANDIT 1 N 2 Telnet Client EtherFRAD BANDIT N 1 Telnet Client Figure 2-7. Local to Remote

5 Using the Telnet Protocol in a BANDIT Product Page 5 It is important to remember that only one end can be configured to call the other. If both units are configured as Telnet s, one must have the Answer mode set to On. In addition, only one unit can be set for automatic dialing; the other unit must be set for Manual mode. 2.2 Using the Telnet Protocol to Communicate with the BANDIT The Telnet feature allows the unit to connect a standard asynchronous terminal or PC running terminal emulation software to an IP network, using the Telnet protocol over TCP/IP. Because Telnet uses TCP/IP, it automatically guarantees delivery of error free data. A Telnet port can be configured to answer Telnet calls (as a server) or issue Telnet calls (as a client), or both. Calls may be issued automatically to a fixed address or manually to any desired IP address. After you have configured a port to use the Telnet protocol, you can use a Telnet connection from a local or remote terminal to the BANDIT. To gain access to the unit Supervisor port via Telnet, you must establish a Telnet session between your terminal and the unit (i.e., Telnet to the IP address of the unit to be accessed). The unit may be configured from a remote site by establishing a Telnet session to it from a remote terminal. This provides access to the BANDIT s menus. In this mode, the unit acts as a Telnet server; the remote terminal is a client. A remote access password may be used to prevent unauthorized remote users from accessing the unit Configuring a BANDIT Port for the Telnet Protocol You can configure a serial port for the Telnet protocol. Note: In order for two units to interact properly as Telnet Server and Client, only one unit can be set up to call the other. Therefore: One unit must have Answer mode On. Only one unit can be set for automatic dialing. The other unit must be set for manual mode so the units can establish a connection. If both units are in the same mode (DTR Dial or Continuous), they will be attempting to call each other, and neither unit will answer. Note: All the parameters listed in the Telnet Parameters menu can also be accessed by a remote SNMP management station. See Using SNMP in the BANDIT Products. Note: Once a Telnet connection has been established, it can be broken by pressing CTRL X on the terminal at either end of the connection. If the Connection type has been set to Manual, the Telnet Commands Menu is refreshed after you press Enter. To exit Telnet mode, use CTRL E.

6 Page 6 Software Management, Document 2 How to Configure a Port to Use the Telnet Protocol Note: To successfully route data through the unit, you must complete the IP Routing Table (see Section 1.2, The Routing Menu). If you are using IP routing, you must also enter the local IP address (see Identifying the BANDIT Device in the Network). See Telnet Statistics for a description of the statistics used to monitor this protocol. 1 From the Main Menu, select Advanced Configurations >> Data Configurations >> a physical port >> Undefine Current Logical Port >> Protocol >> Telnet. Note: The Telnet protocol is available only on serial ports and on the Supervisory port. The Telnet Parameters menu is displayed. Telnet Parameters : SERIAL ) Speed : ) Data Bits : 8 3) Parity : None 4) Stop Bits : 1 5) Flow Control : OFF 6) Flow Control Type : RTS/CTS 7) Connection Type : Manual 8) Answer Mode : OFF 9) Data Mode : Normal A) Null Insertion Mode : Normal B) Exit Session Key : CTRL-X C) Menu Quiet Mode : OFF D) Local Echo : Auto E) Store and Forward : Auto F) Force DTR ON : No G) Force DCD ON : No H) Force DSR ON : No I) Local TCP Port : 257 J) Remote TCP Port : 0 K) Remote IP Address : L) XXXPAD Logical Port : N/A Enter Choice : Note: The menu does not show type because the Telnet protocol is always asynchronous. Note: Make sure the settings for speed, data bits, parity, and stop bits match the communications settings used by your terminal (or terminal emulator). 2 Select Speed to specify an asynchronous clock speed. The menu to Configure Asynchronous Clock Speed is displayed.

7 Using the Telnet Protocol in a BANDIT Product Page 7 Configure Asynchronous Clock Speed ) ) ) ) ) ) ) ) ) A) Enter Choice : Note: If the Supervisory port is redefined as a Telnet server from the Supervisory port, the Telnet port defaults to the current speed of the Supervisory port. However, if you define any other port for Telnet, or if you set the Supervisory port for Telnet from a remote Telnet session, the default speed is 9600 bps. 3 Select Data Bits to specify the number of data bits to be transmitted in each character. The menu to Configure Asynchronous Number of Data Bits is displayed. Configure Asynchronous Number of Data Bits ) 7 2) 8 Enter Choice: a Select the number of data bits to be transmitted in each character. The corresponding value is displayed on the screen. 4 Select Parity to select the type of parity to be used. The menu to Configure Asynchronous Parity is displayed. Configure Asynchronous Parity ) Odd 2) Even 3) Mark 4) Space 5) None Enter Choice: a Select the parity the connection will use. The corresponding parity is displayed on the screen.

8 Page 8 Software Management, Document 2 5 Select Stop Bits to indicate the number of stop bits. The menu to Configure Asynchronous Number of Stop Bits is displayed. Configure Asynchronous Number of Stop Bits ) 1 2) 2 Enter Choice: a Select the number of stop bits. The corresponding value is displayed on the screen. 6 Select Flow Control to set the flow control. It can be enabled for transmit only, for receive only, or for both directions. The menu to Configure Asynchronous Flow Control On or Off is displayed. Configure Asynchronous Flow Control ON / OFF ) Off 2) TX Only 3) RX Only 4) ON Enter Choice: a Enter the number of the item you want to select. The corresponding setting is displayed on the screen. 7 Select Flow Control Type. The menu to Configure Asynchronous Flow Control Type is displayed. Note: Both RTS/CTS hardware flow control and XON/XOFF software flow control are supported. Configure Asynchronous Flow Control Type ) RTS/CTS 2) XON/XOFF Enter Choice: a Select the type of flow control to use. The corresponding setting is displayed on the screen. 8 Select Connection Type to specify how the Telnet Client terminal initiates a connection with the Telnet Server. The following prompt is displayed.

9 Using the Telnet Protocol in a BANDIT Product Page 9 Enter Connection Type (M (Manual) or D (DTR Dial)): Note: You can select manual connection or DTR Dial. Observe the following: In the Manual mode, you must enter an IP Address to connect to a Telnet Server when you use the Telnet command on the System Administration menu. To end the Telnet session, press CTRL X. To exit Telnet mode, use CTRL E. You can also end the session from the remote end. The System Tools menu can be used to PING a remote Server. In the DTR Dial mode, Telnet initiates a Telnet connection to a remote Telnet Server immediately after the port s DTR is set. The remote TCP port and remote IP address configured in the Telnet Protocol menu are used to make the connection. The connection is closed when DTR is off. Note that DTR can be forced ON. Note: For two units to interact properly as Telnet Server and Client, only one unit can be set up to call the other. Therefore, only one unit can be set for automatic dialing. The other unit must be set for Manual mode for the units to establish a connection with each other. If both units are in the same mode (DTR Dial or Continuous mode), each will attempt to call the other, and neither unit will answer. a Select the connection type. 9 Select Answer Mode. This option allows you to set the port to act as a Telnet Server by turning on the Answer Mode. The following prompt is displayed. Enter Telnet Answer Mode (1 (OFF) or 2 (ON)): a Enter the number of the item you want to select. If the Answer Mode is On, the port responds to Telnet clients attempting to make a connection. If the Answer Mode is Off, the port does not answer Telnet calls. Note: For two units to interact properly as Telnet server and client, only one unit can be set up to call the other. Therefore, one unit must have the Answer mode set to On. Once a Telnet connection has been established, it can be broken by pressing CTRL x on the terminal at either end of the connection. If the Connection type has been set to Manual, the Telnet Commands Menu is refreshed after you press Enter. To exit Telnet mode, use CTRL E.

10 Page 10 Software Management, Document 2 10 Select Data Mode. This option allows you to set the Data Mode. There are two modes: normal and binary. The Normal data mode uses Ctrl x as an escape character. It allows parameter handshaking after connection. The binary data mode is in accordance with RFC 856. When in Binary Data mode, the only available method for dropping a connection is to drop the DTR control signal on either end of the connection. (Note that dropping DTR drops the connection in Normal mode as well.) The default for this parameter is Normal. The following menu is displayed: Configure Telnet Data Mode ) Normal 2) Binary Enter Choice: a Select a data mode. The Telnet Parameters Menu is redisplayed, with the Data Mode updated per your selection. 11 Select Null Insertion Mode to enable or disable the insertion or removal of null characters in the Telnet terminal protocol. The following menu options are displayed: Configure Telnet Null Insertion Mode ) Normal 2) Disable Enter Choice: Note: If you select Normal mode, null characters are added wherever needed to conform to standard telnet protocol. If you select Disable mode, null characters are not added. a Select the mode you want to use. 12 Select Exit Session Key to change the key combination used to cancel a telnet session. The following menu is displayed: Configure Telnet Exit Session Key ) CTRL-W 2) CTRL-X 3) CTRL-Y 4) CTRL-Z Enter Choice :

11 Using the Telnet Protocol in a BANDIT Product Page 11 a Select the key combination you want to use. 13 Select Menu Quiet Mode to disable this display. This capability is useful if a host machine or printer connected to the Telnet port does not tolerate the menu characters being received from the Telnet port. The default for this option is Off. When the Telnet Module Connection Type is configured as Manual and there is no active Telnet session on a given port, the Telnet Command Menu is displayed on the associated terminal. Configure Telnet Quiet Mode ) OFF 2) ON Enter Choice: Enter the number for OFF (1) or ON (2). a Select Off or On. The Telnet Parameters menu is redisplayed. 14 Select Local Echo. This option is a mechanism for displaying data that can be configured in the unit. The Local Echo option has three possible settings. You can enable, disable, or implement an automatic setting for the echo function. If it is Enabled, the unit always echoes characters received from the terminal back to the terminal. If Local Echo is Disabled, the unit does not echo received characters back to the terminal. When Local Echo is set to Auto, the unit echoes characters back to the local terminal only if the remote echo option has not been successfully negotiated between the local and remote Telnet modules (the unit is performing the Store and Forward option). The following prompt will be displayed: Enter Local Echo Mode (A (Auto), E (Enable) or D (Disable)): a Indicate the setting you want. The Telnet Parameters menu is redisplayed. 15 To control the negotiation of remote echoing and to select data forwarding methods, select Store and Forward. This option is directly linked to the Remote Echo function. The following prompt is displayed: Enter Store & Forward Mode (A (Auto), E (Enable) or D (Disable)): Remote Echo, or the Telnet Echo option, is a means for displaying data on the originating terminal screen by echoing it back from the remote host (see Figure 2-8).

12 Page 12 Software Management, Document 2 Unit Unit Frame Relay Local Telnet Remote Telnet Host Local Echo Remote Echo - Telnet Echo Option Local Telnet store & forward if remote echo option is not accepted Host may echo all or some of the characters received Figure 2-8. Local and Remote Echo Remote Echo not only provides a display of characters, but also allows data to be forwarded immediately from the local unit instead of being stored in a buffer and forwarded when Enter is pressed or the buffer limit (200 bytes) is reached. Either type of forwarding can be selected in the unit regardless of whether the host is set up to actually echo characters. In other words, the Store and Forward options determine the method for forwarding data from the terminal to the host regardless of whether a character display is returned to the terminal. The Remote Echo, or the Telnet Echo option, involves a negotiation between the terminal and host as to whether characters are echoed. The host configuration determines whether characters are echoed. At the same time, a negotiation between the units affects how data is handled. The Local unit requests the remote host, via the remote unit, to echo data back to the terminal. The Telnet module in the remote unit responds to the request as far as forwarding methods are concerned. This response is determined by the configured setting for Store and Forward. Both units must be configured the same way for the negotiation to be successful. If the negotiation is successful, data is forwarded immediately to the host upon receipt from the terminal. If the negotiation fails, data is stored and forwarded upon pressing Enter or when a buffer is full. There are three settings for this option. Auto: The unit attempts to negotiate the Telnet echo option and implements it if requested. If the negotiation fails, the unit stores and forwards data. If the negotiation succeeds, the unit forwards all data received from the local terminal immediately. Enabled: The unit attempts to negotiate the Telnet echo option and implement it if requested by the remote Telnet module. The unit forwards all received data immediately to the host even if the remote Telnet module refused the negotiation. Disabled: The unit does not attempt to negotiate the Telnet echo option and refuses to implement it even if the remote Telnet module requests it to do so. The unit always stores data from the local terminal until the Enter key is pressed or the buffer is filled, then forwards it to the host. a Select the mode you want.

13 Using the Telnet Protocol in a BANDIT Product Page 13 Note: This option supports both binary and ASCII (normal) data modes. If binary is being used, the Telnet function tries to negotiate a binary connection with the remote Telnet Server. If it is refused, the Telnet function reverts to using ASCII. In binary mode, the unit does not accept Ctrl x to disconnect the Telnet session. Only a change in the DTR port signal can disconnect the session. 16 Select Force DTR On. The following prompt is displayed: Force DTR ON (N (No) or Y (Yes)): Forcing a DTR signal on is useful if the terminal equipment connected to the unit port fails to supply DTR. This also prevents a Telnet session from being disconnected if DTR is dropped. a Enter the letter of the desired setting. The parameters menu will be redisplayed. 17 Select Force DCD On. The following prompt is displayed: Force DCD ON (N (No) or Y (Yes)): The Telnet module raises and lowers this control signal to indicate the connection status of its Telnet session. Forcing the signal On is useful if the varying DCD signal has a negative effect on the operation of the attached terminal. a Enter the letter of the desired setting. The parameters menu is redisplayed. 18 Select Force DSR On. The following prompt is displayed: Force DSR ON (N (No) or Y (Yes)): The Telnet module raises and lowers this control signal to indicate the connection status of its Telnet session. Forcing the signal On is useful if the varying DSR signal has a negative effect on the operation of the attached terminal. a Enter the letter of the desired setting. The parameters menu is redisplayed.

14 Page 14 Software Management, Document 2 19 Select Local TCP Port. The following prompt is displayed: Enter Local TCP port ( ): a Enter the port number and press <ENTER>. The Telnet Parameters menu is redisplayed. 20 Select Remote TCP Port. The following prompt is displayed: Enter Remote TCP port ( ): If you are using the DTR Dial or Continuous Connection Types, the number entered here is used to establish a Telnet session. If you are using the Manual Connection Type, you do not need to enter this number. a Enter the Remote TCP port number, and press <ENTER>. The Telnet Parameters menu is redisplayed. Note: The remote TCP port number and remote IP address together define a destination (socket). This information can be obtained from your Network Administrator. 21 Select Remote IP Address. The following prompt is displayed: Enter Remote IP Address (N.N.N.N) : If you are using the Data Ready (DTR) Dial or Continuous Connection Types, the value entered here is used to establish a Telnet session. If you are using the Manual Connection Type, you do not need to enter a value here. a Enter the IP address and press Enter. One of the following occurs: The Telnet Parameters menu is displayed again. If you have typed an address in the wrong format, the following message is displayed and you are returned to the Telnet Parameters menu. You can then select this option and try again.

15 Using the Telnet Protocol in a BANDIT Product Page 15 Invalid IP Address Entered 22 Select XXX PAD Logical Port to specify which logical port is configured for XXX PAD. The following prompt is displayed: Enter XXX PAD Logical Port : a Enter the number of the logical port configured (or to be configured) for XXX PAD, according to the XXX PAD Port Definition, and press <ENTER>. Note: If you configure a logical port for Telnet, you must configure another logical port for XXX PAD. (See Section 7.1, XXX PAD.) Note: To save the new configuration, you must write and reset the BANDIT. (See Section 3.6, Write Configuration, and Section 3.7, Reset Unit.) Opening a Telnet Session through the BANDIT Menus You can use the BANDIT menus to connect over the Telnet protocol. Note: To exit this type of Telnet session, press Ctrl E. 1 From the Main Menu, select System Administration >> Telnet. The following message is displayed. Entering Telnet. Press <Ctrl^E> to exit and return back to the Menus. 2 Press Enter. The Telnet Control Commands Menu is displayed. Table 2-1 describes the commands on this menu. Telnet Control Commands Telnet Remote Host ==> t <IP address> <TCP port> Ping Remote Host ==> p <IP address> Telnet Last ==> tl Ping Last ==> pl Exit ==> <Ctrl^E> >

16 Page 16 Software Management, Document 2 3 To return to the BANDIT menus after telnetting, press Ctrl E. Table 2-1. Telnet Control Commands Command Format Description t t a.b.c.d e (where a.b.c.d is the BANDIT s IP address Connects to the host with IP address a.b.c.d and TCP port e. and e is its TCP port) tl tl Connects to the host to which the terminal had previously been connected. p p a.b.c.d (where a.b.c.d is the BANDIT s IP address) Pings the host with IP address a.b.c.d. pl pl Pings the host that the terminal had previously pinged. Ctrl E Ctrl E Exits the Telnet session Telnet Control Commands Menu If you configure a BANDIT port for a Telnet connection (as described in How to Configure a Port to Use the Telnet Protocol), and you configure the Telnet Connection Type as manual (described in Step 8), and a session is not active on that port, the Telnet Control Commands Menu will be displayed when a terminal is connected to the port. (For example, if your console times out after you have configured and saved the Supervisory port s Telnet connection type as manual, you will see the Telnet Control Commands Menu when you press Enter.) ENCORE NETWORKS, INC. Telnet Control Commands Telnet Remote Host ==> t <IP address> <TCP port> Ping Remote Host ==> p <IP address> Telnet Last ==> tl Ping Last ==> pl > This menu can be used to establish Telnet sessions with a remote host or to ping a remote host. Table 2-1 describes the commands on this menu.

17 Using the Telnet Protocol in a BANDIT Product Page Establishing a Telnet Session To establish a Telnet session with a remote BANDIT, enter the connection command (t) and the remote socket (that is, the BANDIT s IP Address and TCP port) in the following format: t address port where address is the IP address and port is the TCP port. Note: To establish a Telnet session over the local BANDIT s Supervisory port, enter only the unit s IP Address. For example, to connect to the remote server with IP address , using TCP port 23, type the following: t Note: If the TCP port is not entered, the command assumes the default TCP port value 23, a port number often used for Telnet Servers. If you type an incorrect IP address, the following message is displayed. Verify the IP address and type the command again. Invalid IP Address If the remote socket information is valid, the following prompt is displayed while the connection is being attempted. If the remote socket is available, the Telnet session is established. Attempting Connection... (timeout period is 35 seconds) If the remote Telnet host has not responded within the time-out period, the following message is displayed. Press Enter to return to the Telnet Control Commands Menu. Telnet Connection Timeout Press ENTER for Main Menu Note: To connect with the same remote socket that you most recently used, simply type tl and press Enter.

18 Page 18 Software Management, Document Pinging a Telnet Server To ping a remote Telnet server, enter the ping command and remote IP address in the following format: p address where address is the server s IP address. A message is displayed, indicating elapsed time. If the ping is not successful, the following message is displayed. Timeout remote node did not respond to PING Note: To ping the same remote socket that you most recently pinged, simply type pl and press Enter.