3Com Router User Manual

4
TERMINAL SERVICE
This chapter includes information on the following topics:
■Terminal Service Overview
■Terminal Message Service
■Dumb Terminal Service
■Terminal Service of Telnet Connection
■Rlogin Terminal Service
■X.25 PAD Remote Access Service
Terminal Service 
OverviewThe terminal services provided by the 3Com Router to access the command line 
interface are as follows:
■Perform terminal configuration via Console port
■Perform terminal configuration via asynchronous serial port
■Perform terminal...

58CHAPTER 4: TERMINAL SERVICE
Features of Terminal 
Service at Async Serial 
PortThe 3Com Router supports remote configuration on the router via asynchronous 
serial port (including synchronous/asynchronous serial port, 8/16 asynchronous 
serial port, and AUX port). Please refer to 
Chapter 2 “3Com Router User 
Interface”of this manual for the specific method to establish the configuration 
environment.
The remote terminal service features of the asynchronous serial port are shown in 
the following...

Terminal Message Service59
with user B, user A should telnet onto Router B and execute the send command to 
send the related information in all views. Then user B can receive the “message” 
sent from user A. If user B does not want to receive additional similar messages, 
they can use the 
send switch command to disable the function of receiving 
messages.
Configure Terminal 
Message ServiceTerminal message service configuration includes:
■Send message to terminals
■Enable/disable receiving messages from...

60CHAPTER 4: TERMINAL SERVICE
Typical Example of 
Terminal Message 
Service Configuration#  Input the send command in system view.
[Router] send
Enter message, end with CTRL/Z; abort with CTRL/C:
#  Input the contents of the message that the terminal will send.
hello world #  (Enter  to terminate the message input )
end message? [confirm]
Press Enter, Ctrl+W, y, or Y to confirm the sending. Press Ctrl+C or other characters 
to give up the sending.
Dumb Terminal 
Service When the asynchronous serial port...

Dumb Terminal Service61
By default, no dumb terminal service is configured.
2Configure auto-execute command command
If the auto-execute command command is configured on the asynchronous serial 
interface, when you press Enter twice on the external terminal connected to the 
interface or log onto the router in modem dial-up mode and press Enter twice, the 
router will automatically execute the operation preset by the 
auto-execute 
command
 command.
If the router is configured with the auto-execute...

62CHAPTER 4: TERMINAL SERVICE
Figure 27   Dumb terminal networking diagram
1Configure the interface to dumb terminal mode. 
[Router-Serial1] physical-mode async
[Router-Serial1] undo modem
[Router-Serial1] async mode flow
2Configure the auto-execute command command.
[Router-Serial1] auto-execute command telnet 10.110.164.45
After the configuration, press Enter twice on the terminal connected to this async 
interface to log on the SCO UNIX host 1.110.164.45. During the configuration, 
you can click exit...

Terminal Service of Telnet Connection63
Figure 29   Telnet client service
Reverse Telnet OverviewReverse Telnet service: the user logs on the router with a specified port number by 
running the Telnet client program on the PC. Then the connection to the serial 
port device connected with the async port of the router is established. One 
example: the 3Com Router performs remote configuration and maintenance of 
the external devices connected with its 8/16 asynchronous port with Reverse 
Telnet service....

64CHAPTER 4: TERMINAL SERVICE
Ta b l e 46   Establish Telnet Server or Telnet Client connection
By default, Telnet Server starts automatically. The default value of service-port is 
23.
To terminate Telnet service, enter Ctrl+] at Telnet Client side.
Setup Reverse Telnet Connection
Please use async mode flow and undo modem commands in asynchronous 
interface view, use 
telnet and terminal telnet refuse-negotiation 
commands in system view, use 
reverse-telnet disconnect, reverse-telnet 
timeout
,...

Terminal Service of Telnet Connection65
The interface listen port number is within the range of 1025 to 65535. Please note 
that the listen port number cannot be the same as that of the widely used ports. 
By default, the port number and asynchronous interface have the following 
relations:
■The async serial interface number starts from 2001. For instance, the first async 
serial interface number is 2001, the second is 2002, and so on.
■The AUX interface number is 3000. 
■The sync serial interface number...

66CHAPTER 4: TERMINAL SERVICE
Password: 
User guest logged in . 
3The message showing successful Telnet to Router B should pop up and display the 
host name of RouterB.
[RouterB]
Example of Reverse Telnet
The host is connected to the router, then communicates with the device 
connected to the seventh asynchronous serial interface of the router. The IP 
address of the router is 10.110.164.44.
[Router] telnet 10.110.164.44 2007
Trying  10.110.164.44...
Service port is 2007 (tty)
Connected to 10.110.164.44...