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ME60 Troubleshooting Guide V1.0 (VRPv8)

This document provides the maintenance guide of the device, including daily maintenance, emergence maintenance, and typical troubleshooting.
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Telnet Troubleshooting

Telnet Troubleshooting

This chapter describes common causes of the fault that the user fails to log in to the server through Telnet, and provides the corresponding troubleshooting flowcharts and examples.

A User Fails to Log in to a Server Using Telnet

This section describes the troubleshooting flowchart and provides a step-by-step troubleshooting procedure for the fault that the user fails to log in to the server using Telnet.

Common Causes

This user login failure is commonly caused by one of the following:

  • The route between a client and server is unreachable, as a result, the TCP connection between the client and server cannot be established.
  • The number of users logging in to the server has reached the upper threshold.
  • An ACL with a deny rule is configured in the VTY user interface view.
  • The access protocol specified in the VTY user interface view is incorrect. For example, when the access protocol is set to SSH using the protocol inbound command, the user cannot log in to the server using Telnet.
Troubleshooting Flowchart

Figure 4-6 shows the troubleshooting flowchart.

Figure 4-6 Troubleshooting flowchart for the fault that the client fails to log in to the server using Telnet

Troubleshooting Procedure

Context

NOTE:

After the commands are configured to troubleshoot the faults, check the configuration validation mode to ensure that the configurations take effect. Unless otherwise specified, this manual defaults to immediate validation mode.

  • In immediate validation mode, the configurations take effect after the commands are entered.
  • In two-phase validation mode, after the commands are configured, the commit command needs to be run to commit the configurations.

Save the results of each troubleshooting step so that if your troubleshooting attempts fail to correct the fault, you will have a record of your actions to present to Huawei.

Procedure

  1. Check whether the Telnet client can ping the server.

    Run the ping command to check network connectivity. If the ping fails, the Telnet connection cannot be established between the client and server.

    If the ping fails, see The Ping Operation Fails to locate the problem so that the Telnet client can ping the server.

  2. Check whether the number of users logging in to the server has reached the upper threshold.

    Log in to the server using a console interface and run the display users command to check whether all the available VTY channels are used. By default, a maximum of 5 users can log in to the server through VTY channels.

    <HUAWEI> display user-interface maximum-vty
     Maximum of VTY user:5
    <HUAWEI> display users
      User-Intf    Delay    Type   Network Address     AuthenStatus    AuthorcmdFlag
    + 0   CON 0   00:00:01                                                          Username : Unspecified
      34  VTY 0   02:11:28  TEL    10.138.81.61        pass            yes          Username : huawei

    If the number of users logging in to the server has reached the upper threshold, run the user-interface maximum-vty vty-number command to increase the maximum number of users allowed to log in to the server through VTY channels to 18.

    <HUAWEI> system-view
    [~HUAWEI] user-interface maximum-vty 18

  3. Check whether an ACL with a deny rule is configured in the VTY user interface view.

    If an ACL rule has already been bound to VTY user interfaces, verify that the configured ACL rule does not deny IP addresses, port numbers, or protocol numbers of clients.

  4. Check whether the access protocol configured in the VTY user interface view is correct.

    [~HUAWEI] user-interface vty 0 4
    [~HUAWEI-ui-vty0-4] display this
    user-interface vty 0 4
     authentication-mode aaa
     user privilege level 3
     idle-timeout 0 0
     protocol inbound ssh
    Run the protocol inbound { all | ssh | telnet } command to configure the user access protocol. Telnet is an insecure protocol. SSH is recommended.
    • If the user access protocol is set to SSH, the user cannot log in to the server using Telnet.
    • If the user access protocol is set to "all", the user can log in to the server using Telnet or SSH.

  5. Check whether the authentication mode is configured in the user interface view.

    • If the authentication-mode password command is run, the login authentication mode in the VTY channel is set to password.

    • If the authentication-mode aaa command is run, the login authentication mode is set to aaa. You must run the local-user password command to add a local user.

  6. Collect the following information and contact Huawei technical support personnel.

    • Results of the preceding troubleshooting procedures.
    • Configuration files, log files, and alarm files of the devices.

Relevant Alarms and Logs
Relevant Alarms

None.

Relevant Logs

None.

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Updated: 2019-06-11

Document ID: EDOC1000175918

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