Telnet Access over IPv6

The Telnet client and server in the Cisco software support IPv6 connections.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Prerequisites for Telnet Access over IPv6

To enable Telnet access over IPv6 to a device, you must create a vty interface and password.

Information About Telnet Access over IPv6

Telnet Access over IPv6

The Telnet client and server in Cisco software support IPv6 connections. A user can establish a Telnet session directly to the device using an IPv6 Telnet client, or an IPv6 Telnet connection can be initiated from the device. A vty interface and password must be created in order to enable Telnet access to an IPv6 device.

How to Enable Telnet Access over IPv6

Enabling Telnet Access to an IPv6 Device and Establishing a Telnet Session

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    ipv6 host name [port] ipv6-address

    4.    line [aux | console | tty | vty] line-number [ending-line-number]

    5.    password password

    6.    login [local | tacacs]

    7.    ipv6 access-class ipv6-access-list-name {in | out]

    8.    telnet host [port] [keyword]


DETAILED STEPS
      Command or Action Purpose
    Step 1 enable


    Example: 
    Device> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.
     
    Step 2 configure terminal


    Example: 
    Device# configure terminal
     

    Enters global configuration mode.

     
    Step 3 ipv6 host name [port] ipv6-address


    Example: 
    Device(config)# ipv6 host cisco-sj 2001:DB8:20:1::12
     

    Defines a static hostname-to-address mapping in the hostname cache.

     
    Step 4 line [aux | console | tty | vty] line-number [ending-line-number]


    Example: 
    Device(config)# line vty 0 4
     

    Creates a vty interface.

     
    Step 5 password password


    Example: 
    Device(config)# password hostword
     

    Creates a password that enables Telnet.

     
    Step 6 login [local | tacacs]


    Example: 
    Device(config)# login tacacs
     

    (Optional) Enables password checking at login.

     
    Step 7 ipv6 access-class ipv6-access-list-name {in | out]


    Example: 
    Device(config)# ipv6 access-list hostlist
     

    (Optional) Adds an IPv6 access list to the line interface.

    • Using this command restricts remote access to sessions that match the access list.
     
    Step 8 telnet host [port] [keyword]


    Example: 
    Device(config)# telnet cisco-sj
     

    Establishes a Telnet session from a device to a remote host using either the hostname or the IPv6 address.

    • The Telnet session can be established to a device name or to an IPv6 address.
     

    Configuration Examples for Telnet Access over IPv6

    Examples: Enabling Telnet Access to an IPv6 Device

    The following examples provide information on how to enable Telnet and start a session to or from an IPv6 device. In the following example, the IPv6 address is specified as 2001:DB8:20:1::12, and the hostname is specified as cisco-sj. The show host command is used to verify this information. 

    Device# configure terminal
Device(config)# ipv6 host cisco-sj 2001:DB8:20:1::12
Device(config)# end
Device# show host
Default domain is not set
Name/address lookup uses static mappings
Codes:UN - unknown, EX - expired, OK - OK, ?? - revalidate
       temp - temporary, perm - permanent
       NA - Not Applicable None - Not defined
Host                 Port  Flags      Age Type   Address(es)
cisco-sj             None  (perm, OK)  0  IPv6 2001:DB8:20:1::12

    To enable Telnet access to a device, create a vty interface and password: 

    Device(config)# line vty 0 4
password lab
login

    To use Telnet to access the device, you must enter the password: 

    Device# telnet cisco-sj
Trying cisco-sj (2001:DB8:20:1::12)... Open
User Access Verification
Password:
cisco-sj
.
.
.
verification

    It is not necessary to use the telnet command. Specifying either the hostname or the address is sufficient, as shown in the following examples: 

    Device# cisco-sj

    or 

    Device# 2001:DB8:20:1::12

    To display the IPv6 connected user (line 130) on the device to which you are connected, use the show users command: 

    Device# show users
    Line       User       Host(s)              Idle       Location
*  0 con 0                idle                 00:00:00
 130 vty 0                idle                 00:00:22   8800::3

    Note that the address displayed is the IPv6 address of the source of the connection. If the hostname of the source is known (either through a domain name server [DNS] or locally in the host cache), then it is displayed instead: 

    Device# show users
    Line       User       Host(s)              Idle       Location
*  0 con 0                idle                 00:00:00
 130 vty 0                idle                 00:02:47   cisco-sj

    If the user at the connecting device suspends the session with ^6x and then enters the show sessions command, the IPv6 connection is displayed: 

    Device# show sessions
Conn Host                Address              Byte  Idle Conn Name
*  1 cisco-sj 2001:DB8:20:1::12      0     0 cisco-sj

    The Conn Name field shows the hostname of the destination only if it is known. If it is not known, the output might look similar to the following: 

    Device# show sessions
Conn Host                Address              Byte  Idle Conn Name
*  1 2001:DB8:20:1::12 2001:DB8:20:1::12      0     0 2001:DB8:20:1::12

    Additional References for IPv6 Source Guard and Prefix Guard

    Related Documents

    Related Topic

    Document Title

    IPv6 addressing and connectivity

    IPv6 Configuration Guide

    IPv4 addressing

    IP Addressing: IPv4 Addressing Configuration Guide

    Cisco IOS commands

    Cisco IOS Master Command List, All Releases

    IPv6 commands

    Cisco IOS IPv6 Command Reference

    Cisco IOS IPv6 features

    Cisco IOS IPv6 Feature Mapping

    Standards and RFCs

    Standard/RFC

    Title

    RFCs for IPv6

    IPv6 RFCs

    Technical Assistance

    Description

    Link

    The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

    http:/​/​www.cisco.com/​cisco/​web/​support/​index.html

    Feature Information for Telnet Access over IPv6

    The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

    Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

    Table 1 Feature Information for Telnet Access over IPv6

    Feature Name

    Releases

    Feature Information

    Telnet Access over IPv6

    12.2(2)T

    12.2(18)SXE

    12.2(25)SEA

    12.2(25)SG

    12.2(33)SRA

    15.0(2)SG

    Cisco IOS XE Release 2.1

    Cisco IOS XE Release 3.2SG

    Telnet access over IPv6 is supported.

    The following commands were introduced or modified: ipv6 access-class, ipv6 host.