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This chapter contains the following sections:
The Telnet protocol enables you to set up TCP/IP connections to a host. Telnet allows a user at one site to establish a TCP connection to a login server at another site and then pass the keystrokes from one device to the other. Telnet can accept either an IPv4 or IPv6 address or a domain name as the remote device address.
You have configured IP on a Layer 3 interface, out of band on the mgmt 0 interface, or inband on an Ethernet interface. Telnet supports both IPv4 and IPv6 addresses.
The Telnet server is disabled by default
Cisco NX-OS commands may differ from Cisco IOS commands.
|
Parameter |
Default |
|---|---|
|
Telnet server |
Enabled |
Configuring Telnet
The Telnet server is enabled by default, but you can reenable it if necessary.
Log in to the CLI in EXEC mode.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
switch# configure terminal |
Enters global configuration mode. |
| Step 2 |
switch(config)# feature telnet |
Enables the Telnet server. |
| Step 3 |
(Optional) switch(config)# show telnet server |
(Optional)
Displays the Telnet server configuration. |
| Step 4 |
(Optional) switch(config)# copy running-config startup-config |
(Optional)
Copies the running configuration to the startup configuration. |
This example shows how to enable the Telnet server:
switch# configure terminal
switch(config)# feature telnet
switch(config)# show telnet server
telnet service enabled
switch(config)# copy running-config startup-config
Log in to the CLI in EXEC mode.
Verify that the Telnet server is enabled and that it is also enabled on the remote device.
Obtain the hostname for the remote device and, if needed, the username on the remote device.
| Command or Action | Purpose |
|---|---|
|
switch# telnet {ipv4-address | host-name} [port-number] [vrf vrf-name] |
Creates an IP Telnet session to the specified destination. The keywords and arguments are as follows:
|
Log in to the CLI in EXEC mode.
Verify that the Telnet server is enabled and that it is also enabled on the remote device.
Obtain the hostname for the remote device and, if needed, the username on the remote device.
| Command or Action | Purpose |
|---|---|
|
switch# telnet6 {ipv6-address | host-name} [port-number] [vrf vrf-name] |
Creates an IP Telnet session to the specified destination. The keywords and arguments are as follows:
|
Log in to the CLI in EXEC mode.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
switch# show users |
Displays user session information. |
| Step 2 |
switch# clear line vty-line |
Clears a user Telnet session. |
| Step 3 |
(Optional) switch# show users |
(Optional)
Displays user session information. |
This example shows how to clear a Telnet session:
switch# show users
NAME LINE TIME IDLE PID COMMENT
admin tty1 Jul 25 19:13 old 2867
admin pts/1 Jul 28 14:04 . 31453 (::ffff:171.70.209.8)
admin pts/2 Jul 28 14:04 . 31475 (171.70.209.8)*
switch# clear line 1
switch# show users
NAME LINE TIME IDLE PID COMMENT
admin tty1 Jul 25 19:13 old 2867
admin pts/2 Jul 28 14:04 . 31475 (171.70.209.8)*
switch#
Use the following commands to verify the configuration.
|
Command |
Purpose |
|---|---|
|
show running-config security [all ] |
Displays the user account configuration in the running configuration. The all keyword displays the default values for the user accounts. |
|
show telnet server |
Displays the telnet server configuration. |
|
show hosts |
Displays the configuration details for current hosts. |
|
show tcp connection |
Displays connection information. |
This table only includes updates for those releases that have resulted in additions to the feature.
|
Feature Name |
Feature Information |
|
|---|---|---|
|
IPv6 support |
5.2(1)SV3(1.1) |
IPv6 support was added. |
|
Telnet |
4.0(4)SV1(1) |
This feature was introduced. |
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