• May 20, 2014 Author, teacher, and talk show host Robert McMillen shows you how to use the Cisco ASA version 9 generate RSA keys command.
• Jun 28, 2007  If your SSH configuration commands are rejected as illegal commands, you have not successfully generated a RSA key pair for your router. Make sure you have specified a host name and domain. Then use the crypto key generate rsa command to generate an RSA key pair and enable the SSH.

• Switch Crypto Key Generate Rsa Login
• Switch Crypto Key Generate Rsa Modulus 1024

Configuration of SSH on Cisco Switch in Packet Tracer 2019

Run show crypto key mypubkey rsa to see if you do, in fact, have a key fully generated and registered under a non-default name. If there is, then you can tell the ssh process to use this key with ip ssh rsa keypair-name xxx.If the first command doesn't show anything useful then I'd say you can go ahead and generate a new key. Show crypto key mypubkey rsa: Shows information about the SSL certificate If you’d like to learn more about on how to configure SSH on a Cisco router I recommend you read through this documentation: Configuring Secure Shell on Routers and Switches Running Cisco IOS. Configuring Secure Shell (SSH) Steps for Configuring and Using SSH for Switch and Client Authentication B. Switch Preparation 1. Assign a login (Operator) and enable (Manager) password on the switch (page 6-9). Generate a public/private key pair on the switch (page 6-10). You need to do this only once. The key remains in the switch even if. Crypto key generate rsa label label-string exportable modulus size Example: switch(config)# crypto key generate rsa exportable. Generates an RSA key pair. The maximum number of key pairs on a device is 16. The label string is alphanumeric, case sensitive, and has a maximum length of 64 characters.

This Article is about the configuration of SSH on Cisco Switch. You can configure SSH on Cisco devices very easily using these simple steps:

1. Crate a Packet Tracer Topology Lab
2. Basic IP Setting for connectivity
3. Set hostname and domain-name on Switch
4. Set console and enable password for SSH login
5. Generate the RSA Keys
6. Setup the Line VTY configurations
7. Create the username password for SSH access from PC
8. Verify SSH access

For the configurations of SSH in packet tracer on Cisco switch, you are required to follow the above steps. Let start and perform these steps one by one. (Learn what is PSSH)

Crate a Packet Tracer Topology Lab

Our first step is to open the packet tracer and need to create a simple lab. For this topology we will use only one switch and a PC. Simply drag these two items on dashboard. Now we will connect them with straight through connection.

Basic IP Setting for connectivity

The next step is assign the suitable IP setting to these devices. For keeping it simple and making basic connectivity we will assign just two IP address to these device. We will assign the IP address to PC. For this will open the PC setting and then IP configuration. Here we will assign an IP address to host, in our case we are going to assign it 192.168.1.1 with the default gateway. For default gateway we will assign the IP address 192.168.1.10. We assign the second IP address to our Vlan1 interface on switch. And its IP address will be the gateway of host that is 192.168.1.10. For this we will use the basic commands.
Switch> enable

Switch# config t

Switch(config)#interface vlan 1

Switch (config-if)# ip address 192.168.1.10 255.255.255.0

Switch (config -if)#no shut

Once you done with basic IP setting, you can verify the connectivity by pinging the interface vlan1 IP from host.

Set host-name and domain-name on Switch

For SSh configurations you need to configure a host-name and domain-name for your switch you can do this with these simple commands.

Switch # config t

Switch (config)#hostname SW1

SW1 ( config)#ip domain-name w7cloud.com

Set console and enable password for SSH login

For SSH access it is required that you must configure the console and enable password on your cisco switch. You can set these two passwords with following commands.

SW1 ( config)#line console 0Download fifa 17 key generator for pc.

SW1(config-line)#password cisco

SW1(config -line)#logging synchronous

SW1(config- line)#login local

SW1 (config- line)#exit

SW1 # enable secret cisco

Generate the RSA Keys

Your Cisco switch must have RSA keys that for the SSH process. You can generate the RSA keys with following command:

SW1 ( config)# crypto key generate rsa

How many bits in the modulus [512]: 1024

% Generating 1024 bit RSA keys, keys will be non-exportable…[OK]

Set the size of key to 1024 bits.

If your Cisco Switch is running an older version of Cisco IOS image, then it is extremely recommended that you upgrade to latest Cisco IOS.

Setup the Line VTY configurations

For the configuration of SSH on cisco switch you need the following line vty configurations, and input transport is required to set to SSH. Set the login-to-local, & password to 7.

sw1 ( config)#line vty 0 4

sw1 ( config-line)#transport input ssh

sw1( config -line)#login local

sw1(config- line)#password 7

sw1(config- line ) #exit

Create the username password for SSH access from PC

If you do not have a username for SSH access you need to create a username. You can do it with this simple command:

Sw1# config t

sw1 (config ) # username w7cloud password cisco

Make sure the password encryption services is enabled on your switch, this service will encrypt your password, & when you do “sh run”, you’ll see only the encrypted password, not clear text password.

SW1# service password-encryption

Verify SSH access from Host

Once you done with the above configurations you can test all these configuration by creating a SSH connection from Host. You do it the command ssh –l <username> <IP address>. Open the host command prompt and use the command

C:>ssh -l waqas 192.168.1.10

It will ask for password, provide the password that you created with this username in previous steps. Then it asked for console password and then you need to provide the enable password. Now you are in your Cisco switch. You can perform switch configurations from your host.

From the switch, if you use the command ‘sh ip ssh’, it will also confirm that SSH is enabled on this cisco swith.

For better understanding please watch the video and like it.

I hope this will be a helpful for you, please share your comments. If you like this then share this on social media. Thank you for reading this.!

Guide on Cisco Router Configuration for Beginners

Related: 4 Best SSH Client Used by Professionals

Contents

Introduction

Secure Shell (SSH) is a protocol which provides a secure remote access connection to network devices. Communication between the client and server is encrypted in both SSH version 1 and SSH version 2. Implement SSH version 2 when possible because it uses a more enhanced security encryption algorithm.

This document discusses how to configure and debug SSH on Cisco routers or switches that run a version of Cisco IOS^® Software that supports SSH. This document contains more information on specific versions and software images.

Prerequisites

Requirements

The Cisco IOS image used must be a k9(crypto) image in order to support SSH. For example c3750e-universalk9-tar.122-35.SE5.tar is a k9 (crypto) image.

Components Used

The information in this document is based on Cisco IOS 3600 Software (C3640-IK9S-M), Release 12.2(2)T1.

SSH was introduced into these Cisco IOS platforms and images:

• SSH Version 1.0 (SSH v1) server was introduced in some Cisco IOS platforms and images that start in Cisco IOS Software Release 12.0.5.S.

• SSH client was introduced in some Cisco IOS platforms and images starting in Cisco IOS Software Release 12.1.3.T.

• SSH terminal-line access (also known as reverse-Telnet) was introduced in some Cisco IOS platforms and images starting in Cisco IOS Software Release 12.2.2.T.

• SSH Version 2.0 (SSH v2) support was introduced in some Cisco IOS platforms and images starting in Cisco IOS Software Release 12.1(19)E.

• Refer to How to Configure SSH on Catalyst Switches Running CatOS for more information on SSH support in the switches.

Refer to the Software Advisor (registered customers only) for a complete list of feature sets supported in different Cisco IOS Software releases and on different platforms.

The information presented in this document was created from devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If you are in a live network, make sure that you understand the potential impact of any command before you use it.

Conventions

Refer to Cisco Technical Tips Conventions for more information on document conventions.

Switch Crypto Key Generate Rsa Login

SSH v1 vs. SSH v2

Use the Cisco Software Advisor (registered customers only) in order to help you find the version of code with appropriate support for either SSH v1 or SSH v2.

Network Diagram

Test Authentication

Authentication Test without SSH

First test the authentication without SSH to make sure that authentication works with the router Carter before you add SSH. Authentication can be with a local username and password or with an authentication, authorization, and accounting (AAA) server that runs TACACS+ or RADIUS. (Authentication through the line password is not possible with SSH.) This example shows local authentication, which lets you Telnet into the router with username 'cisco' and password 'cisco.'

Authentication Test with SSH

In order to test authentication with SSH, you have to add to the previous statements in order to enable SSH on Carter and test SSH from the PC and UNIX stations.

At this point, the show crypto key mypubkey rsa command must show the generated key. After you add the SSH configuration, test your ability to access the router from the PC and UNIX station. If this does not work, see the debug section of this document.

Optional Configuration Settings

Prevent Non-SSH Connections

If you want to prevent non-SSH connections, add the transport input ssh command under the lines to limit the router to SSH connections only. Straight (non-SSH) Telnets are refused.

Test to make sure that non-SSH users cannot Telnet to the router Carter.

Set Up an IOS Router or Switch as SSH Client

There are four steps required to enable SSH support on a Cisco IOS router:

1. Configure the hostname command.

2. Configure the DNS domain.

3. Generate the SSH key to be used.

4. Enable SSH transport support for the virtual type terminal (vtys).

If you want to have one device act as an SSH client to the other, you can add SSH to a second device called Reed. These devices are then in a client-server arrangement, where Carter acts as the server, and Reed acts as the client. The Cisco IOS SSH client configuration on Reed is the same as required for the SSH server configuration on Carter.

Issue this command to SSH from the Cisco IOS SSH client (Reed) to the Cisco IOS SSH server (Carter) in order to test this:

• SSH v1:

• SSH v2:

Setup an IOS Router as an SSH server that performs RSA based User Authentication

Complete these steps in order to configure the SSH server to perform RSA based authentication.

1. Specify the Host name.

2. Define a default domain name.

3. Generate RSA key pairs.

4. Configure SSH-RSA keys for user and server authentication.

5. Configure the SSH username.

6. Specify the RSA public key of the remote peer.

7. Specify the SSH key type and version. (optional)

8. Exit the current mode and return to privileged EXEC mode.

   Note: Refer to Secure Shell Version 2 Support for more information.

Add SSH Terminal-Line Access

If you need outbound SSH terminal-line authentication, you can configure and test SSH for outbound reverse Telnets through Carter, which acts as a comm server to Philly.

If Philly is attached to Carter's port 2, then you can configure SSH to Philly through Carter from Reed with the help of this command:

• SSH v1:

• SSH v2:

You can use this command from Solaris:

Restrict SSH access to a subnet

You need to limit SSH connectivity to a specific subnetwork where all other SSH attempts from IPs outside the subnetwork should be dropped.

You can use these steps to accomplish the same:

1. Gnupg generate rsa key pair. Define an access-list that permits the traffic from that specific subnetwork.

2. Restrict access to the VTY line interface with an access-class.

Switch Crypto Key Generate Rsa Modulus 1024

This is an example configuration. In this example only SSH access to the 10.10.10.0 255.255.255.0 subnet is permitted, any other is denied access.

Note: The same procedure to lock down the SSH access is also applicable on switch platforms.

Configure the SSH Version

Configure SSH v1:

Configure SSH v2:

Configure SSH v1 and v2:

Note: You receive this error message when you use SSHv1: mac cleanup pro free download

Note: Cisco bug ID CSCsu51740 (registered customers only) is filed for this issue. Workaround is to configure SSHv2.

Variations on banner Command Output

The banner command output varies between the Telnet and different versions of SSH connections. This table illustrates how different banner command options work with various types of connections.

Unable to Display the Login Banner

SSH version 2 supports the login banner. The login banner is displayed if the SSH client sends the username when it initiates the SSH session with the Cisco router. For example, when the Secure Shell ssh client is used, the login banner is displayed. When the PuTTY ssh client is used, the login banner is not displayed. This is because Secure Shell sends the username by default and PuTTY does not send the username by default.

The Secure Shell client needs the username to initiate the connection to the SSH enabled device. The Connect button is not enabled if you do not enter the host name and username. This screenshot shows that the login banner is displayed when Secure Shell connects to the router. Then, the login banner password prompt displays.

The PuTTY client does not require the username to initiate the SSH connection to the router. This screenshot shows that the PuTTY client connects to the router and prompts for the username and password. It does not display the login banner.

This screen shot shows that the login banner is displayed when PuTTY is configured to send the username to the router.

debug and show Commands

Before you issue the debug commands described and illustrated here, refer to Important Information on Debug Commands. Certain show commands are supported by the Output Interpreter Tool (registered customers only) , which allows you to view an analysis of show command output.

• debug ip ssh—Displays debug messages for SSH.

• show ssh—Displays the status of SSH server connections.

• show ip ssh—Displays the version and configuration data for SSH.

  • Version 1 Connection and no Version 2

  • Version 2 Connection and no Version 1

  • Version 1 and Version 2 Connections

Sample Debug Output

Router Debug

Note: Some of this good debug output is wrapped to multiple lines because of spatial considerations.

Server Debug

Note: This output was captured on a Solaris machine.

What can go Wrong

These sections have sample debug output from several incorrect configurations.

SSH From an SSH Client Not Compiled with Data Encryption Standard (DES)

Solaris Debug

Router Debug

Bad Password

Router Debug

SSH Client Sends Unsupported (Blowfish) Cipher

Router Debug

Geting the '%SSH-3-PRIVATEKEY: Unable to retrieve RSA private key for' Error

If you receive this error message, it may be caused due to any change in the domain name or host name. In order to resolve this, try these workarounds.

• Zeroize the RSA keys and re-generate the keys.

• If the previous workaround does not work, try these steps:

  1. Zeroize all RSA keys.

  2. Reload the device.

  3. Create new labeled keys for SSH.

Cisco bug ID CSCsa83601 (registered customers only) has been filed to address this behaviour.

Troubleshooting Tips

• If your SSH configuration commands are rejected as illegal commands, you have not successfully generated a RSA key pair for your router. Make sure you have specified a host name and domain. Then use the crypto key generate rsa command to generate an RSA key pair and enable the SSH server.

• When you configure the RSA key pair, you might encounter these error messages:

  1. No hostname specified

     You must configure a host name for the router using the hostname global configuration command.

  2. No domain specified

     You must configure a host domain for the router using the ip domain-name global configuration command.

• The number of allowable SSH connections is limited to the maximum number of vtys configured for the router. Each SSH connection uses a vty resource.

• SSH uses either local security or the security protocol that is configured through AAA on your router for user authentication. When you configure AAA, you must ensure that the console is not running under AAA by applying a keyword in the global configuration mode to disable AAA on the console.

• No SSH server connections running.

  This output suggests that the SSH server is disabled or not enabled properly. If you have already configured SSH, it is recommended that you reconfigure the SSH server in the device. Complete these steps in order to reconfigure SSH server on the device.

  1. Delete the RSA key pair. After the RSA key pair is deleted, the SSH server is automatically disabled.

     Note: It is important to generate a key-pair with at least 768 as bit size when you enable SSH v2.

     Caution: This command cannot be undone after you save your configuration, and after RSA keys have been deleted, you cannot use certificates or the CA or participate in certificate exchanges with other IP Security (IPSec) peers unless you reconfigure CA interoperability by regenerating RSA keys, getting the CA's certificate, and requesting your own certificate again.Refer to crypto key zeroize rsa - Cisco IOS Security Command Reference, Release 12.3 for more information on this command.

  2. Reconfigure the hostname and domain name of the device.

  3. Generate an RSA key pair for your router, which automatically enables SSH.

     Refer to crypto key generate rsa - Cisco IOS Security Command Reference, Release 12.3 for more information on the usage of this command.

     Note: You can receive the SSH2 0: Unexpected mesg type received error message due to a packet received that is not understandable by the router. Increase the key length while you generate rsa keys for ssh in order to resolve this issue.

  4. Configure SSH server. In order to enable and configure a Cisco router/switch for SSH server, you can configure SSH parameters. If you do not configure SSH parameters, the default values are used.

     ip ssh {[timeout seconds] [authentication-retries integer]}

     Refer to ip ssh - Cisco IOS Security Command Reference, Release 12.3 for more information on the usage of this command.

Related Information