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1. Generate Rsa Key Cisco Switch
2. Create Rsa Key Cisco Router
3. Create Rsa Keys Cisco
4. Generate Rsa Key Cisco 3750 Password

Contents

Hi When i'm trying to SSH to my 3750 switch i get the following error: Unable to negotiate with 192.168.1.250 port 22: no matching key exchange method found. Their offer: diffie-hellman-group1-sha1 I tried to use the command ip ssh dh min size 4096, but my switch doesn't know it. Here is the confi. Switch (config)# crypto key generate rsa Enables the SSH server for local and remote authentication on the switch and generates an RSA key pair. Generating an RSA key pair for the switch automatically enables SSH. We recommend that a minimum modulus size of 1024 bits. When you generate RSA keys, you are prompted to enter a modulus length. Jul 22, 2015  Authenticating to Cisco devices using SSH and your RSA Public Key Using an RSA Public/Private key pair instead of a password to authenticate an SSH session is popular on Linux/Unix boxes. Digital Ocean, a Virtual Private Server (VPS) provider, has this advice on how you should log into their Droplets: 'you should use public key authentication. Would you like to learn how to enable Cisco SSH remote access using the command-line? In this tutorial, we are going to show you all the steps required to configure the SSH remote access on a Cisco Switch 2960 or 3750 using the command-line.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release.

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

Prerequisites for Configuring the Switch for Secure Shell (SSH) and Secure Copy Protocol (SCP)

The following are the prerequisites for configuring the switch for secure shell (SSH):

• For SSH to work, the switch needs an RSA public/private key pair. This is the same with Secure Copy Protocol (SCP), which relies on SSH for its secure transport.
• Before enabling SCP, you must correctly configure SSH, authentication, and authorization on the switch.
• Because SCP relies on SSH for its secure transport, the router must have an Rivest, Shamir, and Adelman (RSA) key pair.
• SCP relies on SSH for security.
• SCP requires that authentication, authorization, and accounting (AAA) authorization be configured so the router can determine whether the user has the correct privilege level.
• A user must have appropriate authorization to use SCP.
• A user who has appropriate authorization can use SCP to copy any file in the Cisco IOS File System (IFS) to and from a switch by using the copy command. An authorized administrator can also do this from a workstation.

Restrictions for Configuring the Switch for SSH

The following are restrictions for configuring the switch for secure shell.

• The switch supports Rivest, Shamir, and Adelman (RSA) authentication.
• SSH supports only the execution-shell application.
• The SSH server and the SSH client are supported only on DES (56-bit) and 3DES (168-bit) data encryption software.
• The switch supports the Advanced Encryption Standard (AES) encryption algorithm with a 128-bit key, 192-bit key, or 256-bit key. However, symmetric cipher AES to encrypt the keys is not supported.
• This software release does not support IP Security (IPSec).
• When using SCP, you cannot enter the password into the copy command. You must enter the password when prompted.

Information about SSH

Secure Shell (SSH) is a protocol that provides a secure, remote connection to a device. SSH provides more security for remote connections than Telnet does by providing strong encryption when a device is authenticated. This software release supports SSH Version 1 (SSHv1) and SSH Version 2 (SSHv2).

SSH and Switch Access

For SSH configuration examples, see the “SSH Configuration Examples” section in the “Configuring Secure Shell” section in the “Other Security Features” chapter of the Cisco IOS Security Configuration Guide, Cisco IOS Release 12.4.

SSH functions the same in IPv6 as in IPv4. For IPv6, SSH supports IPv6 addresses and enables secure, encrypted connections with remote IPv6 nodes over an IPv6 transport.

SSH Servers, Integrated Clients, and Supported Versions

The SSH feature has an SSH server and an SSH integrated client, which are applications that run on the switch. You can use an SSH client to connect to a switch running the SSH server. The SSH server works with the SSH client supported in this release and with non-Cisco SSH clients. The SSH client also works with the SSH server supported in this release and with non-Cisco SSH servers.

The switch supports an SSHv1 or an SSHv2 server.

The switch supports an SSHv1 client.

SSH supports the Data Encryption Standard (DES) encryption algorithm, the Triple DES (3DES) encryption algorithm, and password-based user authentication.

SSH also supports these user authentication methods:

• TACACS+
• RADIUS
• Local authentication and authorization

SSH Configuration Guidelines

Follow these guidelines when configuring the switch as an SSH server or SSH client:

• An RSA key pair generated by a SSHv1 server can be used by an SSHv2 server, and the reverse.
• If the SSH server is running on a stack master and the stack master fails, the new stack master uses the RSA key pair generated by the previous stack master.
• If you get CLI error messages after entering the crypto key generate rsa global configuration command, an RSA key pair has not been generated. Reconfigure the hostname and domain, and then enter the crypto key generate rsa command. For more information, see Related Topics below.
• When generating the RSA key pair, the message No host name specified might appear. If it does, you must configure a hostname by using the hostname global configuration command.
• When generating the RSA key pair, the message No domain specified might appear. If it does, you must configure an IP domain name by using the ip domain-name global configuration command.
• When configuring the local authentication and authorization authentication method, make sure that AAA is disabled on the console.

Secure Copy Protocol Overview

The Secure Copy Protocol (SCP) feature provides a secure and authenticated method for copying switch configurations or switch image files. SCP relies on Secure Shell (SSH), an application and a protocol that provides a secure replacement for the Berkeley r-tools.

For SSH to work, the switch needs an RSA public/private key pair. This is the same with SCP, which relies on SSH for its secure transport.

Because SSH also relies on AAA authentication, and SCP relies further on AAA authorization, correct configuration is necessary.

• Before enabling SCP, you must correctly configure SSH, authentication, and authorization on the switch.
• Because SCP relies on SSH for its secure transport, the router must have an Rivest, Shamir, and Adelman (RSA) key pair.

Secure Copy Protocol Concepts

The Secure Copy Protocol (SCP) feature provides a secure and authenticated method for copying switch configurations or switch image files. SCP relies on Secure Shell (SSH), an application and a protocol that provides a secure replacement for the Berkeley r-tools.

To configure the Secure Copy feature, you should understand the SCP concepts.

The behavior of SCP is similar to that of remote copy (rcp), which comes from the Berkeley r-tools suite, except that SCP relies on SSH for security. SCP also requires that authentication, authorization, and accounting (AAA) authorization be configured so the router can determine whether the user has the correct privilege level.

For information about how to configure and verify SCP, see the “Secure Copy Protocol” section in the Cisco IOS Security Configuration Guide: Securing User Services, Release 12.4.

How to Configure SSH

Setting Up the Switch to Run SSH

Beginning in privileged EXEC mode, follow these steps to set up your switch to run SSH:

Configure user authentication for local or remote access. This step is required. For more information, see Related Topics below.

1.configureterminal


2.hostnamehostname


3.ip domain-namedomain_name


4.crypto key generate rsa


5.end

Configuring the SSH Server

Beginning in privileged EXEC mode, follow these steps to configure the SSH server:

1.configureterminal


2.ip sshversion [12]


3.ip ssh {timeoutsecondsauthentication-retriesnumber}


4.Use one or both of the following:

• transport input ssh

5.end

Monitoring the SSH Configuration and Status

Generate Rsa Key Cisco Switch

For more information about these commands, see the “Secure Shell Commands” section in the “Other Security Features” chapter of the Cisco IOS Security Command Reference .

Additional References

Related Documents

Error Message Decoder

MIBs

Create Rsa Key Cisco Router

Technical Assistance

Hi,

Are you aware of any inbound ACLs applied on the VTY lines? Maybe do a show access-list, show ip interface and show run commands to check if an ACL is blocking access on the terminal lines.

If its not an ACL issue, make sure you configured 'login local' on your VTY lines to make use of the local database when connecting in

Create Rsa Keys Cisco

Check also that you have not disabled SSH access into your VTY lines using the transport command.

Make sure 'transport input ssh telnet' or 'transport input telnet ssh' has been configured

Generate Rsa Key Cisco 3750 Password

Failing all that it could be an exec-timeout issue, maybe that has been set to low and its automatically logging you out, although this is more unlikely based on your report.