- The algorithm is selected using the -t option and key size using the -b option. The following commands illustrate: ssh-keygen -t rsa -b 4096 ssh-keygen -t dsa ssh-keygen -t ecdsa -b 521 ssh-keygen -t ed25519 Specifying the File Name. Normally, the tool prompts for the file in which to store the key.
- Router(config)# crypto key generate rsa general-keys The name for the keys will be: myrouter.example.com Choose the size of the key modulus in the range of 360 to 2048 for your General Purpose Keys. Choosing a key modulus greater than 512 may take a few minutes.
With a secure shell (SSH) key pair, you can create virtual machines (VMs) in Azure that use SSH keys for authentication, eliminating the need for passwords to sign in. This article shows you how to quickly generate and use an SSH public-private key file pair for Linux VMs. You can complete these steps with the Azure Cloud Shell, a macOS or Linux host, the Windows Subsystem for Linux, and other tools that support OpenSSH.
Note
VMs created using SSH keys are by default configured with passwords disabled, which greatly increases the difficulty of brute-force guessing attacks.
For more background and examples, see Detailed steps to create SSH key pairs.
For additional ways to generate and use SSH keys on a Windows computer, see How to use SSH keys with Windows on Azure.
License State: Active, Not in Use, EULA not accepted License Count: Non-Counted Switch# show license in-use returns nothing. If it set: Switch(config)# license boot level entservices. Then entservices is activated but as Evaluation. After a couple of reboot and tests I didn't manage to get the permanent entservices.
Supported SSH key formats
Azure currently supports SSH protocol 2 (SSH-2) RSA public-private key pairs with a minimum length of 2048 bits. Other key formats such as ED25519 and ECDSA are not supported.
Create an SSH key pair
When you log in to the server from the client computer, you are prompted for a passphrase for the key instead of a user password. If the installed ssh uses the AES-128-CBC cipher, RXA cannot fetch the private key from the file. RSA key-based authentication does not work. To support RSA key-based authentication, take one of the following actions. We have two cisco catalyst 4500 L3 switch (cat4500e) and running version 15.2(2)E5a. We are not able to configure ssh on this switch, ssh commands not supported and transport input ssh command also not working. Any way is there for ssh on 4500e and why command is not working.
Use the
ssh-keygen
command to generate SSH public and private key files. By default, these files are created in the ~/.ssh directory. You can specify a different location, and an optional password (passphrase) to access the private key file. If an SSH key pair with the same name exists in the given location, those files are overwritten.The following command creates an SSH key pair using RSA encryption and a bit length of 4096:
If you use the Azure CLI to create your VM with the az vm create command, you can optionally generate SSH public and private key files using the
--generate-ssh-keys
option. The key files are stored in the ~/.ssh directory unless specified otherwise with the --ssh-dest-key-path
option. The --generate-ssh-keys
option will not overwrite existing key files, instead returning an error. In the following command, replace VMname and RGname with your own values:Provide an SSH public key when deploying a VM
To create a Linux VM that uses SSH keys for authentication, specify your SSH public key when creating the VM using the Azure portal, Azure CLI, Azure Resource Manager templates, or other methods:
If you're not familiar with the format of an SSH public key, you can display your public key with the following
cat
command, replacing ~/.ssh/id_rsa.pub
with the path and filename of your own public key file if needed:![Using rsa keys generated from 4500 switch free Using rsa keys generated from 4500 switch free](/uploads/1/2/6/1/126169176/798234747.png)
A typical public key value looks like this example:
If you copy and paste the contents of the public key file to use in the Azure portal or a Resource Manager template, make sure you don't copy any trailing whitespace. To copy a public key in macOS, you can pipe the public key file to
pbcopy
. Similarly in Linux, you can pipe the public key file to programs such as xclip
.The public key that you place on your Linux VM in Azure is by default stored in ~/.ssh/id_rsa.pub, unless you specified a different location when you created the key pair. To use the Azure CLI 2.0 to create your VM with an existing public key, specify the value and optionally the location of this public key using the az vm create command with the
--ssh-key-values
option. In the following command, replace VMname, RGname, and keyFile with your own values:If you want to use multiple SSH keys with your VM, you can enter them in a space-separated list, like this
--ssh-key-values sshkey-desktop.pub sshkey-laptop.pub
.SSH into your VM
With the public key deployed on your Azure VM, and the private key on your local system, SSH into your VM using the IP address or DNS name of your VM. In the following command, replace azureuser and myvm.westus.cloudapp.azure.com with the administrator user name and the fully qualified domain name (or IP address):
If you specified a passphrase when you created your key pair, enter that passphrase when prompted during the login process. The VM is added to your ~/.ssh/known_hosts file, and you won't be asked to connect again until either the public key on your Azure VM changes or the server name is removed from ~/.ssh/known_hosts.
If the VM is using the just-in-time access policy, you need to request access before you can connect to the VM. For more information about the just-in-time policy, see Manage virtual machine access using the just in time policy.
Next steps
- For more information on working with SSH key pairs, see Detailed steps to create and manage SSH key pairs.
- If you have difficulties with SSH connections to Azure VMs, see Troubleshoot SSH connections to an Azure Linux VM.
Q: I have a Cisco switch in my network, which I can access by hooking up a console cable directly to the device. I like to access the switch remotely using SSH. How can I enable ssh on my Cisco 3750 Catalyst Switch?
A: By default, when you configure a Cisco device, you have to use the console cable and connect directly to the system to access it. Follow the steps mentioned below, which will enable SSH access to your Cisco devices. Once you enable SSH, you can access it remotely using PuTTY or any other SSH client.
A: By default, when you configure a Cisco device, you have to use the console cable and connect directly to the system to access it. Follow the steps mentioned below, which will enable SSH access to your Cisco devices. Once you enable SSH, you can access it remotely using PuTTY or any other SSH client.
1. Setup Management IP
First, make sure you have performed basic network configurations on your switch. For example, assign default gateway, assign management ip-address, etc. If this is already done, skip to the next step.
In the following example, the management ip address is set as 192.168.101.2 in the 101 VLAN. The default gateway points to the firewall, which is 192.168.101.1
2. Set hostname and domain-name
Next, make sure the switch has a hostname and domain-name set properly.
3. Generate the RSA Keys
Using Rsa Keys Generated From 4500 Switch Number
The switch or router should have RSA keys that it will use during the SSH process. So, generate these using crypto command as shown below.
Also, if you are running on an older Cisco IOS image, it is highly recommended that you upgrade to latest Cisco IOS.
4. Setup the Line VTY configurations
Setup the following line vty configuration parameters, where input transport is set to SSH. Set the login to local, and password to 7.
If you have not set the console line yet, set it to the following values.
5. Create the username password
If you don’t have an username created already, do it as shown below.
Note: If you don’t have the enable password setup properly, do it now.
Make sure the password-encryption service is turned-on, which will encrypt the password, and when you do “sh run”, you’ll seee only the encrypted password and not clear-text password.
5. Verify SSH access
From the switch, if you do ‘sh ip ssh’, it will confirm that the SSH is enabled on this cisco device.
After the above configurations, login from a remote machine to verify that you can ssh to this cisco switch.
In this example, 192.168.101.2 is the management ip-address of the switch.
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