Generate Ssh Rsa Key Cisco

Posted on by
  • October 2, 2015
  • Posted by: Syed Shujaat
  • Category: Cisco, Networking Solutions

Use this command to generate RSA key pairs for your Cisco device (such as a router). keys are generated in pairs–one public RSA key and one private RSA key.

If your router already has RSA keys when you issue this command, you will be warned and prompted to replace the existing keys with new keys.

Click the Add button and you’ll get the Add SSH User window pop up. Make sure the Key Type is set to RSA and then go ahead and open your public SSH key file that you saved earlier using a program like Notepad. Copy the entire contents and paste it into the Public Key window. Sep 21, 2018  SSH on Cisco IOS XR. First of all, you should create hostname and domain name just like IOS or IOS-XE. (NOTE: Unlike regular IOS, IOS-XR doesn’t require hostname and domain-name to generate RSA key.) RP/0/0/CPU0:ios(config)#hostname IOS-XR RP/0/0/CPU0:ios(config)#domain name ios-xr.local. Creating RSA is a little bit different then regular IOS. The default settings are fine, we will generate a 2048 bit RSA keypair. Hit the generate button and you will see this: To generate a random key, PuTTY key generator uses the input of your mouse movement. Swing it around a bit until the keys are ready.

NOTE: Before issuing this command, ensure that your router has a hostname and IP domain name configured (with the hostname and ipdomain-name commands).

You will be unable to complete the cryptokeygeneratersacommand without a hostname and IP domain name. (This situation is not true when you generate only a named key pair.)

Here are the steps to Enable SSH and Crypto Key setup : 2 config must requried for SSH

1 Setup Local VTY line User ID and password

router (Config) # Line VTY 0 15

router (Config-line)# login local

router (Config-line)# Exit

!!! create local login ID/Pass

router (Config)# username [loginid] password [cisco]

router (Config)# username loginid1 password cisco1

2. router (Config)# ip domain-name example.com

router (Config)# crypto key generate rsa

how many bits in the modulus [512] :1024

router (Config)# ip ssh version2

router (Config)# CTRL Z


Note

Secure Shell (SSH) may generate an additional RSA key pair if you generate a key pair on a router having no RSA keys. The additional key pair is used only by SSH and will have a name such as {router_FQDN }.server.

For example, if a router name is “router1.cisco.com,” the key name is “router1.cisco.com.server.”

This command is not saved in the router configuration; however, the RSA keys generated by this command are saved in the private configuration in NVRAM (which is never displayed to the user or backed up to another device) the next time the configuration is written to NVRAM.

Modulus Length

When you generate RSA keys, you will be prompted to enter a modulus length. The longer the modulus, the stronger the security. However, a longer modules take longer to generate (see the table below for sample times) and takes longer to use.

The size of Key Modulus range from 360 to 2048. Choosing modulus greater than 512 will take longer time.

Router360 bits512 bits1024 bits2048 bits (maximum)
Cisco 250011 seconds20 seconds4 minutes, 38 secondsMore than 1 hour
Cisco 4700Less than 1 second1 second4 seconds50 seconds

Cisco IOS software does not support a modulus greater than 4096 bits. A length of less than 512 bits is normally not recommended. In certain situations, the shorter modulus may not function properly with IKE, so we recommend using a minimum modulus of 2048 bits.

Syntax Description : Optional Strings to embed with SSH Crypto key

general-keys(Optional) Specifies that a general-purpose key pair will be generated, which is the default.
usage-keys(Optional) Specifies that two RSA special-usage key pairs, one encryption pair and one signature pair, will be generated.
signature(Optional) Specifies that the RSA public key generated will be a signature special usage key.
encryption(Optional) Specifies that the RSA public key generated will be an encryption special usage key.
labelkey-label(Optional) Specifies the name that is used for an RSA key pair when they are being exported.If a key label is not specified, the fully qualified domain name (FQDN) of the router is used.
exportable(Optional) Specifies that the RSA key pair can be exported to another Cisco device, such as a router.
modulusmodulus-size(Optional) Specifies the IP size of the key modulus.By default, the modulus of a certification authority (CA) key is 1024 bits. The recommended modulus for a CA key is 2048 bits. The range of a CA key modulus is from 350 to 4096 bits.
Note Effective with Cisco IOS XE Release 2.4 and Cisco IOS Release 15.1(1)T, the maximum key size was expanded to 4096 bits for private key operations. The maximum for private key operations prior to these releases was 2048 bits.
storagedevicename:(Optional) Specifies the key storage location. The name of the storage device is followed by a colon (:).
redundancy(Optional) Specifies that the key should be synchronized to the standby CA.
ondevicename:(Optional) Specifies that the RSA key pair will be created on the specified device, including a Universal Serial Bus (USB) token, local disk, or NVRAM. The name of the device is followed by a colon (:).Keys created on a USB token must be 2048 bits or less.
CommandDescription
copyCopies any file from a source to a destination, use the copy command in privileged EXEC mode.
cryptokeystorageSets the default storage location for RSA key pairs.
debugcryptoengineDisplays debug messages about crypto engines.
hostnameSpecifies or modifies the hostname for the network server.
ipdomain-nameDefines a default domain name to complete unqualified hostnames (names without a dotted-decimal domain name).
showcryptokeymypubkeyrsaDisplays the RSA public keys of your router.
show crypto pki certificatesDisplays information about your PKI certificate, certification authority, and any registration authority certificates.

Configuration of SSH on Cisco Switch in Packet Tracer 2019

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)

Generate Rsa Key Cisco

Crate a Packet Tracer Topology Lab

Ssh

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 0

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

Cisco Ssh Rsa Key

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:

Generations

Sw1# config t

Generate Ssh Rsa Key Cisco Download

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

Create Rsa Ssh Key

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.!

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How To Generate Ssh Key Cisco

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