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. Solved: I read from the manual that the key pair will be used for SSH but just wonder does the command 'crypto key generate rsa' is necessary to enable SSH on ASA? I can access to my firewall via SSH but when I checked in the configuration on ASA.
I’ve lost count of the number of times this has happened to me! Most of my colleagues prefer to use the ASDM for remote management, but if (like me) you work at command line, then sometimes people <ahem> forget to generate the RSA keypair when deploying a firewall. Then even if SSH access and AAA is setup correctly, you still can’t get in via SSH. Instead you see the following;
RoyalTS and RoyalTSX: ssh_exchange_identification: Connection closed by remote host.
PuTTY: PuTTY Fatal Error: Server unexpectedly closed network connection.
SecureCRT: Connection closed.
OSX/Linux: ssh_exchange_identification: Connection closed by remote host.
Now at command line you can fix this with a ‘Crypto Key Generate RSA Modulus 2048‘ command, but you can’t get to command line only ASDM.
Solution
On older versions of the ASDM you could generate the keypair in the Identification Certificates section (well you still can but only if you are also generating a certificate request file). So, as we are command line warriors, lets use the ASDM’s command line!
Tools > Command Line Interface > Multiple Line
Send > Wait a couple of minutes and try again.
REMEMBER: I’m assuming you have SSH setup correctly if not, see the following article;
Related Articles, References, Credits, or External Links
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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:
Crate a Packet Tracer Topology Lab
Basic IP Setting for connectivity
Set hostname and domain-name on Switch
Set console and enable password for SSH login
Generate the RSA Keys
Setup the Line VTY configurations
Create the username password for SSH access from PC
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 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
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
Cisco Switch Can't Generate Crypto Key Rsa
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..!
