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How to Enable SSH on Cisco Switch, Router and ASA

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.

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 in the 101 VLAN. The default gateway points to the firewall, which is

# ip default-gateway

# interface vlan 101
(config-if)# ip address

2. Set hostname and domain-name

Next, make sure the switch has a hostname and domain-name set properly.

# config t
(config)# hostname myswitch
(config)# ip domain-name thegeekstuff.com

3. Generate the RSA Keys

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.

myswitch(config)# crypto key generate rsa
 The name for the keys will be: myswitch.thegeekstuff.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.

How many bits in the modulus [512]: 1024
 % Generating 1024 bit RSA keys, keys will be non-exportable...[OK]

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.

# line vty 0 4
(config-line)# transport input ssh
(config-line)# login local
(config-line)# password 7
(config-line)# exit

If you have not set the console line yet, set it to the following values.

# line console 0
(config-line)# logging synchronous
(config-line)# login local

5. Create the username password

If you don’t have an username created already, do it as shown below.

myswitch# config t
Enter configuration commands, one per line.  End with CNTL/Z.
myswitch(config)# username ramesh password mypassword

Note: If you don’t have the enable password setup properly, do it now.

myswitch# enable secret myenablepassword

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.

myswitch# service password-encryption

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.

myswitch# sh ip ssh
SSH Enabled - version 1.99
Authentication timeout: 120 secs; Authentication retries: 3

After the above configurations, login from a remote machine to verify that you can ssh to this cisco switch.

In this example, is the management ip-address of the switch.

remote-machine# ssh
login as: ramesh
Using keyboard-interactive authentication.


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{ 15 comments… add one }

  • John August 22, 2013, 12:29 pm

    I’m using telnet to connect to my Cisco switch. Is telnet enabled by default? If yes, how should I disable that?

  • Kane August 23, 2013, 5:54 am

    To disable telnet:

    myswitch#configure terminal
    myswitch(config)#line VTY 0 15
    myswitch(config-line)#Transport preferred ssh

    This will allow only SSH connections to the device. Be sure to complete the above listed steps as well.

  • Selvam August 23, 2013, 7:12 am

    Very nice explanation! Thanks.

  • Biswajit August 23, 2013, 8:34 am

    Great post. Thanks !!!

  • Jalal Hajigholamali August 24, 2013, 9:48 pm

    Very nice and useful material…

  • Anon August 26, 2013, 1:14 am

    This is definitely not the way you do it on a Cisco ASA btw 😉

  • Pedram August 30, 2013, 3:49 am

    Anon, this is just my words coming out of your mouth 😉

  • Kane August 30, 2013, 11:38 am

    Hey Anon & Pedram,

    Why don’t you 2 enlighten us then.


  • ali January 16, 2014, 5:22 am

    very user full post, thanks for sharing it. BDY if you can also describe how to use telnet and ssh on line vty same it i will be gr8

  • prat March 28, 2014, 6:28 am

    very good explanation thanks!! a lot

  • Lossless October 16, 2014, 10:17 am

    Example ASA

    username sshuser password sshpassword
    crypto key generate rsa modulus 2048
    ssh inside
    ssh timeout 5
    ssh version 2
    aaa authentication ssh console LOCAL

  • John November 2, 2014, 12:05 am

    Hi is the RSA key ” myswitch.thegeekstuff.com” automatically chosen by the router when you key in the crypto command?

  • Mansoor Ali March 13, 2015, 11:17 am

    @JOHN:- you can choose by yourself…
    hi my question is that after enabling the SSH on a cisco device, how to Disable SSH?

  • Mansoor Ali March 13, 2015, 11:27 am

    friends i have found way to disable SSH from cisco device generally we use no before any command to remove that perticular command,
    Do notice if you use the command “no crypto key generate rsa” it will not work
    rather the device will suggest you to use the
    ‘crypto key zeroize rsa’ command, amazing…..!!!!!!!!!!

  • Harry February 15, 2016, 11:38 am

    How do you see what modulus the switch is configured for after it has been configured?

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