SSH should replace Telnet for management connections

Device	Interface	IP Address	Subnet Mask
S1	VLAN 1	10.10.10.2	255.255.255.0
PC1	NIC	10.10.10.10	255.255.255.0

SSH should replace Telnet for management connections. Telnet uses insecure plain text communications. SSH provides security for remote connections by providing strong encryption of all transmitted data between devices. In this activity, you will secure a remote switch with password encryption and SSH.

As we already have telnet connection, so firstly we are going to connect by telnet through PC1 to S1 for changing the switch configuration telnet to ssh access.

From PC1 command prompt telnet to S1 vlan IP:

PC>telnet 10.10.10.2

Trying 10.10.10.2 ...Open

User Access Verification

Password:

S1>enable

Password:

S1#

Configure the domain name to nrt.com:

S1#conf t

S1(config)#ip domain-name nrt.com

Secure keys are needed to encrypt the data. Generate the RSA keys using a 1024 key length:

S1(config)#crypto key generate rsa

The name for the keys will be: S1.nrt.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]

Create an SSH user and reconfigure the VTY lines for SSH-only access:

S1(config)#username administrator password sshlogin

S1(config)#service password-encryption

Configure the VTY lines to check the local username database for login credentials and to only allow SSH for remote access. Remove the existing vty line password:

S1(config)#line vty 0 15

S1(config-line)#login local

S1(config-line)#no password

S1(config-line)#transport input ssh

  Exit the Telnet session and attempt to log back in using Telnet. The attempt should fail. Attempt to log in using SSH with below command at PC1 command prompt (Password- sshlogin).

PC>ssh -l administrator 10.10.10.2

Open

Password:

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