Remote Access

SSH vs Telnet

SSH and Telnet are both protocols for remote access, but there are differences between the two:

Security: SSH provides encrypted communication, while Telnet is insecure and sends data in clear text.

Port numbers: SSH uses port 22, Telnet uses port 23.

Functionality: SSH provides secure terminal emulation and also supports file transfers, while Telnet only provides terminal emulation.

Authentication: SSH uses public key and password-based authentication, Telnet only uses password-based authentication.

In general, SSH is preferred over Telnet for remote access due to its security and additional functionality

*Note for remote access to a router and an external device a default gateway must be configured

SSH Configuration in Cisco Packet Tracer

Topology

Router>enable

Router#configure terminal

Router(config)#interface gigabitEthernet 0/0/0

Router(config-if)#ip address 172.16.0.1 255.255.0.0  IP address of the router interface

Router(config-if)#no shutdown

Router(config-if)#exit

Router(config)#hostname FOC1 changed the name of the router

FOC1(config)#ip domain name FOC added a domain name

FOC1(config)#crypto key generate rsa   generate an ssh key using rsa

The name for the keys will be: FOC1.FOC

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  higher the number the more secure but longer to decrypt

% Generating 1024 bit RSA keys, keys will be non-exportable...[OK]

FOC1(config)#enable password friend

*Mar 1 0:4:18.119: %SSH-5-ENABLED: SSH 1.99 has been enabled

FOC1(config)#username FOC password friends adding username and password

FOC1(config)#ip ssh version 2 ssh version 

FOC1(config)#line vty 0 15  16 possible connections

FOC1(config-line)#transport input ssh type of connection ssh

FOC1(config-line)#login local local login