It is also worth noting that a key of at least 768 bits must be generated to enable SSHv2. In the above output, the system is showing SSH support, but it’s currently disabled as no RSA key has been generated. IOS Keys in SECSH format(ssh-rsa, base64 encoded): NONE Minimum expected Diffie Hellman key size : 1024 bits %Please create RSA keys to enable SSH (and of atleast 768 bits for SSH v2).Īuthentication timeout: 120 secs Authentication retries: 3 To check, simply enter privilege mode and use the show ip ssh command: Products with (K9) in the image name e.g c2900-universal 2.bin, support strong encryption with 3DES/AES while (K8) IOS bundles support weak encryption with the outdated DES. Most modern Cisco routers support SSH, so this shouldn’t be a problem. The first step involves examining whether your Cisco router’s IOS supports SSH or not. SSH uses public key for authenticating the remote device and encrypt all data between that device and the workstation which makes it the best choice for public networks, unlike (telnet) which transmits data in plain text which subjects it to security threats, this makes (telnet) recommended for private networks only to keep the data uncompromised. SSH makes use of TCP port 22 which’s assigned to secure logins, file transfer and port forwarding. It’s an encrypted network protocol that allows users to safely access equipment via command line interface sessions. Secure Shell (SSH) provides a secure and reliable mean of connecting to remote devices.
We’ll show you how to check if SSH is supported by your IOS version, how to enable it, generate an RSA key for your router and finally configure SSH as the preferred management protocol under the VTY interfaces. This article shows how to configure and setup SSH for remote management of Cisco IOS Routers.