Installation of OpenSSH in Linux

To install OpenSSH, open a terminal and run the following commands with superuser permissions.

On Ubuntu/Debian/Linux Mint

$ sudo apt-get install openssh-server openssh-client

On RHEL/Centos/Fedora

Type the following yum command to install openssh client and server.

# yum -y install openssh-server openssh-clients

Configuration of OpenSSH

It’s time to configure our OpenSSH behaviour through the ssh config file, but before editing the /etc/ssh/sshd_config file we need to backup a copy of it, so in case we make any mistake we have the original copy.

Open a terminal and run the following command to make a copy of the original sshd configuration file.

$ sudo cp /etc/ssh/sshd_config  /etc/ssh/sshd_config.original_copy

As you can see from the command I typed, I added the original_copy suffix, so every time I see this file I know it is an original copy of the sshd config file.

Scanning Cisco IOS 

Refer the following https://www.cisco.com/c/en/us/support/docs/security-vpn/secure-shell-ssh/4145-ssh.html to configure the Cisco IOS Router for scanning