The SSH (“Secure Shell”) protocol is a method for secure remote login from one system to another. Sysadmins and users use a secure channel over an unsecured network in a client-server architecture format for connecting an SSH client with an SSH server. Security ssh server is an important task. There is a tool called ssh_scan from Mozilla which act as a prototype SSH configuration and policy scanner for your SSHD.
Two factor authentication is increasingly becoming a strongly recommended way of protecting user accounts in web applications from attackers by requiring a second method of authentication in addition to the standard username and password pair.
Although two factor authentication can encompass a wide range of techniques like biometrics or smart cards, the most commonly deployed technique in web applications is the one time password. If you have used applications like Gmail, you are probably familiar with the one time password generated by the Google Authenticator app that’s available on iOS or Android devices.
The algorithm used for the one time password in the Google Authenticator app is known as the Time-based One-Time Password (TOTP) algorithm. The TOTP algorithm is a standard algorithm approved by the IETF in (RFC 6238) totp-rfc.