Two-Factor Authentication for LINUX SSH

Before learning the two-factor authentication for LINUX SSH, let’s have a small overview of LINUX. Linux server is one of the widely and popularly used servers by the organizations across the world. It constitutes near about 67% of public servers. 37% of websites use LINUX. It is preferred to be one of the best and efficient servers to carry out the large volume of web process and transactions at no downtime.

Linux server is much more reliable and scalable and makes use of SSH protocol to ensure login and access to remote servers. However, SSH involves the usage of the password and solely password-based authentication means the invitation to security threats and breaches. Passwords, these days are no more secure as these can be easily hacked, cracked or stolen using multiple methods.

In addition, availability and processing of a diverse range of data including financial and confidential data make LINUX more favourite amongst the hackers and attackers. Protecting SSH logins merely with passwords may put your or your organization’s data on stake.

FairWare Ransomware targeting LINUX computers
FairWare Ransomware targeting LINUX computers

Click SSH security to read and learn more about the LINUX SSH.

Why Two-Factor Authentication for LINUX SSH?

SSH or Secure Shell is a protocol that enables user to login and access remotely located system & servers, securely over an unsecured network. SSH not only encrypts the remote sessions, but also deliver better authentication, using cryptographic keys- public key and private key.

As such the combination of password and the cryptographic keys may seem to be a viable and stronger authentication option but it’s not, and the reason could be any of the following:

  • Cryptographic key (private key) may not be password protected and could be easily stolen.
  • Less complex or simple password by the user in encrypting & protecting private key.
  • System or device where the user has saved or stored the private key may be vulnerable to theft and other related compromises.

As discussed above, passwords are no longer effective to get your servers protected from intrusion and different security breaches. In addition, the introduction of concepts like BYOD (Bring your own Device) have brought organization’s (Linux)servers more at risk by granting privilege to employees in accessing organization’s network, server and data using their personal devices like laptops, tablets and smartphones.

Two-Factor Authentication: Improving LINUX SSH security

Adopting and implementing two-factor authentication to LINUX SSH enforces the user to prove his/her credibility twice during the dual authentication check. With 2FA, user’s identity is verified and validated, using “What he/she knows” and “What he/she have”.

Two Factor Authentication for LINUX SSH
Two Factor Authentication for LINUX SSH

What does a user know, is username and password.

What a user may have, is security token/code.

2FA places the door of token-based authentication between a user and the protected server. Anybody can knock on this door but only the authorized user having that secret code can open this door.

Is it beneficial to secure all servers using 2FA?

Implementing 2FA protection have always proven to be beneficial irrespective of individual or organizational needs. 2FA may be implemented across all servers present within the organizational boundaries. But that will create complexity in managing, accessing and using those servers.

It is pertinent to mention that the servers are protected and secured by the different and versatile types of firewalls, VPNs and other network security tools. However, all these network security methods will avoid and prevents intrusion within the organizational network boundaries only.

Public-facing servers (usually very few) are open to access and explore by any of the users, remotely over an unsecured network using SSH outside the organization’s secured network. As such these public-facing servers are most prone to intrusion & data-theft, and requires utmost protection. Thus, 2FA implementation may be restricted to public facing servers only.

In conclusion, it may be stated that servers are meant for storing and executing large amount of business & organizational data. Therefore, expecting fullest protection to servers merely with a password is not less than a fool’s paradise. Two-factor authentication is one of the easiest and convenient ways to ensure guaranteed and multi-layered protection to LINUX servers.

Multi-Factor Authentication Vs Two-Factor Authentication

The present information technology era has been perceiving rising and severe cyber-attacks, especially security and data breaches. Weak and stolen credentials and passwords may be seen as one of the prime reasons behind most of the intrusion and data breaches. Thus, it generated the need for either replacing or making the passwords based authentication more stronger and reliable. In the world of web and computer security, we all must have heard the terms Multi-factor authentication (MFA) and two-factor authentication (2FA) that are required to improve existing password-based security. However, most of the users find themselves confused over the differences between 2FA and MFA like what’s the difference between them, which one to choose and many similar types of queries.

What is Two-Factor Authentication or 2FA?

As the name suggests, two-Factor authentication defines the mechanism for verifying and validating the user’s login credibility via two different authentication layers. The first layer of authentication check involves user’s credential check i.e. username and password. On successfully passing the password-based authentication, the user is directed to the second layer of authentication check, where he/she needs to enter the security hardware or software tokens to get themselves authenticated. and finally, the authorized user gets the access.

2FA Working

Two-Factor authentication check and validates the login based on following attributes:

Something that a user knows: This may include registered credentials like username and password or pin. A user knowing correct or incorrect password may or may not get him/herself authenticated in the first security check.

Something that a user has: This generally, refers to security codes or OTPs as hardware or software tokens, which are received or generated on their mobile or any other registered hardware devices. During this authentication check, a user needs to provide the security token or code to verify his/her credibility in the final authentication check and accordingly gets access.

Learn some tips about 2FA in our blog- Tips for Using Two Factor Authentication Method.

What is Multi-Factor Authentication or MFA?

You may interpret the meaning of MFA through its name itself “Multi-factor authentication” i.e. authentication check involving multiple factors. In layman’s language, multi-factor authentication could be seen as the process of authenticating the user’s login veracity through multiple authentication layers, where each layer consists of different and unique parameters to verify and validate the user authenticity.

MFA working

Basically, in MFA, a user is made to go through a defined sequence of authentication checks, starting from initial authentication check based on the password to more stringent authentications. These multiple and stringent authentication checks comprise of different factors to verify and validate the user authorization.

  • Something user knows– password
  • Something user have– security tokens
  • Something user is– biometric scan
  • Location of the user– geographical location or coordinates
  • …….
  • …….
  • and so on

difference between mfa and 2fa

What’s the difference between MFA and 2FA?

Nothing. The difference between MFA and 2FA is very minute in terms of authentication layers and factors used, which may be considered negligible. Basically, 2FA is a subset of MFA but vice-versa is not true. Authentication checks involving more than one authentication layers/parameters falls under the category of MFA. As such, 2FA, 3FA, 4FA,……are nothing but the sub-categories of MFA.

In short, every 2FA is a Multi-factor authentication, but all multi-factor authentications are not necessarily 2FA.

In the light of the above discussion, it may be stated that the selection between 2FA and MFA (2FA and above) should be based on the scope, boundary, data sensitivity, need of securing small, medium or large-sized infrastructure and many similar factors. It should be noted that more the authentication checks we have, better will be the security, but at the same time the user should not feel tiresome/difficult in getting him/herself authenticated.

2FA solutions like REVE Secure guarantees stronger and uncompromising security with their powerful two-factor authentication. Visit REVE Secure, to learn more.