TLS stands for Transport Layer Security. It is a protocol that is designed to ensure secure communication over a network.

It is considered as a standard best practice to implement this protocol while designing secure websites and applications.
Here at LinuxAPT, as part of our Server Management Services, we regularly help our Customers to perform related TLS queries.
In this context, we shall look into different methods of verifying if a web server supports TLS or not on Ubuntu 20.04.

Methods of Verifying if a Server Supports TLS or not on Ubuntu 20.04

To verify if a web server supports TLS or not, you can make use of any of the following two methods on a Ubuntu 20.04 system.

Method #1. Using the "Nmap" Utility on Ubuntu 20.04

"Nmap" is a very commonly used utility for discovering hosts and services on a network.
To use this utility for verifying if a server supports TLS or not on Ubuntu 20.04, you will have to perform the following steps:

i. Install the "Nmap" Utility on your Ubuntu 20.04 System
First, you need to install "Nmap" on your Ubuntu 20.04 system with the command shown below:

$ sudo apt install nmap

ii. Use the "Nmap" Utility for Verifying if a Server Supports TLS or not on Ubuntu 20.04
Now you can use this utility for verifying if a server supports TLS or not on Ubuntu 20.04 in the manner shown below:

$ nmap --script ssl-enum-ciphers –p 443 DomainNameOfServer

Here, you need to replace the DomainNameOfServer with the actual domain name of the server whose TLS support you want to verify.
For example, we have replaced it with "google.com" in our case to get:

$ nmap --script ssl-enum-ciphers –p 443 google.com

From the output, you will see that TLS is supported by our specified web server.

Method #2. Using the "OpenSSL" Tool on Ubuntu 20.04

"OpenSSL" is a feature-filled tool for transport layer security. For using this tool to verify if a server supports TLS or not on Ubuntu 20.04, you will have to perform the steps listed below:

i. Install the "OpenSSL" tool on your Ubuntu 20.04 System
First, you need to install the OpenSSL tool on your Ubuntu 20.04 system with the following command:

$ sudo apt install openssl

ii. Use the "OpenSSL" Tool for Verifying if a Server Supports TLS or not on Ubuntu 20.04
Now you can use this tool for verifying if a server supports TLS or not on Ubuntu 20.04 in the following manner:

$ sudo openssl s_client –connect DomainNameOfServer:443 –tls1_3

Here, you need to replace the DomainNameOfServer with the actual domain name of the server whose TLS support you want to verify.
For example, we have replaced it with "google.com" in our case.
Also, you can replace –tls1_3 with –tls1, -tls1_1, -tls1_2 for TLS version 1.0, 1.1, and 1.2 respectively to get:

$ sudo openssl s_client –connect google.com:443 –tls1_3

The output will show that TLS is supported by our specified web server.

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