SSL Connection Test Tools

TL;DR

OpenSSL is a powerful command-line tool for testing SSL connections. For a simpler graphical interface, use online SSL checkers or dedicated application tools like Burp Suite.

Testing Your SSL Connection: A Step-by-Step Guide

1. Understand Why You Need to Test

Before diving into tools, know what you’re checking for:

• Certificate Validity: Is your certificate expired or about to expire?
• Chain of Trust: Are all the necessary intermediate certificates installed correctly?
• Protocol Support: Does your server support modern protocols like TLS 1.3 and avoid older, insecure ones like SSLv3?
• Cipher Suite Strength: Are strong encryption algorithms being used?

Using OpenSSL (Command Line)

OpenSSL is pre-installed on many Linux and macOS systems. Windows users may need to download it from a reputable source.

To test a connection, use the following command:

openssl s_client -connect yourdomain.com:443

Replace yourdomain.com with your actual domain name.

• Interpreting the Output: Look for lines indicating:
  • Certificate details: Check the ‘Valid From’ and ‘Valid To’ dates.
  • Protocol version: Ensure it’s TLS 1.2 or higher (TLS 1.3 is preferred).
  • Cipher suite: Look for strong ciphers like ECDHE-RSA-AES256-GCM-SHA384. Avoid anything with ‘RC4’ or older algorithms.

Online SSL Checkers (Easy Option)

Several websites offer free SSL connection tests:

• SSL Labs: https://www.ssllabs.com/ssltest/ (Very detailed analysis)
• DigiCert SSL Installation Diagnostics Tool: https://www.digicert.com/ssl-installation (Simple and user-friendly)
• Qualys SSL Labs: Similar to SSL Labs, provides in-depth reports.

Simply enter your domain name, and the tool will perform a comprehensive check.

Using Burp Suite (For Developers)

Burp Suite is a popular web security testing toolkit. It provides a graphical interface for intercepting and analyzing SSL connections.

• Install and Configure: Download and install Burp Suite Community Edition or Professional. Configure your browser to use Burp as a proxy.
• Intercept the Connection: Browse to your website through Burp.
• Analyze in Burp: Burp will display detailed information about the SSL connection, including certificate details, protocol version, and cipher suites.

Testing with Code (Example – Python)

You can also test SSL connections programmatically using libraries like ssl in Python.

import ssl
import socket

host = 'yourdomain.com'
port = 443

context = ssl.create_default_context()

try:
    with socket.create_connection((host, port)) as sock:
        with context.wrap_socket(sock, server_hostname=host) as ssock:
            print(ssock.version())
except Exception as e:
    print(f"Error: {e}")

Replace yourdomain.com with your domain.

Common Issues and Fixes

• Certificate Not Trusted: Ensure your certificate is issued by a trusted Certificate Authority (CA).
• Expired Certificate: Renew your SSL certificate before it expires.
• Missing Intermediate Certificates: Install all intermediate certificates on your server.
• Weak Cipher Suites: Configure your server to use strong cipher suites and disable older, insecure ones.