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curl: (35) libressl/3.3.6: error:1404b42e:ssl routines:st_connect:tlsv1 alert protocol version

curl: (35) libressl/3.3.6: error:1404b42e:ssl routines:st_connect:tlsv1 alert protocol version

3 min read 19-12-2024
curl: (35) libressl/3.3.6: error:1404b42e:ssl routines:st_connect:tlsv1 alert protocol version

The error message "curl: (35) libressl/3.3.6: error:1404b42e:ssl routines:st_connect:tlsv1 alert protocol version" indicates a problem with the Secure Sockets Layer (SSL) or Transport Layer Security (TLS) connection between your system and the server you're trying to access using curl. This usually means your system is trying to use an outdated or unsupported TLS protocol version. Let's troubleshoot this.

Understanding the Error

The core of the problem lies in the incompatibility between your curl client's offered TLS version and the server's accepted versions. The error specifically mentions TLSv1, an older, insecure protocol version no longer supported by many modern servers. Servers are increasingly disabling older, vulnerable protocols to enhance security.

Common Causes and Solutions

Here are the most common reasons for this error and how to fix them:

1. Outdated OpenSSL/libressl Library

The error message points to libressl/3.3.6, which is your SSL/TLS library. An outdated library might lack support for newer, secure protocols.

  • Solution: Update your libressl library. The method depends on your operating system:
    • Debian/Ubuntu: sudo apt update && sudo apt upgrade libssl-dev (or a similar package name).
    • Fedora/CentOS/RHEL: sudo dnf update (or sudo yum update).
    • macOS (Homebrew): brew update && brew upgrade libressl
    • Other systems: Consult your distribution's documentation for updating packages. You may need to find the appropriate package manager (like pacman on Arch Linux) and update the libressl or openssl package.

2. Server-Side Restrictions

The server you're connecting to may explicitly disable TLSv1 and older protocols. This is a security best practice.

  • Solution: Unfortunately, you have little control over server-side settings. Contact the server administrator if you suspect this is the issue. In the meantime, consider alternative solutions (see below).

3. Firewall or Proxy Interference

Network firewalls or proxies might be interfering with the connection, blocking or modifying the TLS handshake.

  • Solution: Temporarily disable your firewall or proxy to see if that resolves the issue. If it does, configure your firewall/proxy to allow the necessary TLS traffic. This often involves specifying allowed ports (usually 443 for HTTPS).

4. Incorrect curl Configuration

While less common, misconfigurations within your curl settings could lead to this problem.

  • Solution: Try using the --tlsv1.2 or --tlsv1.3 option with your curl command to explicitly specify a supported TLS version:
    curl --tlsv1.2 https://www.example.com
    curl --tlsv1.3 https://www.example.com
    
    If one of these works, update your system's SSL/TLS library to ensure compatibility.

Advanced Troubleshooting Steps

If the above steps don't resolve the problem:

  • Check Server's SSL/TLS Configuration: Use tools like sslscan or online SSL checkers to examine the server's SSL/TLS settings and identify supported protocols.
  • Examine System Logs: Look for detailed error messages in your system's logs (e.g., /var/log/syslog on Linux) that might provide more clues.
  • Test with Different Browsers: Try accessing the website with a web browser. If the browser succeeds, the issue likely lies with your curl configuration or underlying libraries.

Preventing Future Occurrences

  • Keep your system's packages updated: Regularly update your operating system and its libraries, including OpenSSL or libressl.
  • Use a modern curl version: Ensure you're using a recent version of curl to take advantage of the latest SSL/TLS support.

By systematically working through these troubleshooting steps, you should be able to resolve the "curl: (35) libressl/3.3.6: error:1404b42e:ssl routines:st_connect:tlsv1 alert protocol version" error and successfully connect to the target server. Remember to prioritize security best practices by using up-to-date software and secure protocols.

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