Unlocking OpenVPN: A Guide to Bypass Cipher and TLS Errors for Seamless Connections
With the newer versions of OpenVPN (esp. 2.6), the older versions of TLS and encryption protocols are not supported by default. Although it is always the better option to update the VPN config to match with the latest security protocols, it is not always possible to do that without sufficient planning as changing the OpenVPN configuration means every single user needs to re-download the configuration file for their connection to work. And that required extensive planning and discussions which takes very long to complete.
Below are some errors that can be configured to bypass the restrictions on the newer versions of OpenVPN.
1. TLS Error
VERIFY ERROR depth-O. error-CA signature digest algorithm too weak
OpenSSL: error:1416F086:SSL routines:tls_process_server_certificate:certificate verify failed
TLS_ERROR: BIO read error tls_read_plaintext error
If you encounter the above error, add the below line at the top of the configuration:
tls-cipher “DEFAULT:@SECLEVEL=0”
2. Cipher Error
OPTIONS ERROR: failed to negotiate cipher with server. Add the server’s cipher (‘AES-128-CBC’) to –data-ciphers (currently ‘AES-256-GCM:AES-128-GCM:CHACHA20-POLY1305’) if you want to connect to this server
For this error, please replace the line that starts with “CIPHER” with the below
–data-ciphers AES-128-CBC
3. TLS Version Unsupported
TLS error: Unsupported protocol. This typically indicates that client and server have no common TLS version enabled. This can be caused by mismatched tls-version-min and tls-version-max options on client and server. If your OpenVPN client is between v2.3.6 and v2.3.2 try adding tls-version-min 1.0 to the client configuration to use TLS 1.0+ instead of TLS 1.0 only
OpenSSL: error:0A000102:SSL routines::unsupported protocol
TLS_ERROR: BIO read tls_read_plaintext error
TLS Error: TLS object -> incoming plaintext read error
TLS Error: TLS handshake failed
Fatal TLS error (check_tls_errors_co), restarting
SIGUSR1[soft,tls-error] received, process restarting
MANAGEMENT: >STATE:1680529391,RECONNECTING,tls-error,,,,,
In this case, please add the below line towards the top of the config file:
tls-version-min 1.0
If none of these work, you can uninstall the existing OpenVPN client and re-install versions 2.5.8 or 2.5.9 which are available on the OpenVPN community download website.
Conclusion:
In conclusion, mastering the art of OpenVPN configuration is the key to achieving flawless and secure connections. By delving into the intricacies of cipher suites and TLS protocols, you’ve gained the tools to overcome potential errors that could hinder your VPN experience. With this guide as your compass, you’re now equipped to navigate the realm of OpenVPN with confidence, ensuring seamless connections that prioritize both privacy and performance. So, go ahead and boost the full potential of OpenVPN, transforming your online journey into a smooth and secure adventure.