# On Slackware, I get the error: Cipher algorithm 'BF-CBC' not found (OpenSSL)

**NOTE: this article is very outdated. Modern OpenVPN negotiates ciphers between peers and --cipher is a no-op since OpenVPN 2.6. As such you're unlikely to encounter this issue anymore.**

By default, OpenVPN uses the *blowfish* cipher for tunnel encryption. For some reason, some versions of Slackware have an OpenSSL library built without Blowfish cipher support.

The fix is either:
- Rebuild the OpenSSL library to include blowfish, or
- Use the `--cipher` option to choose a different cipher. The command `openvpn --show-ciphers` will show the available ciphers. For example `--cipher DES-EDE3-CBC` will select Triple-DES encryption.