# openssl Network Stream Driver

Driver Name: | ossl
Author: | Andre Lorbach <alorbach@adiscon.com>
Available since: | 8.36.0

## Purpose

This network stream driver implements a TLS protected transport via the OpenSSL library.

## Supported Driver Modes

- 0 - unencrypted transmission (just like ptcp driver)

- 1 - TLS-protected operation

Note

Mode 0 does not provide any benefit over the ptcp driver. This mode exists for technical reasons, but should not be used. It may be removed in the future.

## Supported Authentication Modes

- anon - anonymous authentication as described in IETF’s draft-ietf-syslog-transport-tls-12 Internet draft

- x509/fingerprint - certificate fingerprint authentication as described in IETF’s draft-ietf-syslog-transport-tls-12 Internet draft. The fingerprint must be provided as the SHA1 or the SHA256 hex string of the certificate. Multiple values must be separated by comma (,). A valid configuration would be e.G.

      StreamDriverPermittedPeers="SHA256:10:C4:26:1D:CB:3C:AB:12:DB:1A:F0:47:37:AE:6D:D2:DE:66:B5:71:B7:2E:5B:BB:AE:0C:7E:7F:5F:0D:E9:64,SHA1:DD:23:E3:E7:70:F5:B4:13:44:16:78:A5:5A:8C:39:48:53:A6:DD:25"

- x509/certvalid - certificate validation only. x509/certvalid is a nonstandard mode. It validates the remote peers certificate, but does not check the subject name. This is weak authentication that may be useful in scenarios where multiple devices are deployed and it is sufficient proof of authenticity when their certificates are signed by the CA the server trusts. This is better than anon authentication, but still not recommended. Known Problems

- x509/name - certificate validation and subject name authentication as described in IETF’s draft-ietf-syslog-transport-tls-12 Internet draft

Note

“anon” does not permit to authenticate the remote peer. As such, this mode is vulnerable to man in the middle attacks as well as unauthorized access. It is recommended NOT to use this mode. A certificate / key does not need to be configured in this authmode.

Note

Anon mode changes in: v8.190 (or above)

- Anonymous Ciphers (DH and ECDH) are available in ANON mode.

- Server does not require a certificate anymore in anon mode.

- If Server has a certificate and the Client does not, the highest possible ciphers will be selected.

- If both Server and Client do not have a certificate, the highest available anon cipher will be used.

## PrioritizeSAN

- off - by default this binary argument is turned off, which means that validation of names in certificates goes per older RFC 5280 and either Subject Alternative Name or Common Name match is good and connection is allowed.

- on - if you turn this option on, it will perform stricter name checking as per newer RFC 6125, where, if any SAN is found, contents of CN are completely ignored and name validity is decided based on SAN only.

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© 2008–2025 Rainer Gerhards and others. Licensed under the Apache License 2.0.