mbedtls Network Stream Driver¶

Driver Name:	mbedtls
Author:	Stéphane Adenot <stephane.adenot@csgroup.eu>
Available since:	8.2512

Purpose¶

This network stream driver implements a TLS protected transport via the MbedTLS 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.
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 auth mode.

CheckExtendedKeyPurpose¶

off - by default this binary argument is turned off, which means that Extended Key Usage extension of certificates is ignored in cert validation.
on - if you turn this option on, it will check that peer’s certificate contains the value for “TLS WWW Client” or “TLS WWW Server” respectively, depending whether we are on sending or receiving end of a connection.

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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