[Syslog] Missing dead peer detection in DTLS

[Gerhard Muenz <[e-mail]>]

Hi,

This mail goes to the ipfix and syslog mailing lists in order to
summarize the common issues regarding DTLS.

IPFIX specifies support of DTLS as mandatory for transport over UDP and
SCTP in RFC5101. In SYSLOG, it is intended to standardize DTLS for
transport over UDP.

In IPFIX, we have a first implementation of IPFIX-over-DTLS/UDP, and we
will have a first implementation of IPFIX-over-DTLS/SCTP very soon.
During this implementation effort, we found that the current
specification of DTLS/UDP has a severe flaw when used with
unidirectional protocols (like IPFIX): The sender cannot recognize if
the receiver has crashed and lost the DTLS state.

We discuss this issue in a draft:
http://tools.ietf.org/html/draft-mentz-ipfix-dtls-recommendations-00
http://www.ietf.org/proceedings/75/slides/ipfix-6.pdf

I've had a look at draft-feng-syslog-transport-dtls-01 and
draft-petch-gerhards-syslog-transport-dtls-02. It seems that this
problem has not yet been covered, although the problem should be the
same for SYSLOG.

As a solution, the DTLS Heartbeat Extension has been proposed very recently:
http://tools.ietf.org/html/draft-seggelmann-tls-dtls-heartbeat-00
A feature patch for OpenSSL is available:
http://sctp.fh-muenster.de/dtls-patches.html#features

So, I think that we should support this standardization initiative as it
solves our problem. For IPFIX and SYSLOG over DTLS/UDP, we then can
specify that the DTLS Heartbeat Extension MUST be implemented.

Dan suggested to have a single document solving the DTLS issues
regarding unidirectional protocols. I think that such a document is not
needed if we have DTLS Heartbeat Extension.

Regards,
Gerhard

-- 
Dipl.-Ing. Gerhard Münz
Chair for Network Architectures and Services (I8)
Department of Informatics
Technische Universität München
Boltzmannstr. 3, 85748 Garching bei München, Germany
Phone:  [phone]       Fax: [phone]
E-mail: [e-mail]    WWW: http://www.net.in.tum.de/~muenz