BCP 156, RFC 6056 on Recommendations for Transport-Protocol Port Randomization

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        BCP 156        
        RFC 6056

        Title:      Recommendations for Transport-Protocol Port 
                    Randomization 
        Author:     M. Larsen, F. Gont
        Status:     Best Current Practice
        Stream:     IETF
        Date:       January 2011
        Mailbox:    michael.larsen@tieto.com, 
                    fernando@gont.com.ar
        Pages:      29
        Characters: 63913
        See Also:   BCP0156

        I-D Tag:    draft-ietf-tsvwg-port-randomization-09.txt

        URL:        http://www.rfc-editor.org/rfc/rfc6056.txt

During the last few years, awareness has been raised about a number
of "blind" attacks that can be performed against the Transmission
Control Protocol (TCP) and similar protocols.  The consequences of
these attacks range from throughput reduction to broken connections
or data corruption.  These attacks rely on the attacker's ability to
guess or know the five-tuple (Protocol, Source Address, Destination
Address, Source Port, Destination Port) that identifies the transport
protocol instance to be attacked.  This document describes a number
of simple and efficient methods for the selection of the client port
number, such that the possibility of an attacker guessing the exact
value is reduced.  While this is not a replacement for cryptographic
methods for protecting the transport-protocol instance, the
aforementioned port selection algorithms provide improved security
with very little effort and without any key management overhead.  The
algorithms described in this document are local policies that may be
incrementally deployed and that do not violate the specifications of
any of the transport protocols that may benefit from them, such as
TCP, UDP, UDP-lite, Stream Control Transmission Protocol (SCTP),
Datagram Congestion Control Protocol (DCCP), and RTP (provided that
the RTP application explicitly signals the RTP and RTCP port
numbers).  This memo documents an Internet Best Current Practice.

This document is a product of the Transport Area Working Group Working Group of the IETF.

BCP: This document specifies an Internet Best Current Practices for the
Internet Community, and requests discussion and suggestions for 
improvements. Distribution of this memo is unlimited.

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