As per Relevance of the word broadcast, we have this rfc below:
Network Working Group D.
Request for Comments: 2644 Amaranth Networks Inc
Updates: 1812 August 1999
BCP: 34
Category: Best Current
Changing the Default for Directed Broadcasts in
Status of this
This document specifies an Internet Best Current Practices for
Internet Community, and requests discussion and suggestions
improvements. Distribution of this memo is unlimited
Copyright
Copyright (C) The Internet Society (1999). All Rights Reserved
1.
Router Requirements [1] specifies that routers must receive
forward directed broadcasts. It also specifies that routers MUST
an option to disable this feature, and that this option MUST
to permit the receiving and forwarding of directed broadcasts.
directed broadcasts have uses, their use on the Internet
appears to be comprised entirely of malicious attacks on
networks
Changing the required default for routers would help ensure
routers connected to the Internet do not add to the problems
present
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
document are to be interpreted as described in RFC 2119.
2.
Damaging denial of service attacks led to the writing of [2]
Ingress Filtering. Many network providers and corporate networks
endorsed the use of these methods to ensure their networks are
the source of such attacks
A recent trend in Smurf Attacks [3] is to target networks
permit directed broadcasts from outside their networks. By
directed broadcasts, these systems become "Smurf Amplifiers."
Senie Best Current Practice [Page 1]
RFC 2644 Default Change for Directed Broadcast August 1999
While the continued implementation of ingress filters remains
best way to limit these attacks, restricting directed
should also receive priority
Network service providers and corporate network operators are
to ensure their networks are not susceptible to directed
packets originating outside their networks
Mobile IP [4] had provisions for using directed broadcasts in
mobile node's use of dynamic agent discovery. While
implementations support this feature, it is unclear whether it
useful. Other methods of achieving the same result are documented
[5]. It may be worthwhile to consider removing the language on
directed broadcasts as Mobile IP progresses on the standards track
3.
Router Requirements [1] is updated as follows
Section 4.2.2.11 (d) is replaced with
(d) { , -1 }
Directed Broadcast - a broadcast directed to the specified
prefix. It MUST NOT be used as a source address. A router
originate Network Directed Broadcast packets. A router MAY have
configuration option to allow it to receive directed
packets, however this option MUST be disabled by default, and
the router MUST NOT receive Network Directed Broadcast
unless specifically configured by the end user
Section 5.3.5.2, second paragraph replaced with
A router MAY have an option to enable receiving network-prefix
directed broadcasts on an interface and MAY have an option
enable forwarding network-prefix-directed broadcasts.
options MUST default to blocking receipt and blocking
of network-prefix-directed broadcasts
4. Security
The goal of this document is to reduce the efficacy of certain
of denial of service attacks
5.
[1] Baker, F., "Requirements for IP Version 4 Routers", RFC 1812,
June 1995.
Senie Best Current Practice [Page 2]
RFC 2644 Default Change for Directed Broadcast August 1999
[2] Ferguson, P. and D. Senie, "Ingress Filtering", RFC 2267,
1998.
[3] See the pages by Craig Huegen at
http://www.quadrunner.com/~chuegen/smurf.txt, and the
advisory at: http://www.cert.org/advisories/CA-98.01.smurf.
[4] Perkins, C., "IP Mobility Support", RFC 2002, October 1996.
[5] P. Calhoun, C. Perkins, "Mobile IP Dynamic Home
Allocation Extensions", Work in Progress
6.
The author would like to thank Brandon Ross of Mindspring and
Montenegro of Sun for their input
7. Author's
Daniel
Amaranth Networks Inc
324 Still River
Bolton, MA 01740
Phone: (978) 779-6813
EMail: dts@senie.
Senie Best Current Practice [Page 3]
RFC 2644 Default Change for Directed Broadcast August 1999
8. Full Copyright
Copyright (C) The Internet Society (1999). All Rights Reserved
This document and translations of it may be copied and furnished
others, and derivative works that comment on or otherwise explain
or assist in its implementation may be prepared, copied,
and distributed, in whole or in part, without restriction of
kind, provided that the above copyright notice and this paragraph
included on all such copies and derivative works. However,
document itself may not be modified in any way, such as by
the copyright notice or references to the Internet Society or
Internet organizations, except as needed for the purpose
developing Internet standards in which case the procedures
copyrights defined in the Internet Standards process must
followed, or as required to translate it into languages other
English
The limited permissions granted above are perpetual and will not
revoked by the Internet Society or its successors or assigns
This document and the information contained herein is provided on
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED,
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
Funding for the RFC Editor function is currently provided by
Internet Society
Senie Best Current Practice [Page 4]
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