[GTER] Fwd: The Angelic Bit vs the Evil Bit

[Omar Kaminski]

http://catless.ncl.ac.uk/Risks/22.66.html#subj2

The Angelic Bit vs the Evil Bit
Drew Dean <ddean at csl.sri.com> 
Tue, 1 Apr 2003 10:00:01 +1000
Steve Bellovin's proposed RFC 3514 finds a very constructive use for the
last unused bit in the IPv4 header.  In his proposal, the unused bit is
sometimes affectionately referred to as the "evil" bit, although that naming
convention reflects a fundamentally *pessimistic* world view.  We prefer an
*optimistic* world view, and therefore propose that this last bit should be
used for the "angelic" bit.  Our proposed semantics for the angelic bit are
as follows:

  0x1  The angelic bit is set.  All routers, firewalls, switches, and any
       other network devices MUST forward this packet to its indicated
       destination.  This packet MUST NOT have any undesirable effect on any
       network device.  Anyone who improperly sets the angelic bit on any
       packet SHALL be subject to divine retribution.  Civil authorities MAY
       subject the perpetrator to any punishment provided for in applicable
       law.

  0x0  The angelic bit is reset.  All routers, firewalls, switches, and other
       network devices MAY filter this packet according to any policy they
       deem fit.  This packet MAY have undesirable effects if forwarded.
       The sender of the packet SHALL NOT be subject to divine retribution
       in case of undesirable effects.  Civil authorities MAY subject the
       perpetrator to punishment provided for in applicable law.

NB: The angelic bit may have miraculous properties in face of network links
severed by backhoes; however, this SHALL NOT relieve the router of its
responsibilities.

Yours for a more genteel Internet, Drew Dean
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