Network Working Group Jon Postel (SRI-ARC)
Request for Comments: 706 Nov 1975
NIC #33861
On the Junk Mail Problem
- In the ARPA Network Host/IMP interface protocol there is no
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- mechanism for the Host to selectively refuse messages. This means
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- that a Host which desires to receive some particular messages must
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- read all messages addressed to it. Such a Host could be sent many
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- messages by a malfunctioning Host. This would constitute a denial of
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- service to the normal users of this Host. Both the local users and
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- the network communication could suffer. The services denied are the
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- processor time consumed in examining the undesired messages and
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- rejecting them, and the loss of network thruput or increased delay
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- due to the unnecessary busyness of the network.
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- It would be useful for a Host to be able to decline messages from
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- sources it believes are misbehaving or are simply annoying. If the
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- Host/IMP interface protocol allowed the Host to say to the IMP
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- "refuse messages from Host X", the IMPs could discard the unwanted
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- messages at their earliest opportunity returning a "refused" notice
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- to the offending Host.
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- How the IMPs might do this is an open issue -- here are two
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- possibilities:
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- The destination IMP would keep a list (per local Host) of sources
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- to refuse (this has the disadvantage of keeping the network
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- busy).
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- The destination IMP on receiving the "refuse messages from Host
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- X" message forwards the message to the source IMP (the IMP local
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- to Host X). That IMP keeps a list (per local Host) of
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- destinations that are refusing messages from this source Host.
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- This restriction on messages might be removed by a destination Host
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- either by sending a "accept messages from Host X" message to the
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- IMP, or by resetting its Host/IMP interface.
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- A Host might make use of such a facility by measuring, per source,
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- the number of undesired messages per unit time, if this measure
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- exceeds a threshold then the Host could issue the "refuse messages
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- from Host X" message to the IMP.
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