Date: 30 Nov 1983 0310 PST
From: Eric P. Scott <EPS at JPL-VAX>
Reply-To: EPS at JPL-VAX
To:   TCP-IP at SRI-NIC
Re:   Not an RFC inspired by a somewhat infamous computer game




Network Hacking Group					     E. P. Scott
Request for Kludges: XXX					     JPL
							  November, 1983
Updates: RFC 821


			 SMTP POLYMORPH COMMAND

Preface

   The purpose of this document is to present a partial workaround for
   an anticipated future problem in the ARPA Internet.  It is hoped that
   it will prove unnecessary to adopt such an overtly ridiculous
   strategy as a practical means of preserving connectivity.  The views
   expressed are the author's own and do not necessarily reflect those
   of NASA, the Jet Propulsion Laboratory, or the California Institute
   of Technology.  Treat them as satirical in nature.

Introduction

   Current plans call for the activation of "access control filters" in
   the six IP gateways that bridge MILNET and ARPANET on February 1,
   1984 [1].  In most cases communications will be restricted to mail
   only.  Sites such as ours which are in the wrong Community Of
   Interest vis a vis the sites they need to communicate with because
   the politics run counter to legitimate research needs will be unable
   to participate as functional nodes after this date.  A trivial
   solution is of course to abandon the plan to segregate the two
   networks [2].  Assuming that this does not happen and the controls go
   into effect on schedule, it will be necessary to defeat the
   "protection" offered in order to "stay in business" (unless the
   Powers That Be can be convinced to put us back on the other side of
   the fence before then).  Even so, other sites share a similar plight.

Description

   I propose to implement an extension to the SMTP protocol [3] that
   would allow services such as Telnet [4] to be accessed via port 25.
   The extension consists of the new command POLY which accepts as its
   parameter a keyword identifying the service desired.  Successful
   execution of POLY returns a 250 reply and replaces the SMTP server.
   It is assumed that POLY would be given as the first command in a
   session in order to avoid considering the implications of arbitrary
   placement.  A typical scenario might look like:

	@TELNET
	TELNET>INTERNET (HOST) JPL-VLSI (ON PORT) 25
	 Trying... Open
	220 JPL-VLSI.DDN SMTP Service
	POLY TELNET
	250 Toto, I don't think we're in SMTP anymore!
	JPL VLSI Design Center VAX...


Scott								[Page 1]



SMTP Polymorph Command						 RFK XXX


Syntax

	POLY <SP> <string> <CRLF>

Replies

	S: 250
	E: 500, 501, 502, 503, 504, 421

Concluding Comments

   "Polymorph" commands are nothing new; SMTP's TURN can be considered
   one; perhaps a better example is the Telnet SUPDUP Option [5].

   FTP presents a special problem since data is not transmitted over
   the telnet connection.

   This won't help (most) TAC users.

References

   [1]	DDN Program Management Office, "Further Details on the MILNET/
	ARPANET Split," in DDN Newsletter no. 28, Network Information
	Center, SRI International, July 1983.

   [2]	Muuss, M., "On the Undesirability of `Mail Bridges' as a
	Security Measure," in TCP-IP Digest, vol. 2, no. 18, BRL,
	October 1983.

   [3]	Postel, J., "Simple Mail Transfer Protocol," RFC 821, USC/
	Information Sciences Institute, August 1982.

   [4]	Postel, J. and J. Reynolds, "Telnet Protocol Specification,"
	RFC 854, USC/Information Sciences Institute, May 1983.

   [5]	Crispin, M., "Telnet SUPDUP Option," RFC 736, NIC 42213,
	Stanford Artificial Intelligence Laboratory, October 1977.














Scott								[Page 2]