One document matched: draft-eastlake-ip-mime-03.txt
Differences from draft-eastlake-ip-mime-02.txt
INTERNET-DRAFT D. Eastlake 3rd
Expires: December 2000 June 2000
IP over MIME
-- ---- ----
<draft-eastlake-ip-mime-03.txt>
Status of This Document
Distribution of this document is unlimited. Comments should be sent
to the author.
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet- Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
Abstract
The MIME encoding of IP packets is standardized so they can
conveniently be sent via MAIL, HTTP, etc. This may be convenient for
transmitting packets for analysis or for creating application level
tunnels.
Acknowledgement
Helpful suggestions from Matt Crawford and Mike Ditto have been
incorporated herein.
D. Eastlake 3rd [Page 1]
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Table of Contents
Status of This Document....................................1
Abstract...................................................1
Acknowledgement............................................1
Table of Contents..........................................2
1. Introduction............................................3
2. MIME Type Specification.................................4
3. Security Considerations.................................5
References.................................................6
Author's Address...........................................6
Expiration and File Name...................................7
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1. Introduction
The Internet Protocol (IP [RFC 791]) has been profiled for
transmission over a wide variety of media including Ethernet [RFC
894], point to point circuits [RFC 1661], FDDI [RFC 1390], and even
avian carriers [RFC 1149], etc. And one of the most popular encoding
and labeling (AKA, tagging and bagging) techniques defined for the
TCP/IP protocol suite is the MIME encoding [RFC 2045] used, for
example, in email, the web, and net news. This document rectifies the
omission that IP over MIME has not previously been specified.
An unambiguous MIME encoding for IP datagrams is useful in their
transmission for monitoring, analysis, debugging, or illustrative
purposes.
In addition, IP over MIME can be effective as one component in
creating application level tunnels that bypass firewall protections.
With the aid of cooperative software running within a firewall,
unrestricted, if slow, IP connectivity can be established.
The following diagram such a possible tunnel configuration:
Internet/Firwalls
SMTP/HTTP/... |
+-------------|------------+
| | |
Host A |h/w | h/w| Host B
+------------|----------+ | +---------|-------------+
| | | | | | |
| v | | | v |
| +-----------------+ | | | +-----------------+ |
| | Real IP | Stack | | | | Real | IP Stack | |
| +-----------------+ | | +-----------------+ |
| ^s/w ^ | | ^ s/w^ |
| : | | | | : |
| : v | | v : |
| : +------------+ | | +------------+ : |
| :.>| Application| | | |Application |<.: |
| +------------+ | | +------------+ |
+-----------------------+ +-----------------------+
Hosts A and B have hardware network interface (h/w) by which they can
communicate using IP. Applications capable of MIME encoding IP exist
on both Hosts. Through proper registry by the applications with
their local IP stack (which may require special privileges), real IP
stack to real IP stack IP connectivity can be established. Depending
on the addressing environments of Host A and B, incorporation of NAT
[RFC 1631] technology into these applications may also be helpful.
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2. MIME Type Specification
MIME media type name: APPLICATION
MIME subtype name: IP
Required parameters: (none)
Optional parameters: dilation, address
dilation=nnn
Typically IP packets will be MIME labeled for transmission over
email or other application level protocols. Such transmission
is normally slower than lower level network protocols. While
this is not much of a concern if a packet is just being
communicated for analysis, if such transmission is used to
establish connectivity, the sender of a datagram may wish to
advise the recipient of the estimated time dilation factor.
For example, if datagrams typically take around a second and
occsionally up to ten seconds end-to-end but it is more like a
minute and occasionally up to ten minutes if they are MIME
encoded in email, a "dilation=60" parameter would be
reasonable. Although IP and TCP are defined as timing
idependent protocols, many implementations actually have
timeouts built in. An effective technique in some cases to
defeat these timeouts is to repeatedly resend the last packet
received. This is, if a MIME encoded TCP packet is being sent
from Host A to Host B in the figure above where the
applications are gatewaying the packets to the real IP stack,
repeated transmisison of this packet by the application on Host
B to the stack may stave off timeouts. Similarly, the repeated
transmission to the real IP stack on Host A of the last reply
TCP packet may stave off timeouts there.
address=xxx/length
Full, if slow, IP connectivity via an application level
protocol such as SMTP [RFC 821, 822], in the absence of NAT
technology, might require that routing and/or interface entries
be installed at each end. This parameter enables the sender to
indicate what address mask and value it wishes to have
installed in routing and/or interface tables at the receiver
host or site so as to accomplish this. It requests that return
traffic matching the length number of upper bits of address
would be routed back to the sender of the APPLICATION/IP object
via the same application level protocol. A receiver of such an
APPLICATION/IP object with an address= parameter might
reasonably require that it be authenticated as meeting their
policy as to whom they would install routing on behalf of. For
example, they could ignore address= parameters unless the
APPLICATION/IP object was wrapped in an acceptable
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MULTIPART/SIGNED [RFC 1847] authentication.
Examples:
address="10.100.1.10/32"
address="1080:0:0:0:8:800:200C:4171/116"
Encoding considerations: Becasue of the binary nature of the body,
BASE64 transfer encoding should normally be used.
Security considerations: Care should be taken under any circumstance
where APPLCIATION/IP content can be treated as a "live" packet.
MULTIPART/ENCRYPTED [RFC 1847] may be used to further disguise
MIME packaged IP traffic.
Interoperability considerations: See [draft-eastlake-ip-mime-*.txt].
MULTIPART/MIXED [RFC 2046] may be used to package multiple IP
datagrams together.
Published specification: See [draft-eastlake-ip-mime-*.txt].
Applications which use this media type: Not yet in use.
Additional information: (none)
Person & email address to contact for further information:
Donald E. Eastlake 3rd, dee3@torque.pothole.com
Intended usage: LIMITED USE
Author/Change controller: IETF
3. Security Considerations
See security considerations in Section 2 above.
The APPLICATION/IP MIME type is particularly suitable as an
illustration of the weakness of the "crunchy outside, soft interior"
security model which places undue dependence on firewalls or similar
perimeter security. It would require a possibly privileged
accomplice or some other weakness to install code within a security
perimeter that would actually process incoming APPLICATION/IP data;
however, once this is done, general, if slow, IP connectivity can
normally be established because HTTP, email, and the like are
typically given free passage through firewalls.
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References
RFC 791 - "Internet Protocol.", J. Postel, Sep-01-1981.
RFC 821 - "Simple Mail Transfer Protocol", J. Postel, Aug-1982.
RFC 822 - "Standard For The Format Of ARPA Internet Text Messages",
D. Crocker, Aug-13-1982.
RFC 894 - "Standard for the transmission of IP datagrams over
Ethernet networks", C. Hornig, Apr-01-1984.
RFC 1149 - "Standard for the transmission of IP datagrams on avian
carriers", D. Waitzman, Apr-01-1990.
RFC 1390 - "Transmission of IP and ARP over FDDI Networks", D. Katz,
January 1993.
RFC 1631 - "The IP Network Address Translator (NAT)", K. Egevang, P.
Francis, May 1994
RFC 1661 - "The Point-to-Point Protocol (PPP)", W. Simpson, July
1994.
RFC 1847 - "Security Multiparts for MIME: Multipart/Signed and
Multipart/Encrypted", J. Galvin, S. Murphy, S. Crocker, N. Freed,
October 1995.
RFC 2045 - "Multipurpose Internet Mail Extensions (MIME) Part One:
Format of Internet Message Bodies", N. Freed & N. Borenstein,
November 1996.
RFC 2046 - " Multipurpose Internet Mail Extensions (MIME) Part Two:
Media Types", N. Freed, N. Borenstein, November 1996.
Author's Address
Donald E. Eastlake, 3rd
140 Forest Avenue
Hudson, MA 01749 USA
Telephone: +1 978-562-2827 (h)
+1 508-261-5434 (w)
fax: +1 508-261-4447 (w)
email: dee3@torque.pothole.com
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Expiration and File Name
This draft expires December 2000.
Its file name is draft-eastlake-ip-mime-03.txt.
D. Eastlake 3rd [Page 7]
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