Recommendations for Transport Port Uses
draft-ietf-tsvwg-port-use-04
The information below is for an old version of the document.
| Document | Type | Active Internet-Draft (tsvwg WG) | |
|---|---|---|---|
| Author | Dr. Joseph D. Touch | ||
| Last updated | 2014-05-14 | ||
| Replaces | draft-touch-tsvwg-port-use | ||
| Stream | Internet Engineering Task Force (IETF) | ||
| Formats | plain text htmlized pdfized bibtex | ||
| Reviews |
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| Stream | WG state | WG Document | |
| Document shepherd | Gorry Fairhurst | ||
| IESG | IESG state | I-D Exists (IESG: Dead) | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | Spencer Dawkins | ||
| Send notices to | tsvwg-chairs@tools.ietf.org, draft-ietf-tsvwg-port-use@tools.ietf.org |
draft-ietf-tsvwg-port-use-04
TSVWG J. Touch
Internet Draft USC/ISI
Intended status: Best Current Practice May 14, 2014
Expires: November 2014
Recommendations for Transport Port Uses
draft-ietf-tsvwg-port-use-04.txt
Status of this Memo
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Abstract
This document provides recommendations to application and service
designers on how to use the transport protocol port number space to
help in its preservation.
Table of Contents
1. Introduction...................................................2
2. Conventions used in this document..............................2
3. History........................................................3
4. Current Port Use...............................................4
5. What is a Port?................................................5
6. Conservation...................................................6
6.1. Firewall and NAT Considerations...........................7
7. How to Use Assigned Ports......................................8
7.1. Is a port assignment necessary?...........................8
7.2. How Many Ports?..........................................10
7.3. Picking a Port Number....................................10
7.4. Support for Security.....................................11
7.5. Support for Future Versions..............................12
7.6. Transport Protocols......................................13
7.7. When to Request an Assignment............................14
7.8. Squatting................................................15
7.9. Other Considerations.....................................16
8. Security Considerations.......................................16
9. IANA Considerations...........................................16
10. References...................................................16
10.1. Normative References....................................16
10.2. Informative References..................................17
11. Acknowledgments..............................................19
1. Introduction
This document provides information and advice to system designers on
the use of transport port numbers and services. It provides a
detailed historical background of the evolution of transport port
numbers and their multiple meanings. It also provides specific
recommendations on how to use assigned ports.
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [RFC2119].
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In this document, these words will appear with that interpretation
only when in ALL CAPS. Lower case uses of these words are not to be
interpreted as carrying RFC-2119 significance.
In this document, the characters ">>" preceding an indented line(s)
indicates a compliance requirement statement using the key words
listed above. This convention aids reviewers in quickly identifying
or finding the explicit compliance requirements of this RFC.
3. History
The term 'port' was first used in [RFC33] to indicate a simplex
communication path from an individual process. At a meeting
described in [RFC37], an idea was presented to decouple connections
between processes and links that they use as paths, and thus to
include source and destination socket identifiers in packets.
[RFC38] provides further detail, describing how processes might have
more than one of these paths and that more than one path may be
active at a time. As a result, there was the need to add a process
identifier to the header of each message so that incoming messages
could be demultiplexed to the appropriate process. [RFC38] further
suggested that 32 bits would be used for these identifiers. [RFC48]
discusses the current notion of listening on a specific port, but
does not discuss the issue of port determination. [RFC61] notes that
the challenge of knowing the appropriate port numbers is "left to
the processes" in general, but introduces the concept of a "well-
known" port for common services.
[RFC76] proposed a "telephone book" by which an index would allow
ports to be used by name, but still assumed that both source and
destination ports are fixed by such a system. [RFC333] proposed that
a port pair, rather than an individual port, would be used on both
sides of the connection for demultiplexing messages. This is the
final view in [RFC793] (and its predecessors, including [IEN112]),
and brings us to their current meaning. [RFC739] introduced the
notion of generic reserved ports for groups of protocols, such as
"any private RJE server" [RFC739]. Although the overall range of
such ports was (and remains) 16 bits, only the first 256 (high 8
bits cleared) in the range were considered assigned.
[RFC758] is the first to describe a list of such well-known ports,
as well as describing ranges used for different purposes:
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Binary Octal
-----------------------------------------------------------
0-63 0-77 Network Wide Standard Function
64-127 100-177 Hosts Specific Functions
128-223 200-337 Reserved for Future Use
224-255 340-377 Any Experimental Function
In [RFC820] those range meanings disappeared, and a single list of
assignments is presented. By [RFC900] the ranges appeared as decimal
numbers rather than the octal ranges used previously. [RFC1340]
increased this range from 0..255 to 0..1023, and began to list TCP
and UDP port assignments individually (although the assumption was,
and remains, that once assigned a port applies to all transport
protocols, including TCP, UDP, recently SCTP and DCCP, as well as
ISO-TP4 for a brief period in the early 1990s). [RFC1340] also
established the Registered range of 1024-59151, though it notes that
it is not controlled by the IANA at that point. The list provided by
[RFC1700] in 1994 remained the standard until it was declared
replaced by an on-line version, as of [RFC3232] in 2002.
4. Current Port Use
The current IANA website (www.iana.org) indicates three ranges of
port assignments:
Binary Hex
-----------------------------------------------------------
0-1023 0x03FF Well-Known (also System)
1024-49151 0x0400-0xBFFF Registered (also User)
49152-65535 0xC000-0xFFFF Dynamic (also Private)
Well-known encompasses the range 0..1023. On some systems, use of
these ports requires privileged access, e.g., that the process run
as 'root', which is why these are referred to as System ports. The
ports from 1024..49151 denotes non-privileged services, known as
Registered; because these ports do not run with special privileges,
they are often referred to as User ports. Dynamic (also known as
Private) ports are not assigned.
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Both Well-Known and Registered ports are assigned through IANA, so
both are sometimes called 'registered ports'. As a result, the term
'registered' is ambiguous, referring either to the entire range 0-
49151 or to the User ports. Complicating matters further, System
ports do not always require special (i.e., 'root') privilege. For
clarity, the remainder of this document refers to the port ranges as
System, User, and Dynamic.
5. What is a Port?
A port is a 16-bit number used for two distinct purposes:
o Demultiplexing transport connections within an end host
o Identifying a service
The first purpose requires that each transport connection between a
given pair of IP addresses use a different pair of ports, but does
not require either coordination or registration of port use. It is
the second purpose that drives the need for a common registry.
Consider a user wanting to run a web server. That service could run
on any port, provided that all clients knew what port to use to
access that service at that host. Such information can be
distributed out-of-band, e.g., in the URI:
http://www.example.com:51509/
Ultimately, the correlation of a service with a port number is an
agreement between just the two endpoints of the connection. A web
server can run on port 53, which might appear as DNS traffic to
others but will connect to browsers that know to use port 53 rather
than 80.
As a concept, a service is the combination of ISO Layers 5-7 that
represents an application protocol capability. For example www (port
80) is a service that uses HTTP as an application protocol and
provides access to a web server [RFC2616]. However, it is possible
to use HTTP for other purposes, such as command and control. This is
why some current service names (HTTP, e.g.) are a bit overloaded -
they describe not only the application protocol, but a particular
service.
IANA assigns ports so that Internet endpoints do not need pairwise,
explicit coordination of the meaning of their port numbers. This is
the primary reason for requesting assigned ports with IANA - to have
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a common agreement between all endpoints on the Internet as to the
meaning of a port.
Ports are sometimes used by intermediate devices on a network path,
either to monitor available services, to monitor traffic (e.g., to
indicate the data contents), or to intercept traffic (to block,
proxy, relay, aggregate, or otherwise process it). In each case, the
intermediate device interprets traffic based on the port number. It
is important to recognize that any interpretation of ports - except
at the endpoints - may be incorrect, because ports are meaningful
only at the endpoints. Further, ports may not be visible to these
intermediate devices, such as when the transport protocol is
encrypted (as in network- or link-layer tunnels), or when a packet
is fragmented (in which case only the first fragment has the port
information). Such port invisibility may interfere with these in-
network port-based capabilities.
Ports can also be useful for other purposes. Assigned ports can
simplify end system configuration, so that individual installations
do not need to coordinate their use of arbitrary ports. Such
assignments can also simplify firewall management, so that a single,
fixed firewall configuration can either permit or deny a service.
6. Conservation
Assigned ports are a scarce resource that is globally shared by the
entire Internet community. As a result, every attempt should be made
to conserve ports and request assignments only for those that are
absolutely necessary.
There are a variety of ways that systems can conserve port numbers:
o A single assigned port number can support different functions
over separate connections, determined using in-band
information. FTP data connection can transfer binary or text
files, the latter translating line-terminators, as indicated
in-band over the control port [RFC959].
o A single assigned port can indicate the Dynamic port(s) on
which different capabilities are supported, as with passive-
mode FTP [RFC959].
o Several existing services can indicate the Dynamic port(s) on
which other services are supported, such as with mDNS and
portmapper [RFC1833] [RFC6762] [RFC6763].
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o Copies of an existing service can be differentiated by using
different IP addresses, either on different hosts or as
different real or virtual interfaces (or even operating
systems) on the same host.
o Copies of some existing services can be differentiated using
in-band information (e.g., URIs in HTTP Host field and TLS
Server Name Indication extension) [RFC2616] [RFC3546].
o Different performance requirements can already be supported
using separate connections or endpoints with different
capabilities or configurations.
Port numbers are intended to differentiate services, not
performance, replicas, connections, or payload types. Port numbers
are also a very small space, so it is never appropriate to consume
port numbers to save larger spaces, such as IP addresses.
Others have noted "think twice about modifying TCP, then don't"
[RFC1263]. In this case, similar advice might be:
o Think twice before asking for an assigned port, then try not
to.
o If more than one port is desired, consider revising the
architecture until only one is needed, or, preferably, none.
6.1. Firewall and NAT Considerations
Assigned ports are useful for configuring firewalls and other port-
based systems for access control. Ultimately, these ports indicate
services only to the endpoints, and any intermediate device that
assigns meaning to a value can be incorrect. End systems might agree
to run web services (HTTP) over port 53 (typically used for DNS)
rather than port 80, at which point a firewall that blocks port 80
but permits port 53 would not have the desired effect. However,
assigned ports often are important in helping configure firewalls.
Using Dynamic ports, or explicitly-indicated ports indicated in-band
over another service (such as with FTP) often complicates firewall
and NAT interactions [RFC959]. FTP over firewalls often requires
direct support for deep-packet inspection (to snoop for the Dynamic
port for the NAT to correctly map) or passive-mode FTP (in which
both connections are opened from the client side).
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7. How to Use Assigned Ports
Ports are assigned by IANA by a set of documented procedures [RFC
6335]. The following section describes the steps users can take to
help assist with the use of assigned ports, and with preparing an
application for a port assignment.
7.1. Is a port assignment necessary?
First, it is useful to consider whether a port assignment is
required. In many cases, a new assignment may not be needed, for
example:
o Is this really a new service, or can an existing service
suffice?
o Is this an experimental service [RFC3692]? If so, consider
using the current experimental ports [RFC2780].
o Is this service independently useful? Some systems are
composed from collections of different service capabilities,
but not all component functions are useful as independent
services. Ports are typically shared among the smallest
independently-useful set of functions. Different service uses
or properties can be supported in separate connections after
an initial negotiation, e.g., to support software
decomposition.
o Can this service use a Dynamic port that is coordinated out-
of-band, e.g.:
o By explicit configuration of both endpoints.
o By shared information within the same host (e.g., a
configuration file or indicated within a URI).
o Using information exchanged on a related service: FTP, SIP,
etc. [RFC959] [RFC2543].
o Using an existing port discovery service: portmapper, mDNS,
etc. [RFC1833] [RFC6762] [RFC6763].
There are a few good examples of reasons that more directly suggest
that not only is a port not necessary, but it is directly counter-
indicated:
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o Ports are not for performance. Performance enhancement can
occur within separate connections.
o Additional ports are not to replicate an existing service. For
example, a device is configured using a typical web browser
then it is a copy of HTTP port 80 and does not warrant a new
assignment. However, an automated system that happens to use
HTTP framing - but cannot be accessed by a browser - might be
a new service. A good way to tell is "can an unmodified client
of the existing service interact with the proposed service"?
If so, that service would be a copy of an existing service and
does not merit a new assignment.
o Separate ports are not for insecure versions of existing (or
new) secure services. Consider that a service that includes
required security would be made vulnerable by having the same
capability accessible without security.
Note that the converse is different, i.e., it can be useful to
create a new, secure service that replicates an existing
insecure service on a new port assignment. This can be
necessary when the existing service is not backward-compatible
with security enhancements, such as the use of TLS or SSL
[Hi95] [RFC5246].
New services should support security or should consider
optional security. A new service should not need a port for an
insecure version; at best, this would be a performance issue
(see the first bullet), and at worst this presents a new
vulnerability.
o Ports are not for indicating different service versions.
Version differentiation should be handled in-band, e.g., using
a version number at the beginning of a connection or
transaction. This may not be possible with legacy assignments,
but all new assignments should incorporate support for version
indication.
Some users may not need assigned port numbers at all, e.g., SIP
allows voice calls to use Dynamic ports [RFC2543]. Some systems can
register services in the DNS, using SRV entries. These services can
be discovered by a variety of means, including mDNS, or via direct
query [RFC6762] [RFC6763]. In such cases, users can more easily
request a SRV name, which are assigned first-come, first-served from
a much larger namespace.
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IANA assigns port numbers, but this assignment is typically used
only for servers, i.e., the host that listens for incoming
connections. Clients, i.e., hosts that initiate connections,
typically refer to those assigned ports but do not need port
assignments for their endpoint.
7.2. How Many Ports?
As noted earlier, systems might require a single port assignment,
but rarely require multiple ports. There are a variety of known ways
to reduce port use. Although some may be cumbersome or inefficient,
they are always preferable to consuming additional ports.
Such techniques include:
o Use of a discovery service, either a shared service (mDNS), or
a discovery service for a given system [RFC6762] [RFC6763].
o Multiplex packet types using in-band information, either on a
per-message or per-connection basis. Such demultiplexing can
even hand-off different connections and types of connections
among different processes, such as is done with FTP [RFC959].
There are some cases where it is still important to have assigned
port numbers, largely to traverse either NATs or firewalls. Although
automatic configuration protocols have been proposed and developed,
system designers cannot yet rely on their presence.
In the past, some services were assigned multiple ports or sometimes
fairly large port ranges (e.g., X11). This occurred for a variety of
reasons: port conservation was not widely understood, assignments
were not as ardently reviewed, etc. This no longer reflects current
practice and such assignments are not considered to constitute a
precedent for future assignments.
7.3. Picking a Port Number
Given a demonstrated need for a port number assignment, the next
question is how to pick the desired port number. An application for
a port assignment does not need to include a desired port number; in
that case, IANA will select from those currently available.
Users should consider whether the requested port number is
important. For example, would an assignment be acceptable if IANA
picked the port number value? Would a TCP port number assignment be
needed useful if the corresponding UDP one were unavailable
(assuming the proposed service needed only a TCP port)?
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The most critical issue in picking a number is selecting the desired
range, i.e., System vs. User ports. The distinction was intended to
indicate a difference in privilege; originally, System ports
required privileged ('root') access, while User ports did not. That
distinction has since blurred because some current systems do not
limit access control to System ports and because some System
services have been replicated on User numbers (e.g., IRC). Even so,
System port assignments have continued at an average rate of 3-4 per
year over the past 7 years (2007-2013), indicating that the desire
to keep this distinction continues.
As a result, the difference between System and User ports needs to
be treated with caution. Developers are advised to treat services as
if they are always run without privilege. As a result:
>> Developers SHOULD NOT apply for System ports because the
increased privilege they provide is not always enforced.
Even when developers seek a System port, it may be very difficult to
obtain. System port assignment requires IETF Review or IESG Approval
and justification that both User and Dynamic port ranges are
insufficient [RFC6335].
>> System implementers SHOULD enforce the need for privilege for
processes to listen on System ports.
At some future date, it might be useful to deprecate the distinction
between System and User ports altogether. Services typically require
elevated ('root') privileges to bind to a System port, but many such
services go to great lengths to immediately drop those privileges
just after connection establishment to reduce the impact of an
attack using their capabilities. Such services might be more
securely operated on User ports than on System ports. Further, if
System ports were no longer assigned, it would cost only 180 of the
1024 system values (17%), or 180 of the overall 49152 assigned
values (<0.04%).
7.4. Support for Security
Just as a service is a way to obtain information or processing from
a host over a network, an service can also be the opening through
which to attack that host. Given the current state of cybersecurity
in the Internet, the following advice is prudent:
>> New services SHOULD support security, either directly or via a
secure transport such as TLS [RFC5246].
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>> Insecure versions of new secure services SHOULD be avoided
because of the new vulnerability they create.
>> Security SHOULD NOT rely on port number distinctions alone; every
service, whether secure or not, SHOULD expect to be attacked.
There is debate as to how to secure legacy insecure services
[RFC6335]. Some argue that secure variants should share the existing
port assignment, such that security is enabled on a per-connection
basis [RFC2817]. Others argue that security should be supported on a
new port assignment and be enabled by default. IANA currently
permits either approach, although use of a single port is consistent
with port conservation. A separate port might be important for
security coordination (e.g., firewall management), but this might
further argue for deprecation of the insecure variant.
Optional security can penalize performance, requiring additional
round-trip exchanges before a connection can be established. As
discussed earlier, ports are a critical resource and it is
inappropriate to consume assignments to increase performance.
Note however that a new service might not be eligible for IANA
assignment of both an insecure and a secure variant of the same
service, and similarly IANA might be skeptical of an assignment for
an insecure port for a secure service. In both cases, security of
the service is compromised by adding the insecure port assignment.
7.5. Support for Future Versions
Current IANA assignments are expected to support the multiple
versions on the same assigned port [RFC6335]. Versions are typically
indicated in-band, either at the beginning of a connection or
association, or in each protocol message.
>> Version support SHOULD be included in new services.
>> Version numbers SHOULD NOT be included in either the service name
or service description.
Again, the port number space is far too limited to be used as an
indicator of protocol version or message type. Although this has
happened in the past (e.g., for NFS), it should be avoided in new
requests.
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7.6. Transport Protocols
IANA assigns port numbers specific to one or more transport
protocols, typically UDP and TCP, but also SCTP, DCCP, and any other
standard transport protocol [RFC768] [RFC793] [RFC4340] [RFC4960].
Originally, IANA port assignments were concurrent for both UDP and
TCP; other transports were not indicated. However, to conserve space
and to reflect increasing use of other transports, assignments are
now specific only to the transport being used.
In general, a service should request assignments for multiple
transports using the same service name and description on the same
port number only when they all reflect essentially the same service.
Good examples of such use are DNS and NFS, where the difference
between the UDP and TCP services are specific to supporting each
transport. E.g., the UDP variant of a service might add sequence
numbers and the TCP variant of the same service might add in-band
message delimiters.
>> Service names and descriptions for multiple transport port
assignments SHOULD match only when they describe the same service,
excepting only enhancements for each supported transport.
When the services differ, their service names and descriptions
should reflect that difference. E.g., if TCP is used for the basic
control protocol and UDP for an alarm protocol, then the services
might be "name-ctl" and "name-alarm". A common example is when TCP
is used for a service and UDP is used to determine whether that
service is active (e.g., via a unicast, broadcast, or multicast test
message) [RFC1122]. The following convention has been used by IANA
for several years to indicate this case:
>> When UDP is used for discovery of an active TCP service, the UDP
service name SHOULD end in "-disc".
Some services are used for discovery, either in conjunction with a
TCP service or as a stand-alone capability. Such services will be
more reliable when using multicast rather than broadcast (over IPv4)
because IP routers do not forward "all nodes" (all 1's, i.e.,
255.255.255.255 for IPv4) broadcasts and have not been required to
support subnet-directed broadcasts since 1999 [RFC1812] [RFC2644].
This issue is relevant only for IPv4 because IPv6 does not support
broadcast.
>> UDP over IPv4 multi-host services SHOULD use multicast rather
than broadcast.
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Designers should be very careful in creating services over
transports that do not support congestion control or error recovery,
notably UDP. There are several issues that should be considered in
such cases, each summarized from [RFC5405]:
>> UDP services SHOULD be rate limited so that they use only nominal
network capacity. Users should keep in mind that "nominal" may vary
depending on the deployment environment and may be very low.
>> UDP services that use multipoint communication SHOULD be
scalable, and SHOULD NOT rely solely on the efficiency of multicast
transmission for scalability.
>> UDP services SHOULD include congestion detection and back-off.
>> UDP SHOULD NOT be used as a performance enhancement over TCP,
i.e., to circumnavigate TCP's congestion control.
7.7. When to Request an Assignment
Assignments are typically requested when a user has enough
information to reasonably answer the questions in the IANA
application. IANA applications typically take up to a few weeks to
process, with some complex cases taking up to a month. The process
typically involves a few exchanges between the IANA Ports Expert
Review team and the applicant.
An application needs to include a description of the service, as
well as to address key questions designed to help IANA determine
whether the assignment is justified.
Services that are independently developed can be requested at any
time, but are typically best requested in the last stages of design
and initial experimentation, before any deployment has occurred that
cannot easily be updated.
>> Users MUST NOT deploy implementations that use assigned ports
prior their assignment by IANA.
>> Users MUST NOT deploy implementations that default to using the
experimental System ports (1021 and 1022 [RFC4727]) outside a
controlled environment where they can be updated with a subsequent
assigned port [RFC3692].
Deployments that use ports before deployment complicate IANA
management of the port space. Keep in mind that this recommendation
protects existing assignees, users of current services, and
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applicants for new assignments; it helps ensure that a desired
number and service name are available when assigned. The list of
currently unassigned numbers is just that - *currently* unassigned.
It does not reflect pending applications. Waiting for an official
IANA assignment reduces the chance that an assignment request will
conflict with another deployed service.
Applications made through Internet Draft / RFC publication typically
use a placeholder ("PORTNUM") in the text, and use an experimental
port number until a final assignment has been made [RFC6335]. That
assignment is initially indicated in the IANA Considerations section
of the document, and is tracked by the RFC Editor. When the RFC
reaches the last stages of publication, that request is forwarded to
IANA for handling. At that time, IANA typically requests that the
applicant fill out the application form on their website, because
not every protocol document addresses the information required.
"Early" assignments can be made when justified, e.g., for early
interoperability testing, according to existing process [RFC4020]
[RFC6335].
Using this single application process also ensures that IANA has
complete information even if the RFC publication is interrupted. For
this reason as well, the application should be complete and not
refer solely to the Internet Draft, RFC, a website, or any other
external documentation.
>> Users writing specifications SHOULD use symbolic names for port
numbers and service names until an IANA assignment has been
completed.
7.8. Squatting
"Squatting" describes the use of a number from the assigned range in
deployed software without IANA assignment. It is hazardous because
IANA cannot track such usage and thus cannot avoid making legitimate
assignments that conflict with such unauthorized usage.
Note that there are numerous services that have squatted on such
numbers that are in widespread use. Even such widespread de-facto
use may not justify a later IANA assignment of that value,
especially if either the value has already been assigned to a
legitimate applicant or if the service would not qualify for an
assignment of its own accord.
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7.9. Other Considerations
As noted earlier, System ports should be used sparingly, and it is
better to avoid them altogether. This avoids the potentially
incorrect assumption that the service on such ports run in a
privileged mode.
Port names and numbers are not intended to be changed. Once
deployed, it can be very difficult to recall every implementation,
so the assignment should be retained. However, in cases where the
current assignee of a name or number has reasonable knowledge of the
impact on such uses, and is willing to accept that impact, the name
or number of an assignment can be changed [RFC6335]
Aliases, or multiple service names for the same port number, are no
longer considered appropriate [RFC6335].
8. Security Considerations
This document discusses ways to conserve port numbers, notably
through encouraging demultiplexing within a single port. As such,
there may be cases where two variants of a protocol - insecure and
secure (such as using optional TLS) or different versions - are
suggested to share the same port.
This document reminds protocol designers that port numbers are not a
substitute for security, and should not alone be used to avoid
denial of service or firewall traffic, notably because their use is
not regulated or validated.
9. IANA Considerations
The entirety of this document focuses on IANA issues, notably
suggestions that help ensure the conservation of port numbers and
provide useful hints for issuing informative requests thereof.
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2780] Bradner, S., and V. Paxson, "IANA Allocation Guidelines
For Values In the Internet Protocol and Related Headers",
BCP 37, RFC 2780, March 2000.
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[RFC3692] Narten, T., "Assigning Experimental and Testing Numbers
Considered Useful", BCP 82, RFC 3962, Jan. 2004.
[RFC4727] Fenner, B., "Experimental Values in IPv4, IPv6, ICMPv4,
ICMPv6, UDP, and TCP Headers", RFC 4727, November 2006.
[RFC5405] Eggert, L., and G. Fairhurst, "Unicast UDP Usage
Guidelines for Application Designers", BCP 145, RFC 5405,
Nov. 2008.
[RFC6335] Cotton, M., L. Eggert, J. Touch, M. Westerlund, and S.
Cheshire, "Internet Assigned Numbers Authority (IANA)
Procedures for the Management of the Service Name and
Transport Protocol Port Number Registry", BCP 165, RFC
6335, August 2011.
10.2. Informative References
[Hi95] Hickman, K., "The SSL Protocol", February 1995.
[IEN112] Postel, J., "Transmission Control Protocol", IEN 112,
August 1979.
[RFC33] Crocker, S., "New Host-Host Protocol", RFC 33 February
1970.
[RFC37] Crocker, S., "Network Meeting Epilogue", RFC 37, March
1970.
[RFC38] Wolfe, S., "Comments on Network Protocol from NWG/RFC
#36", RFC 38, March 1970.
[RFC48] Postel, J., and S. Crocker, "Possible protocol plateau",
RFC 48, April 1970.
[RFC61] Walden, D., "Note on Interprocess Communication in a
Resource Sharing Computer Network", RFC 61, July 1970.
[RFC76] Bouknight, J., J. Madden, and G. Grossman, "Connection by
name: User oriented protocol", RFC 76, October 1970.
[RFC333] Bressler, R., D. Murphy, and D. Walden. "Proposed
experiment with a Message Switching Protocol", RFC 333,
May 1972.
[RFC739] Postel, J., "Assigned numbers", RFC 739, November 1977.
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[RFC758] Postel, J., "Assigned numbers", RFC 758, August 1979.
[RFC768] Postel, J., "User Datagram Protocol", RFC 768, August
1980.
[RFC793] Postel, J., "Transmission Control Protocol" RFC 793,
September 1981
[RFC820] Postel, J., "Assigned numbers", RFC 820, August 1982.
[RFC900] Reynolds, J., and J. Postel, "Assigned numbers", RFC 900,
June 1984.
[RFC959] Postel, J., and J. Reynolds, "FILE TRANSFER PROTOCOL
(FTP)", RFC 959, October 1985.
[RFC1122] Braden, B. (Ed.), "Requirements for Internet Hosts --
Communication Layers", RFC 1122, October 1989.
[RFC1263] O'Malley, S., and L. Peterson, "TCP Extensions Considered
Harmful", RFC 1263, October 1991.
[RFC1340] Reynolds, J., and J. Postel, "Assigned numbers", RFC 1340,
July 1992.
[RFC1700] Reynolds, J., and J. Postel, "Assigned numbers", RFC 1700,
October 1994.
[RFC1812] Baker, F. (Ed.), "Requirements for IP Version 4 Routers",
RFC 1812, June 1995.
[RFC1833] Srinivasan, R., "Binding Protocols for ONC RPC Version 2",
RFC 1833, August 1995.
[RFC2543] Handley, M., H. Schulzrinne, E. Schooler, and J.
Rosenberg, "SIP: Session Initiation Protocol", RFC 2543,
March 1999.
[RFC2616] Fielding, R., J. Gettys, J. Mogul, H. Frystyk, L.
Masinter, P. Leach, and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC2644] Senie, D., "Changing the Default for Directed Broadcasts
in Routers", RFC 2644, August 1999.
[RFC2817] Khare, R., and S. Lawrence, "Upgrading to TLS Within
HTTP/1.1", RFC 2817, May 2000.
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[RFC3232] Reynolds, J. (Ed.), "Assigned Numbers: RFC 1700 is
Replaced by an On-line Database", RFC 3232, January 2002.
[RFC3546] Blake-Wilson, S., D. Hopwood, and T. Wright, "Transport
Layer Security (TLS) Extensions", RFC 3546, June 2003.
[RFC4020] Kompella, K. and A. Zinin, "Early IANA Allocation of
Standards Track Code Points", BCP 100, RFC 4020, February
2005.
[RFC4340] Kohler, E., M. Handley, and S. Floyd, "Datagram Congestion
Control Protocol (DCCP)", RFC 4340, March 2006.
[RFC4960] Stewart, R. (Ed.), "Stream Control Transmission Protocol",
RFC 4960, September 2007.
[RFC5246] Dierks, T., and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC6762] Cheshire, S., and M. Krochmal, "Multicast DNS", RFC 6762,
February 2013.
[RFC6763] Cheshire, S., and M. Krochmal, "DNS-Based Service
Discovery", RFC 6763, February 2013.
11. Acknowledgments
This work benefitted from the feedback from Lars Eggert, Gorry
Fairhurst, and Eliot Lear, as well as discussions of the IETF TSVWG
WG.
This document was prepared using 2-Word-v2.0.template.dot.
Authors' Addresses
Joe Touch
USC/ISI
4676 Admiralty Way
Marina del Rey, CA 90292-6695
U.S.A.
Phone: +1 (310) 448-9151
EMail: touch@isi.edu
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