Internet Assigned
Numbers Authority (IANA) Procedures for the Management of the Transport
Protocol Port Number and Service Name Registry
Internet Corporation for Assigned Names and
Numbers
4676 Admiralty Way, Suite 330
90292
Marina del Rey
CA
USA
+1 310 823 9358
michelle.cotton@icann.org
http://www.iana.org/
Nokia Research Center
P.O. Box 407
00045
Nokia Group
Finland
+358 50 48 24461
lars.eggert@nokia.com
http://research.nokia.com/people/lars_eggert/
Johns Hopkins
University
+1 301 728 7199
mankin@psg.com
http://www.psg.com/~mankin/
USC/ISI
4676 Admiralty Way
90292
Marina del Rey
CA
USA
+1 310 448 9151
touch@isi.edu
http://www.isi.edu/touch
Ericsson
Torshamsgatan 23
Stockholm
164 80
Sweden
+46 8 719 0000
magnus.westerlund@ericsson.com
Transport Area
Transport Area Working Group
IANA
transport
ports
port numbers
allocation
procedures
This document defines the procedures that the Internet Assigned
Numbers Authority (IANA) uses when handling registration and other
requests related to the transport protocol port number and service name
registry. It also discusses the rationale and principles behind these
procedures and how they facilitate the long-term sustainability of the
registry.
This document updates RFC2780 by obsoleting Sections 8 and 9.1 of
that RFC, it updates the IANA allocation procedures for DCCP as
defined in RFC4340, and it updates RFC2782 to clarify what a service name
is and how it is registered.
For many years, the allocation and registration of new port number
values and service names for use with the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) have had less than
clear guidelines. New transport protocols have been added - the Stream Control Transmission
Protocol (SCTP) and the Datagram
Congestion Control Protocol (DCCP) - and new mechanisms have been developed (DNS SRV records ), each
with separate registries and separate guidelines. The community
recognized the need for additional procedures beyond just assignment;
notably modification, revocation, and release.
A key factor of this procedural streamlining is to establish
identical registration procedures for all IETF transport protocols.
This document brings the IANA procedures for TCP and UDP in line with
those already for SCTP and DCCP, resulting in a single
process that requesters and IANA follow for all requests for all
transport protocols, including those not yet defined.
In addition to detailing the IANA procedures for the initial
assignment of port numbers and service names, this document also
specifies post-assignment procedures that until now have been handled
in an ad hoc manner. These include procedures to de-register a port
number that is no longer in use, to re-use a port number allocated
for one application that is no longer in use for another application,
and procedure by which IANA can unilaterally revoke a prior port
number registration. discusses the specifics of these
procedures and processes that requesters and IANA follow for all requests for all current and future
transport protocols.
It is
important to note that ownership of registered port numbers and service
names remains with IANA. For protocols developed by IETF working groups, IANA now also offers a method
for the "early" assignment of port numbers and service names , as described in .
This document updates IANA's allocation guidelines for UDP
and TCP port numbers by obsoleting Sections 8 and 9.1 of .
(Note that different sections of were updated in February 2008 by .)
This document also updates the IANA allocation procedures for DCCP as
defined in . It updates to clarify what a service name is and how it is registered, because simply refers to when defining service names, which in turn contains now-obsolete copies of various IANA registries .
Information about the registration procedures for the
port registry has existed in three locations: the forms for requesting port
number registrations on the IANA web site , an introductory text section in the file
listing the port number registrations themselves , and two brief sections of the IANA Allocation
Guidelines .
Similarly, the procedures surrounding service names have been
historically unclear. Service names were originally created as mnemonic
identifiers for port numbers without a well-defined syntax, beyond the
14-character limit mentioned on the IANA website . Even that
length limit has not been consistently applied, and some assigned
service names are 15 characters long. When service identification via
DNS SRV RRs were introduced, the ambiguities in the syntactic definition
of the service namespace, together with a requirement by IANA to only
assign service names and port numbers in combination, led to the
creation of an ad hoc service name registry outside of the control of
IANA .
It has also been historically unclear if the "name" entries registered in the "Protocol and Service Names Registry" can be used as service names. defines the
names in that registry as either service names or protocol names. It is
likely that these names has been interpreted as being valid service
names and consequently have been used, e.g., in SRV records. This motivates why this document merges the 166 protocol and service names defined in that registry into the port number registry .
This document aggregates all this scattered information into a single
reference that aligns and clearly defines the management procedures for
both port numbers and service names. It gives more detailed guidance to
prospective requesters of ports and service names than the existing
documentation, and it streamlines the IANA procedures for the management
of the registry, so that management requests can complete in a timely
manner.
This document defines rules for registration of service names without associated port numbers,
for such usages as DNS SRV records, which was not possible under the previous IANA procedures. These new procedures
also merge service name registrations from the non-IANA "ad
hoc" registry and from the the IANA "Protocol and Service Names" registry
into the IANA "Port and Service Name" registry , which from here on is the single authoritative registry for service names and port numbers.
An additional purpose of this document is to describe the principles that
guide the IETF and IANA in their role as the long-term joint stewards of
the port number registry. TCP and UDP have been a remarkable success
over the last decades. Thousands of applications and application-level
protocols have registered ports and service names for their use, and
there is every reason to believe that this trend will continue into the
future. It is hence extremely important that management of the registry
follow principles that ensure its long-term usefulness as a shared
resource. discusses these principles
in detail.
The Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) have enjoyed a remarkable success over the
decades as the two most widely used transport protocols on the Internet.
They have relied on the concept of "ports" as logical entities for
Internet communication. Ports serve two purposes: first, they provide a
demultiplexing identifier to differentiate transport sessions between
the same pair of endpoints, and second, they may also identify the
application protocol and associated service to which processes bind.
Newer transport protocols, such as the Stream Control Transmission
Protocol (SCTP) and the Datagram
Congestion Control Protocol (DCCP) have
adopted the concept of ports for their communication sessions and use
16-bit port numbers in the same way as TCP and UDP (and UDP-Lite , a variant of UDP).
Port numbers are the original and most widely used means for
application and service identification on the Internet. Ports are 16-bit
numbers, and the combination of source and destination port numbers
together with the IP addresses of the communicating end systems uniquely
identifies a session of a given transport protocol. Port numbers are
also known by their corresponding service names such as "telnet" for
port number 23 and both "http" and "www" for port number 80.
Hosts running services, hosts accessing services on other hosts, and
intermediate devices (such as firewalls and NATs) that restrict services
need to agree on which service corresponds to a particular destination
port. Although this is ultimately a local decision with meaning only between the endpoints of a
connection, most Internet components use a single, shared view of this
association, provided by the Internet Assigned Numbers Authority (IANA)
through the port number registry .
Over time, the assumption that a particular
port number necessarily implies a particular service may become less
true. For example, multiple instances of the same service can run on different ports on the same host, or NATs that support port mapping or registration need to offer service instances using the same port on several internal hosts available to the public Internet on different ports. This document assumes, however, that ports are most often used in a conventional manner - where endpoints and intermediate devices all share
the common view of the IANA port number registry.
Applications either use numeric port numbers directly, look up port
numbers based on service names via system calls such as getservbyname()
on UNIX, look up port numbers by performing queries for DNS SRV records
or determine port numbers in a
variety of other ways .
Designers of applications and application-level protocols may apply
to IANA for an assigned port number and service name for a specific
application, and may - after successful registration - assume that no
other application will use that port number and service name for its
communication sessions. Alternatively, application designers may also
only ask for an assigned service name, if their application does not
require a fixed port number. The latter alternative is encouraged when
possible, in order to conserve the more limited port number space.
This includes, for example, applications that use DNS SRV records to look up port numbers at runtime, or transports that use service names
not coupled to port numbers, e.g., TCP portnames .
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 BCP 14, RFC 2119 .
Service names are the unique key in the Port and Service Name
registry. This unique symbolic name for a service may also be used for other
purposes, such as DNS SRV records. Within the registry, this unique key ensures that different
services can be unambiguously distinguished, thus preventing name collisions and avoiding confusion about who is the registration owner of a particular entry.
For each service name, there may exist zero or more associated port number assignments. A port number assignment associated with a service name contains the transport protocol, port number and possibly additional data, such as a DCCP service code. There
may be more than one service name associated with a particular transport
protocol and port. This SHOULD only occur when all such service names
are aliases for the same service, such as with "www" and "http".
Service names are assigned on a "first come, first served"
basis, as described in .
Names should be brief and informative, avoiding words or
abbreviations that are redundant in the context of the registry (e.g., "port", "service", "protocol", etc.) Names referring to discovery services, e.g., using
multicast or broadcast to identify endpoints capable of a given service,
SHOULD use an easily identifiable suffix (e.g., "-disc").
defines SRV records for the DNS system. One part of the
DNS name of an SRV record includes what is called "SERVICE", i.e., a
symbolic name for the service. This document updates in order to
clarify that the symbolic name ("SERVICE") SHALL only be a service name as
defined in this document that has been registered with IANA and recorded in the port number and service name registry . This to ensure that only a single registry
exist and name collisions can be more easily avoided in the future.
TCP, UDP (and UDP-Lite), SCTP and DCCP use 16-bit namespaces for
their port number registries. The port registries for all these
transport protocols are subdivided into three ranges of numbers, and
describes the IANA procedures for each
range in detail:
the Well Known Ports, also known as the System Ports, from 0-1023
(assigned by IANA)
the Registered Ports, also known as the User Ports, from
1024-49151 (assigned by IANA)
the Dynamic Ports, also known as the Private Ports, from
49152-65535 (never assigned)
Of the assignable port ranges (Well Known and Registered, i.e., port
numbers 0-49151), individual port numbers are in one of three states at
any given time:
Assigned: Assigned port numbers are currently allocated to the
service indicated in the registry.
Unassigned: Unassigned port numbers are currently available for
assignment upon request, as per the procedures outlined in this
document.
Reserved: Reserved port numbers are not available for regular
assignment; they are "assigned to IANA" for special purposes.
Reserved port numbers include values at the edges of each range,
e.g., 0, 1023, 1024, etc., which may be used to extend these ranges
or the overall port number space in the future.
In order to keep the size of the registry manageable, IANA typically
only records the Assigned and Reserved port numbers and service names in
the registry. Unassigned values are typically not explicitly listed.
As a data point, when this document was written, approximately 76% of
the TCP and UDP Well Known Ports were assigned, and approximately 9% of the Registered Ports were assigned. (As noted, Dynamic Ports are never
assigned.)
Of the Well Known ports, two TCP and UDP port numbers (1021 and
1022), together with their respective service names ("exp1" and
"exp2"), have been assigned for experimentation with new applications
and application-layer protocols that require a port number in the
assigned ports ranges .
Please refer to Sections 1 and 1.1 of "Assigning Experimental and
Testing Numbers Considered Useful" for
how these experimental port numbers are to be used.
This document
registers the same two port numbers and service names for
experimentation with new application-layer protocols over SCTP and
DCCP in .
Unfortunately, it can be difficult to limit access to these ports.
Users SHOULD take measures to ensure that experimental ports are
connecting to the intended process. For example, users of these
experimental ports might include a 64-bit nonce, once on each segment
of a message-oriented channel (e.g., UDP), or once at the beginning of
a byte-stream (e.g., TCP), which is used to confirm that the port is
being used as intended. Such confirmation of intended use is
especially important when these ports are associated with privileged
(e.g., system or administrator) processes.
Management procedures for the port number and service name registry
include allocation of port numbers and service names upon request, as
well as coordination of information about existing allocations. The
latter includes maintaining contact and description information about
assignments, revoking abandoned assignments, and redefining assignments
when needed.
Of these procedures, port number allocation
is most critical, in order to continue to conserve the remaining port
numbers.
As noted earlier, only ~9% of the Registered Port space is
currently assigned. The current rate of assignment is approximately 400 ports/year,
and has remained linear for the past 8 years. At that rate, if
similar conservation continues, this resource will sustain another 85
years of assignment - without the need to resort to reassignment of released values or revocation.
Note that the namespace available for service names is even larger,
which allows for a simpler management procedures.
Before the publication of this document, the principles of port
number and service name management followed a few mostly
undocumented guidelines. They are recorded here for historical
purposes, and this document updates them in . These principles were:
TCP and UDP ports were simultaneously allocated when either was
requested
Port numbers were the primary allocation; service names were
informative only, and did not have a well-defined syntax
Port numbers were conserved informally, and sometimes
inconsistently (e.g., some services were allocated ranges of many
port numbers even where not strictly necessary)
SCTP and DCCP port number and service name registries were
managed separately from the TCP/UDP registries
Service names could not be assigned in the ports registry without
assigning a corresponding port number at the same time
This document attempts to document, clarify and align these
guidelines in order to more conservatively manage the limited remaining
port number space and to enable and promote the use of service names for
service identification without associated port numbers, where
possible.
This section summarizes the basic principles by which IANA attempts
to conserve the port number space. This description is intended to
inform applicants requesting port numbers. IANA decisions are not
required to be bound to these principles, however; other factors may
come into play, and exceptions may occur where deemed in the best
interest of the Internet.
The basic principle of port number registry management is to
conserve use of the port space where possible. Extensions to support
larger port number spaces would require changing many core protocols
of the current Internet in a way that would not be backward compatible
and interfere with both current and legacy applications.
Conservation of the port number space recognizes that because this
space is a limited resource, applications are expected to participate
in the traffic demultiplexing process where feasible. The port numbers
are expected to encode as little information as possible that will
still enable an application to perform further demultiplexing by
itself. In particular:
IANA will allocate only one assigned port number per service or application
IANA will allocate only one assigned port number for all versions of a service
(e.g., running the service with or without a security
mechanism, or for updated variants of a service)
IANA will allocate only one assigned port number for all different types of
devices using or participating in the same service
IANA will allocate port numbers only for the transport protocols
explicitly named in an registration request
IANA may recover unused port numbers, via the new procedures of
de-registration, revocation, and transfer
IANA may begin assigning service names that do not request a
corresponding port number allocation under a simple "First Come,
First Served" policy (assignments
involving port numbers still require "Expert Review")
A given service is expected to further demultiplex messages
where possible. For example, applications and protocols are expected
to include in-band version information, so that future versions of the
application or protocol can share the same allocated port.
Applications and protocols are also expected to be able to efficiently
use a single allocated port for multiple sessions, either by
demultiplexing multiple streams within one port, or using the
allocated port to coordinate using dynamic ports for subsequent
exchanges (e.g., in the spirit of FTP ).
Ports are used in various ways,
notably:
as endpoint process identifiers
as application protocol identifiers
for firewall filtering purposes
The process and protocol identifier use suggests that
anything a single process can demultiplex, or that can be encoded into
a single protocol, should be. The firewall filtering use suggests that
some uses that could be de-multiplexed or encoded must be separated to
allow for firewall management. Note that this latter use is much less
sound, because port numbers have meaning only for the two endpoints
involved in a connection, and drawing conclusions about the service
that generated a given flow based on observed port numbers is
inherently problematic.
Further, previous separation of protocol variants
based on security capabilities (e.g., HTTP on port 80 vs. HTTPS on port 443) is not recommended for new protocols, because all should be security-capable and capable of negotiating the use of security in-band.
IANA will begin assigning protocol numbers only for those transport
protocols explicitly included in a registration request. This ends the
long-standing practice of automatically assigning a port number to an
application for both TCP and a UDP, even if the request is only for
one of these transport protocols. The new allocation procedure
conserves resources by only allocating a port number to an application
for those transport protocols (TCP, UDP, SCTP and/or DCCP) it actually
uses. The port number will be marked as Reserved - instead of Assigned
- in the port number registries of the other transport protocols. When
applications start supporting the use of some of those additional
transport protocols, their implementors MUST request IANA to convert
the reservation into an assignment. An application MUST NOT assume
that it can use a port number assigned to it for use with one
transport protocol with another transport protocol without asking IANA
to convert the reservation into an assignment.
Conservation of port numbers is improved by procedures that allow
previously allocated port numbers to become Unassigned, either through
de-registration or through revocation, and by a procedure that lets
application designers transfer an allocated but unused port number to
a new application. describes
these procedures, which so far were undocumented. Port number
conservation is also improved by recommending that applications that
do not require an allocated port, e.g., because they can use
service-name-based lookups, chose this option and only register a
service name.
describes the different port number
ranges. It is important to note that IANA applies slightly different
procedures when managing the different ranges of the port number
registry:
Ports in the Dynamic Ports range (49152-65535) have been
specifically set aside for local and dynamic use and cannot be
registered through IANA. Applications may simply use them for
communication without any sort of registration. On the other hand,
applications MUST NOT assume that a specific port number in the
Dynamic Ports range will always be available for communication at
all times, and a port number in that range hence MUST NOT be used
as a service identifier.
Ports in the Registered Ports range (1024-49151) are available
for registration through IANA, and MAY be used as service
identifiers upon successful registration. Because registering a
port number for a specific application consumes a fraction of the
shared resource that is the port number registry, IANA will
require the requester to document the intended use of the port
number. This documentation will be input to the "Expert Review"
allocation procedure , by which IANA
will have a technical expert review the request to determine
whether to grant the registration. The submitted documentation
MUST explain why using a port number in the Dynamic Ports range is
unsuitable for the given application.
Ports in the Well Known Ports range (0-1023) are also available
for registration through IANA. Because the Well Known Ports range
is both the smallest and the most densely allocated, the requirements
for new allocations are more strict than those for the Registered Ports
range, and will only be granted under the "IETF Review" allocation
procedure . A request for a Well
Known port number MUST document why using a port number from both
the Registered Ports and Dynamic Ports ranges is unsuitable for
the given application.
This section describes the process for requests associated with
IANA's management of the port number and service name registry. Such
requests include initial registration, de-registration, re-use, changes
to the service name, as well as updates to the contact information or
description associated with an assignment. Revocation is initiated by
IANA.
Registration refers to the allocation of port numbers or service
names to applicants. All such registrations are made from port numbers
or service names that are Unassigned or Reserved at the time of the
allocation. Unassigned numbers and names are allocated as needed, and
without further explanation. Reserved numbers and names are assigned
only after review by IANA and the IETF, and are accompanied by a
statement explaining the reason a Reserved number or name is
appropriate for this action.
When a registration for one or more (but not all) transport
protocols is approved, the port number for the non-requested transport
protocol(s) will be marked as Reserved. IANA SHOULD NOT assign that
port number to any other application or service until no other port
numbers remain Unassigned in the requested range. The current
registration owner of a port number MAY register these Reserved port
numbers for other transport protocols when needed.
Service names, on the other hand, are not tied to a specific
transport protocol, and registration requests for only a service name
(but not a port number) allocate that service name for use with all
transport protocols.
A port number or service name registration consists of the
following information:
Registration Owner: Name and email address of the owner of the
registration. This is REQUIRED. For registrations done through
IETF-published RFCs, the registration ownership will belong to the
IETF and not the technical contact persons.
Registration Technical Contact: Name and email address of the
technical contact person for the registration. This is REQUIRED.
For individuals, this is the same as the Registration Owner; for
organizations, this is a point of contact at that organization.
Additional address information MAY be provided. For registrations
done through IETF-published RFCs, one or more technical contact
persons SHALL be provided.
Service Name: A desired unique service name for the service
associated with the registration request MUST be provided, for use
in various service selection and discovery mechanisms (including,
but not limited to, DNS SRV records ). Valid service names MUST only contain
these US-ASCII characters:
letters from A to Z, digits from 0 to 9, and hyphens ("-", ASCII
0x2D or decimal 45). They MUST be at least one character and no
more than fifteen characters long, MUST NOT begin or end with a
hyphen, and MUST NOT consist of only digits (in order to be
distinguishable from port numbers, which are typically written as
all digits). In order to be unique, they MUST NOT be identical to
any currently registered service names in the IANA registry . Service names are case-insensitive;
they may be provided and entered into the registry with mixed case
(e.g., for clarity), but for the purposes of comparison, the case
is ignored.
Port Number: If assignment of port number(s) is desired, either
the currently Unassigned port number(s) the requester suggests for
allocation or the tag "ANY" MUST be provided. If only a service
name is to be assigned, this field MUST be empty. If specific port
numbers are requested, IANA is encouraged to allocate the
suggested numbers. If the tag "ANY" is specified, IANA will choose
a suitable number from the Registered Ports range. Note that the
applicant MUST NOT use the suggested ports prior to the completion
of the registration.
Transport Protocol: The transport protocol(s) for which the
allocation is requested MUST be provided. This field is currently
limited to one or more of TCP, UDP, SCTP, and DCCP.
Service Code: A desired unique service code for the service
associated with the registration request. Service codes are
specific to the DCCP protocol ; the request MUST
include a desired service code when the registration requests
includes DCCP as a transport protocol, and MUST NOT include one
otherwise.
Description: A short description of the service associated with
the registration request is REQUIRED. It should avoid all but the
most well known acronyms.
Reference: A reference document describing the protocol or
application using this port, including whether the protocol
supports either broadcast, multicast, or anycast communication.
For registration requests for Registered Ports, this documentation
MUST explain why a port number in the Dynamic Ports range is
unsuitable for the given application. For registration requests
for Well Known Ports, this documentation MUST explain why a port
number in the Registered Ports or Dynamic Ports ranges is
unsuitable. "Early" registration
requests can be made by IETF working groups without including such
a reference document, although it is RECOMMENDED that at least a
reference to an Internet Draft describing the work in progress is
provided.
When IANA receives a registration request containing the above
information, they SHALL initiate an "Expert Review" in order to determine whether an assignment
should be made. For requests for service names that do not include
port number assignments, IANA MAY, at its discretion, skip the "Expert
Review" procedure and assign the service name under a simple "First
Come First Served" policy .
The original requesters of a granted port number assignment can
return the port number to IANA at any time if they no longer have a
need for it. The port number will be de-registered and will be marked
as Reserved. IANA should not re-assign port numbers that have been
de-registered until all other available port numbers in the specific
range have been assigned.
Before proceeding with a port number de-registration, IANA needs to
reasonably establish that the value is actually no longer in use.
Because there is much less danger of exhausting the service name
space compared to the port number space, it is RECOMMENDED that a
given service name remain assigned even after all associated port
number assignments have become de-registered. Under this policy, it will
appear in the registry as if it had been created through a service
name registration request that did not include any port numbers.
On rare occasions, it may still be useful to de-register a service
name. In such cases, IANA will mark the service name as Reserved. IANA
will involve their IESG-appointed expert in such cases.
If the original requesters of a granted port number assignment no
longer have a need for the registered number, but would like to re-use
it for a different application, they can submit a request to IANA to
do so.
Logically, port number re-use is to be thought of as a
de-registration () followed by an
immediate re-registration () of the
same port number for a new application. Consequently, the information
that needs to be provided about the proposed new use of the port
number is identical to what would need to be provided for a new port
number allocation for the specific ports range.
Because there is much less danger of exhausting the service name
space compared to the port number space, it is RECOMMENDED that the
original service name associated with the prior use of the port number
remains assigned, and a new service be created and associated with the
port number. This is again consistent with viewing a re-use request as
a de-registration followed by an immediate re-registration. Re-using
an assigned service name for a different application is NOT
RECOMMENDED.
IANA needs to carefully review such requests before approving them.
In some instances, the Expert Reviewer will determine that the
application that the port number was assigned to has found usage
beyond the original requester, or that there is a concern that it may
have such users. This determination MUST be made quickly. A community
call concerning revocation of a port number (see below) MAY be
considered, if a broader use of the port number is suspected.
A port number revocation can be thought of as an IANA-initiated
de-registration (), and has
exactly the same effect on the registry.
Sometimes, it will be clear that a specific port number is no
longer in use and that IANA can revoke it and mark it as Reserved. At
other times, it may be unclear whether a given assigned port number is
still in use somewhere in the Internet. In those cases, IANA must
carefully consider the consequences of revoking the port number, and
SHOULD only do so if there is an overwhelming need.
With the help of their IESG-appointed Expert Reviewer, IANA SHALL
formulate a request to the IESG to issue a four-week community call
concerning the pending port number revocation. The IESG and IANA, with
the Expert Reviewer's support, SHALL determine promptly after the end
of the community call whether revocation should proceed and then
communicate their decision to the community. This procedure typically
involves similar steps to de-registration except that it is initiated
by IANA.
Because there is much less danger of exhausting the service name
space compared to the port number space, revoking service names is NOT
RECOMMENDED.
The value of port numbers and service names is defined by their
careful management as a shared Internet resource, whereas enabling
transfer allows the potential for associated monetary exchanges. As a
result, the IETF does not permit port number or service name
assignments to be transferred between parties, even when they are
mutually consenting.
The appropriate alternate procedure is a coordinated
de-registration and registration: The new party requests the port
number or service name via a registration and the previous party
releases its assignment via the de-registration procedure outlined
above.
With the help of their IESG-appointed Expert Reviewer, IANA SHALL
carefully determine if there is a valid technical, operational or
managerial reason before performing the transfer.
The previous procedures help IANA manage the defining properties of
the port name and service name registry. There are additional
procedures which are administrative and help IANA maintain
non-defining information in a registration. This includes changes to
the Port Description and changes to Technical Contact information.
(Note that Registration Owner cannot be changed; see above.) These changes are coordinated by
IANA in an informal manner, and may be initiated by either the
registrant or by IANA, e.g., the latter when requesting an update to
current contact information.
The IANA guidelines described in this document do not change the
security properties of UDP, TCP, SCTP, or DCCP.
Assignment
of a port number or service name does not in any way imply an
endorsement of an application or product, and the fact that network
traffic is flowing to or from a registered port number does not mean
that it is "good" traffic, or even that it is used by the assigned
service. Firewall and system administrators should choose how to
configure their systems based on their knowledge of the traffic in
question, not whether there is a port number or service name registered
or not.
Services are expected to include support for security, either
as default or dynamically negotiated in-band.
The use of separate port number or service name assignments for secure and insecure variants of the same service is to be avoided in order to discourage the deployment of insecure services.
This document obsoletes Sections 8 and 9.1 of the March 2000 IANA
Allocation Guidelines .
Upon approval of this document, IANA is requested to contact the
maintainer of the registry, in order to
merge the contents of that private registry into the official IANA
registry. It is expected that the contents of will at that time be replaced with pointers to
the IANA registry and to this RFC.
Similarly, IANA is instructed to create a new service name entry in the port number registry for any entry in the "Protocol and Service Names" registry that does not already have one assigned. After that, IANA should investigate if the "Protocol and Service Names" registry can be retired.
defines which character strings
are well-formed service names, which until now had not been clearly
defined. The definition in was
chosen to allow maximum compatibility of service names with current
and future service discovery mechanisms.
As of August 5, 2009 approximately 98% of the so-called "Short
Names" from existing port number registrations meet the rules for legal service names
stated in , and hence will be used
unmodified.
The remaining approximately 2% of the exiting "Short Names" are not
suitable to be used directly as well-formed service names because they
contain illegal characters such as asterisks, dots, plusses, slashes,
or underscores. All existing "Short Names" conform to the length
requirement of 15 characters or less. For these unsuitable "Short
Names", listed in the table below, the service name will be the Short
Name with any illegal characters replaced by hyphens. IANA SHALL add
an alias to the registry that assigns a well-formed service name for
the existing service but otherwise duplicates the original assignment
information. In the description field of the new alias, IANA SHALL
record that it assigns a well-formed service name for the previous
service and point to the original assignment. In the description field
of the original assignment, IANA SHALL add a note that the service
name is historic, is not usable with many common service discovery
mechanisms, and provide a reference to the new alias, which can be
used in this way.
Names containing illegal characters to be replaced by hyphens:
914c/g
acmaint_dbd
acmaint_transd
atex_elmd
avanti_cdp
badm_priv
badm_pub
bdir_priv
bdir_pub
bmc_ctd_ldap
bmc_patroldb
boks_clntd
boks_servc
boks_servm
broker_service
bues_service
canit_store
cedros_fds
cl/1
contamac_icm
corel_vncadmin
csc_proxy
cvc_hostd
dbcontrol_agent
dec_dlm
dl_agent
documentum_s
dsmeter_iatc
dsx_monitor
elpro_tunnel
elvin_client
elvin_server
encrypted_admin
erunbook_agent
erunbook_server
esri_sde
EtherNet/IP-1
EtherNet/IP-2
event_listener
flr_agent
gds_db
ibm_wrless_lan
iceedcp_rx
iceedcp_tx
iclcnet_svinfo
idig_mux
ife_icorp
instl_bootc
instl_boots
intel_rci
interhdl_elmd
lan900_remote
LiebDevMgmt_A
LiebDevMgmt_C
LiebDevMgmt_DM
mapper-ws_ethd
matrix_vnet
mdbs_daemon
menandmice_noh
msl_lmd
nburn_id
ncr_ccl
nds_sso
netmap_lm
nms_topo_serv
notify_srvr
novell-lu6.2
nuts_bootp
nuts_dem
ocs_amu
ocs_cmu
pipe_server
pra_elmd
printer_agent
redstorm_diag
redstorm_find
redstorm_info
redstorm_join
resource_mgr
rmonitor_secure
rsvp_tunnel
sai_sentlm
sge_execd
sge_qmaster
shiva_confsrvr
sql*net
srvc_registry
stm_pproc
subntbcst_tftp
udt_os
universe_suite
veritas_pbx
vision_elmd
vision_server
wrs_registry
z39.50
In the case of "whois++", the service name will be
"whoisplusplus".
Two Well Known UDP and TCP ports, 1021 and 1022, have been reserved
for experimental use . This document
registers the same port numbers for SCTP and DCCP, and also instructs
IANA to automatically register these two port numbers for any new
transport protocol that will in the future share the port number
namespace.
Note that these port numbers are meant for temporary
experimentation and development in controlled environments. Before
using these port numbers, carefully consider the advice in in this document, as well as in Sections 1
and 1.1 of "Assigning Experimental and Testing Numbers Considered
Useful" . Most importantly, application
developers must request a permanent port number assignment from IANA
as described in before any kind of
non-experimental deployment.
Registration Technical Contact
IESG <iesg@ietf.org>
Registration Owner
IETF <iesg@ietf.org>
Transport Protocol
SCTP, DCCP
Port Number
1021
Port Name
RFC3692-style Experiment 1
Service Name
exp1
Reference
[RFCyyyy]
Registration Technical Contact
IESG <iesg@ietf.org>
Registration Owner
IETF <iesg@ietf.org>
Transport Protocol
SCTP, DCCP
Port Number
1022
Port Name
RFC3692-style Experiment 2
Service Name
exp2
Reference
[RFCyyyy]
[RFC Editor Note: Please change "yyyy" to the RFC number allocated
to this document before publication.]
This document updates the IANA allocation procedures for the DCCP
Port Number and DCCP Service Codes Registries .
Service Codes are allocated first-come-first-served according to
Section 19.8 of the DCCP specification . This document updates that section by
extending the guidelines given there in the following ways:
IANA MAY assign new Service Codes without seeking Expert
Review using their discretion, but SHOULD seek expert review if
a request seeks more than five Service Codes.
IANA should feel free to contact the DCCP Expert Reviewer
with questions on any registry, regardless of the registry
policy, for clarification or if there is a problem with a
request .
The DCCP ports registry is defined by Section 19.9 of the DCCP
specification . Allocations in this
registry require prior allocation of a Service Code. Not all Service
Codes require IANA-registered ports. This document updates that
section by extending the guidelines given there in the following
way:
IANA should normally assign a value in the range 1024-49151
to a DCCP server port. IANA allocation requests to allocate port
numbers in the Well Known Ports range (0 through 1023), require
an "IETF Review" prior to
allocation by IANA .
IANA MUST NOT allocate a single Service Code value to more
than one DCCP server port.
The set of Service Code values associated with a DCCP server
port should be recorded in the ports registry.
A request for additional Service Codes to be associated with
an already allocated Port Number requires Expert Review. These
requests will normally be accepted when they originate from the
contact associated with the port registration. In other cases,
these applications will be expected to use an unallocated port,
when this is available.
The DCCP specification notes that
a short port name MUST be associated with each DCCP server port that
has been registered. This document requires that this name MUST be
unique.
The text in is based on a suggestion by
Tom Phelan.
Lars Eggert is partly funded by the Trilogy Project , a research project supported by the European
Commission under its Seventh Framework Program.
Application for System (Well Known) Port Number
Application for User (Registered) Port Number
Port Numbers Registry
Protocol and Service Names Registry
DNS SRV Service Types Registry
Trilogy Project
Internet Gateway Device (IGD) V 1.0
UPnP Forum