DCCP WG G.Fairhurst
Internet Draft University of Aberdeen
Expires: September 2007 March 2, 2007
The DCCP Service Code
draft-fairhurst-dccp-serv-codes-03.txt
Status of this Memo
By submitting this Internet-Draft, each author represents that
any applicable patent or other IPR claims of which he or she is
aware have been or will be disclosed, and any of which he or she
becomes aware will be disclosed, in accordance with Section 6 of
BCP 79.
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
This Internet-Draft will expire on September 2, 2007.
Abstract
This document describes the usage of Service Codes by the Datagram
Congestion Control Protocol, RFC 4340. Service Codes provide a method
to identify the intended service/application to process a DCCP
Connection Request. This provides improved flexibility in the use and
assignment of port numbers for connection multiplexing. The DCCP
Service Code can also enable more explicit coordination of services
behind NATs and firewalls. This document motivates the setting of
Service Codes by applications, rather than assigning a default
Service Code value of zero.
G. Fairhurst Expires September 2, 2007 [Page 1]
Internet-Draft DCCP Service Codes March 2007
Table of Contents
1. Introduction...................................................3
1.1. Conventions used in this document.........................4
2. An Architecture for supporting Service Codes...................5
2.1. IANA Port Numbers.........................................5
2.2. DCCP Service Code Values..................................6
2.3. Zero Service Code.........................................6
2.4. Reception of a DCCP-Request with a bound Service Code.....6
2.5. Reception of a DCCP-Request with an unbound Service Code..7
2.6. SDP for describing Service Codes..........................7
2.7. Service Code Registry.....................................7
3. Use of the DCCP Service Code...................................7
3.1. Setting Service Codes at the Sender.......................8
3.2. Using Service Codes in the Network........................8
3.3. Using Service Codes at the Receiver.......................8
3.4. Multiple Associations of Service Codes and Ports at the
Sender.........................................................9
3.5. Summary of Service Code and Port Handling................10
4. Implementation Support for Service Codes......................11
4.1. Minimal Support..........................................11
4.2. Standard Support.........................................11
4.3. Enhanced Support.........................................11
5. Changes required to the API to support Service Codes..........12
5.1. Interactions with IPsec..................................12
6. Service Code Registry.........................................13
7. Benchmarking Services Described in this document..............13
7.1. Echo.....................................................13
7.2. Daytime..................................................13
7.3. Character generator......................................13
7.4. Time service.............................................14
7.5. PerfTest service.........................................14
8. Security Considerations.......................................15
8.1. Interactions of Service Codes and port numbers...........15
9. IANA Considerations...........................................16
9.1. Port number values allocated by this document............16
9.2. Service Code values allocated by this document...........16
10. Conclusions..................................................17
11. Acknowledgments..............................................17
12. References...................................................18
12.1. Normative References....................................18
12.2. Informative References..................................18
Author's Addresses...............................................19
Intellectual Property Statement..................................20
Disclaimer of Validity...........................................20
Copyright Statement....................Error! Bookmark not defined.
Acknowledgment...................................................21
Fairhurst Expires September 2, 2007 [Page 2]
Internet-Draft DCCP Service Codes March 2007
1. Introduction
Most Internet transport protocols use "well-known" port numbers
[RFC814] to indicate which application service is associated with a
connection or message; this includes TCP [RFC793], UDP [RFC768], SCTP
[RFC2960], UDP-Lite [RFC3828], and DCCP [RFC4340]. Making a port
number well-known involves registration with the Internet Assigned
Numbers Authority (IANA), which includes defining a service by a
unique keyword and reserving a port number from among a fixed pool
[IANA].
DCCP specifies a Service Code as a 4-byte value (32 bits). This
describes the application-level service to which a client application
wishes to connect ([RFC4340], Section 8.1.2). A service code
identifies the protocol (or a standard profile, e.g. [ID.DCCP.RTP])
to be used at the application layer. It is not intended to be used to
specify a variant of an application, or a specific variant of a
protocol.
Service Codes allow a flexible correspondence between application-
layer services and port numbers, which affects how applications
interact with DCCP. This decouples the use of ports for connection
demultiplexing and state management from their use to indicate a
desired service.
The use of Service Codes can assist in identifying the correct
intended service when the server is located behind a NAT that
modifies the port numbers associated with a flow.
Middle-boxes (e.g. NATs, Firewalls) that desire to identify the type
of data being transported by a flow, can utilize the Service Code for
this purpose. When consistently used, the Service Code can provide a
more specific indication of the actual service (e.g. indicating the
type of multimedia flow, or intended application behaviour).
Use of a Service Code value, instead of binding a service to a
particular publicly-known port number, also permits a larger number
of concurrent connections for a particular service. For example, this
may be useful for applications where servers need to handle very
large numbers of simultaneous open ports to the same service.
If an application does not set a Service Code, the connection is
associated with a Service Code of zero, with the intended server
identified only by the destination port number.
Fairhurst Expires September 2, 2007 [Page 3]
Internet-Draft DCCP Service Codes March 2007
1.1. 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].
Fairhurst Expires September 2, 2007 [Page 4]
Internet-Draft DCCP Service Codes March 2007
2. An Architecture for supporting Service Codes
DCCP defines the use of a combination of ports and Service Codes to
identify the server application ([RFC4340], 8.1.2). These are
described in the following sections. Section 3 describes the use of
Service Codes by end hosts and network middleboxes.
2.1. IANA Port Numbers
In DCCP, an endpoint address is associated with a port number,
forming a socket; and a pair of sockets uniquely identifies each
connection. Ports provide the fundamental de-multiplexing function.
Like DCCP, most Internet Transport Protocols (e.g. TCP [RFC793], UDP
[RFC768]) also define publicly-known ports for most services, whether
intended for public access (e.g., telnet, DNS) or for services
typically used between pre-arranged pairs (e.g., X11, SSL). In TCP
and UDP these are the primary means of identifying the required
service when a connection request is received.
The Internet Assigned Numbers Authority currently manages the set of
globally reserved port numbers [IANA]. The destination port value
that is associated with a service is determined either by an
operating system index to a copy of the IANA table (e.g.,
getportbyname() in Unix, which indexes the /etc/services file), or
directly mapped by the application.
The UDP and TCP port number space: 0..65535, is split into three
ranges [RFC2780]:
o 0..1023 "well-known", also called "system" ports
o 1024..49151 "registered", also called "user" ports
o 49152..65535 "dynamic", also called "private" ports
One challenge with the use of IANA-managed ports is that this
allocates ports globally, for all hosts on the public Internet, even
though the association between a port and a service is of interest
only to the end hosts participating in a connection. As a result, the
fixed space of port numbers is being globally reserved unnecessarily.
It is more useful to allocate this name space on a per-host basis
[ID.Portnames].
Well-known/Reserved DCCP ports are described in a separate IANA
registry [RFC4340]. This registry may also associate ports with a
pre-defined set of Service Codes (see section 2.2).
Fairhurst Expires September 2, 2007 [Page 5]
Internet-Draft DCCP Service Codes March 2007
The source port associated with a connection request, often known as
the "ephemeral port", traditionally includes the range 49152-65535,
and should also include the 1024-49151 range. The value used for
the ephemeral port is usually chosen by the client operating system.
It has been suggested that a randomized choice of port number value
can help defend against "blind" attacks [ID.TSVWG.RAND]. Such methods
may also be applicable to IETF-defined transport protocols, including
DCCP.
2.2. DCCP Service Code Values
DCCP specifies a 4 byte Service Code [RFC4340]. Service codes may be
represented in one of three forms: as a decimal number (the canonical
method), as a 4 character ASCII string, or as a hexadecimal number.
The Service Code identifies the application-level service to which a
client application wishes to connect. It is present only in DCCP-
Request and DCCP-Response packets and permits a more flexible
correspondence between services and port numbers than is possible
using the corresponding socket pair (4-tuple of layer-3 addresses and
layer-4 ports). This decouples the use of ports for connection
demultiplexing and state management, from their use to indicate a
desired endpoint service.
One method of operation is to assign one Service Code per Port,
although multiple applications may be permitted on the same port (if
a Server implementation permits this).
Service Codes allow a larger number of concurrent connections for a
particular service than possible using well-known port numbers, by
allowing endpoints to allocate their own port numbers separately,
based on services they deploy (c.f. section 2.1).
2.3. Zero Service Code
A Service Code value of zero indicates that the Service Code function
is not used by a client. A server uses only the destination port
number to identify the required application (as in section 2.1).
2.4. Reception of a DCCP-Request with a bound Service Code
A Service Code value may be associated by the client (initiator of
the DCCP-Request), and is used by the server (recipient of the DCCP-
Request) to associate the connection with the corresponding
application. This association MUST be explicit (i.e. the requested
Service Code MUST have been previously bound to the destination port
at the server). Once connected, the server returns a copy of the
Fairhurst Expires September 2, 2007 [Page 6]
Internet-Draft DCCP Service Codes March 2007
Service Code in the DCCP-Response packet completing the initial
handshake [RFC4340].
2.5. Reception of a DCCP-Request with an unbound Service Code
DCCP defines a number of possible error conditions that may arise in
processing of a Connection Request:
o Connection Refused (Invalid port)
o Too Busy (Service Code/Port may be valid)
o Bad Service Code (Invalid Service Code for specified port)
Reception of a DCCP-Request with an invalid destination port MUST
result in the DCCP-Request being rejected, and sending a DCCP-Reset
with Reset Code "Connection Refused". A server MAY also use the Reset
Code "Too Busy" ([RFC4340], 8.1.3).
Reception of a DCCP-Request for a port number where the Service Code
that is not bound MUST result in the DCCP-Request being rejected, and
returning a DCCP-Reset with Reset Code "Bad Service Code" ([RFC4340],
8.1.2).
2.6. SDP for describing Service Codes
Methods that currently signal the use of port numbers, such as the
Session Description Protocol (SDP) require extension to support DCCP
Service Codes [ID.DCCP.RTP].
2.7. Service Code Registry
The set of Service Codes currently specified for use within the
general Internet are defined in an IANA-controlled name space. IANA
manages new allocations of Service Codes in this space [RFC4340].
Service Code bindings to Ports may also be defined in the IANA DCCP
Port Registry.
3. Use of the DCCP Service Code
Like UDP, DCCP uses port numbers to demultiplex connections. Upon
receipt of a DCCP-Request including the Service Code, the Code is
matched against a list of available services.
Fairhurst Expires September 2, 2007 [Page 7]
Internet-Draft DCCP Service Codes March 2007
3.1. Setting Service Codes at the Sender
Applications SHOULD specify an appropriate Service Code when sending
a DCCP-Request packet. Valid Service Codes should be selected from
the set of values assigned in the DCCP Service Code Registry
maintained by IANA [IANA-SC], or from the uncoordinated private space
([RFC4340], 8.1.2.). An application that does not set a Service Code,
SHOULD be associated with a Service Code value of zero.
3.2. Using Service Codes in the Network
Port numbers and IP addresses are the accepted methods to identify a
flow within an IP network. When the DCCP header has not been
encrypted, Middleboxes [RFC3234], such as firewalls, can instead use
the Service Code to identify the application (even when running on a
non-standard port). Middlebox devices are therefore expected to check
Service Code values before port numbers for DCCP. The Service Code
values on DCCP-Requests should be used for supplementary checks
[RFC4340]. Section 4.1 describes some issues that may arise in this
case.
The use of the DCCP Service Code can potentially lead to interactions
with other protocols that interpret or modify DCCP port numbers. This
includes IPsec and other firewall systems, other security mechanisms,
other in-band exchange of port numbers, and network address
translators (NATs).
Network address and port translators, known collectively as NATs, not
only interpret DCCP ports, but may also translate/modify them
[RFC2993]. This interferes with the use of ports for service
identification [RFC3234]. The DCCP Service Code may allow services to
be identified behind NATs if NATs are not further extended to
translate Service Codes. Middleboxes should not modify the Service
Code unless they change the service that a connection is accessing.
DCCP connections identified by the Service Code continue to use IP
addresses and ports, although neither port number may be well-
known/reserved. Translation of these ports need to be considered in
the operation of NATs. In addition, DCCP Service Codes can reduce the
need to correctly interpret port numbers, leading to new
opportunities for network address and port translators.
3.3. Using Service Codes at the Receiver
An implementation MUST allow a server application to bind to a
Service Code on a fixed port. The Service Code of zero may be the
default, indicating that no specific Service Code is in use.
Fairhurst Expires September 2, 2007 [Page 8]
Internet-Draft DCCP Service Codes March 2007
An implementation MAY allow server applications to bind to a Service
Code specifying a set of acceptable ports.
The DCCP Service Codes associates a DCCP Connection with the service
that the client expects to be running at the server. This value MUST
take precedence over any service bound to the port number. Two cases
can occur:
o When a DCCP-Request packet is received with a Service Code value
of zero, the connection is associated with an application using
the destination port number specified in the DCCP-Request. If
there is no specific application associated with the destination
port, then the connection MUST be aborted and a DCCP-RESET packet
is returned. If the port is not associated with a zero Service
Code, then the connection is aborted.
o A DCCP-Request that is received with a non-zero Service Code MUST
be checked to validate that the server has associated the Service
Code with the specified destination port. If the Service Code is
associated with the port, the corresponding server application is
used. If there is no associated application, the server MUST abort
the connection by issuing a DCCP-Reset with the reset code "Bad
Service Code".
3.4. Multiple Associations of Service Codes and Ports at the Sender
A single Service Code MAY be bound to more than one destination port
(wildcarding a set of port values). Also a single destination port
MAY be bound to multiple Service Codes (wildcarding a set of Service
Codes), although an active connection may only be associated with a
single Service Code [RFC4340].
o An end host implementation may provide a method that only allows a
single Service Code to be associated with each listening port.
This means that a single port may be used only for a pre-specified
service; however this service does not need to be permanently
running at the Server. The arrival of a DCCP-Request may therefore
require launching an application to accept messages from the DCCP
connection. This operation could resemble that of "portmapper" or
"inetd".
Fairhurst Expires September 2, 2007 [Page 9]
Internet-Draft DCCP Service Codes March 2007
o When a Connection Request is received with a port number that is
associated with multiple Service Codes, the listening server needs
to provide a method to ensure that the DCCP-Request is associated
with an application server that handles the corresponding Service
Code. This may require launching an application to accept messages
from the DCCP connection. This use may allow a server to offer
more than the limit of 65,536 services determined by the size of
the Port field (fewer if system/user/dynamic boundaries are
preserved). The limit is based solely on the number of unique
connections between two hosts (i.e., 4,294,967,296).
As in the previous section, when the specified Service Code is not
associated with the specified port, the server MUST abort the
connection and send a DCCP Reset message.
3.5. Summary of Service Code and Port Handling
The basic operation of the Service Codes is as follows:
o A source host may issue a DCCP-Request with a Service Code of zero
and chooses either a well-known/reserved destination port or a
port number announced by some other means.
o A source host may issue a DCCP-Request with a non-zero Service
Code and chooses a destination port number that is associated with
the specified Service Code at the destination.
o The destination host, upon receiving a DCCP-Request with a zero
Service Code, validates that the port supports a Service Code of
zero and then uses the destination port to identify the associated
server.
o The destination host, upon receiving a DCCP-Request with a non-
zero Service Code, determines whether an available service
matching the Service Code is supported for the specified
destination port.
o If the service is available, the session is associated with a
corresponding server, and a DCCP-Response is returned.
o If the service is not available, the session is aborted and a
DCCP-Reset packet is returned.
Fairhurst Expires September 2, 2007 [Page 10]
Internet-Draft DCCP Service Codes March 2007
4. Implementation Support for Service Codes
This document does not define how to implement Service Codes on a
particular platform or using a specific operating system. It does
define three levels of support that may be offered.
>>> This section needs further work, ideas are welcome! <<<
4.1. Minimal Support
All Servers MUST be capable of accepting a DCCP-Request that contains
a zero Service Code. These may be handled in the same way as other
transport connections (e.g. UDP, TCP). In this level, a DCCP-Request
with a non-zero Service Code MUST result in the connection being
aborted. This limits interoperability with other levels. This model
is suitable for platforms with limited capability, but is NOT
RECOMMENDED for general use.
4.2. Standard Support
In this level of support, a server MAY accept a DCCP-Request that
contains a zero Service Code. Each Service Code specified in a DCCP-
Request message is checked against an internal database to determine
the permitted port range that may be associated with the Service
Code. This model is RECOMMENDED for general use.
The design could be simplified if one Default Service code were to be
associated with a set of specific well-known ports, allowing a port
to be mapped via a library or operating system function to their
default Service Code (simplifying the binding). Such a system needs
however also MUST provide a way to allow a sending and/or receiving
application to bind to a none-default Service Code (specified by the
application). It should also be noted that some higher layer
protocols are not associated with a single well-known port and that
they must therefore use this latter method.
4.3. Enhanced Support
A server operating at the enhanced level provides finer and more
flexible control of the use of Service Codes and Port numbers. This
permits a receiver to accept DCCP-Requests with arbitrary mappings
between Service Codes and port ranges, associating each connection
with the appropriate application server. This level of support may
require operating systems to use a modified process to handle in-
coming DCCP requests and may allow policies to be defined.
Fairhurst Expires September 2, 2007 [Page 11]
Internet-Draft DCCP Service Codes March 2007
5. Changes required to the API to support Service Codes
The use of Service Codes requires an API that allows a service to
bind to a Service Code as well as a port number. One approach is to
use separate commands as follows:
o Extend the existing port number indicator command (e.g., Unix
bind() or connect() calls) to select a specific port number where
desired.
o Extend the existing socket parameterization command (e.g., Unix
setsockopt()) to set a service-code option.
o An information base (table) may be used by servers to identify the
set of Service Codes that are associated with each port and the
corresponding set of server applications.
XXX Author note:
May need to discuss:
get_port_and_service_code_by_name(char *what_service_do_you_want)
char *get_service_code_by_number(unsigned sc)
and interactions with getadddrinfo() address/port lookup routine,
which has been introduced to simplify the migration to IPv6
([RFC3493], 6.1).
XXX End Author Note.
5.1. Interactions with IPsec
IPsec uses port numbers to perform access control in transport mode
[RFC4301]. Security policies can define port-specific access control
(PROTECT, BYPASS, DISCARD), as well as port-specific algorithms and
keys. Similarly, firewall policies allow or block traffic based on
port numbers.
Use of port numbers in IPsec selectors and firewalls may assume that
the numbers correspond to well-known services. It is useful to note
that there is no such requirement; any service may run on any port,
subject to mutual agreement between the endpoint hosts. Use of the
Service Code may interfere with this assumption both within IPsec and
in other firewall systems, but it does not add a new vulnerability.
New implementations of IPsec and firewall systems may interpret the
Fairhurst Expires September 2, 2007 [Page 12]
Internet-Draft DCCP Service Codes March 2007
Service Code when implementing policy rules, but should not rely on
either port numbers or Service Codes to indicate a specific service.
This is not an issue for IPsec because the entire DCCP header and
payload are protected by all IPsec modes. None of the DCCP header is
protected by application-layer security, e.g., DTLS [ID.DTLS.DCCP],
so again this is not an issue [RFC4347].
6. Service Code Registry
The set of Service Codes currently specified for use within the
general Internet are defined in an IANA-controlled name space. IANA
manages new allocations of Service Codes in this space [RFC4340].
Service Code bindings to Ports may also be defined in the IANA DCCP
Port Registry.
7. Benchmarking Services Described in this document
A number of simple services are commonly supported by systems using
DCCP and UDP, this section defines corresponding services for DCCP.
These services are useful to debug and benchmark bidirectional DCCP
connections. The IANA section of this document allocates a
corresponding set of code points for these services.
7.1. Echo
The operation of the DCCP Echo service follows that specified for UDP
[RFC862]: a server listens for DCCP connections; once a client has
set up a connection, each data packet sent to the server will be
copied (echoed) back to the client.
7.2. Daytime
The DCCP daytime service is operationally equivalent to the
connection-based TCP daytime service [RFC867]: any data received is
discarded by the server; and generates a response sent in a DCCP data
packet containing the current time and data as an ASCII string; after
which the connection is closed.
7.3. Character generator
The operation of the DCCP chargen service corresponds to the
connection-based TCP chargen protocol [RFC864]: A server listens for
Fairhurst Expires September 2, 2007 [Page 13]
Internet-Draft DCCP Service Codes March 2007
incoming requests and, once a client has established a connection,
continuously sends datagrams containing a random number (between 0
and 512, up to the current path MTU) of characters. The service
terminates when the user either closes or aborts the connection.
Congestion control is enforced using the mechanisms [RFC4340] and
related documents.
If necessary the receiver can enforce flow control on this service by
using either or both of the Slow Receiver ([RFC4340], 11.6) and Data
Dropped ([RFC4340], 11.7) options to signal the server to slow down.
The chargen protocol provides a useful service that may be used for
testing and measurement of bidirectional DCCP connectivity, as well
as congestion control responsiveness. The datagram-based variant of
chargen can be emulated with the DCCP ECHO service by changing the
format of the datagrams sent by the client, hence these services
complement each other.
7.4. Time service
The format of timestamps and the operation of the DCCP time service
is equivalent with the TCP time protocol variant [RFC868]: a server
listens for incoming connections; after a client has established a
new connection, the server sends a 4-byte timestamp; whereupon the
client closes the connection.
7.5. PerfTest service
The PerfTest concept specified by this document provides a generic
service that may be used to benchmark and measure both unidirectional
and bidirectional DCCP connections, as well as server and host DCCP
stacks.
This document defines a generic PerfTest service. The payload of DCCP
packets associated with the DCCP PerfTest service are silently
discarded by the receiver, and used only for gathering numerical
performance data.
The PerfTest server is identified by a combination of the port number
and DCCP Service Code. It does not recommend a specific benchmarking
software to use, but does allocate a port number specified that
currently coincides with that of the open-source iperf benchmarking
program [iperf].
Fairhurst Expires September 2, 2007 [Page 14]
Internet-Draft DCCP Service Codes March 2007
8. Security Considerations
This document does not describe new protocol functions.
The document discusses the usage of Service Codes. There are three
areas of security that are important:
1. Interaction with NATs and firewalls (see section 3.2, on middlebox
behaviour).
2. Interaction with IPsec and DTLS security (see section 4.1, on use
of IPsec).
3. Interpretation of DCCP Service Codes over-riding traditional use
of reserved/well-known port numbers (see section 7.1)
4. Services used for benchmarking and testing may also be used to
generate traffic for other purposes, and pose an opportunity for a
Denial of Service attack. Care needs to be exercised when enabling
these services in an operational network, or appropriate rate-
limits should be provided to mitigate these effects.
8.1. Interactions of Service Codes and port numbers
The Service Code value may be used to over-ride the traditional way
that operating systems consider low-numbered ports as privileged.
This represents a change in the way operating systems respect this
range of DCCP port numbers.
The same service (application) may be potentially accessed using more
than one Service Code. Examples include the use of separate Service
Codes for an application layered directly upon DCCP and one using
DTLS transport over DCCP. Other possibilities include the use of a
private Service Code point that maps to the same application as
assigned to an IANA-defined Service Code value. Different versions of
a service (application) may also be mapped to a corresponding set of
Service Code values. Care needs to be exercised when interpreting the
mapping the Service Code value to the corresponding service.
Processing of Service Codes may imply more processing than currently
associated with incoming port numbers. Implementers need to guard
against increasing opportunities for Denial of Service attack.
Fairhurst Expires September 2, 2007 [Page 15]
Internet-Draft DCCP Service Codes March 2007
9. IANA Considerations
A set of new services are defined in section 6 and are summarized in
this section.
9.1. Port number values allocated by this document
This document requests allocation of the following code points from
the IANA DCCP Port numbers registry:
>>>>>> IANA ACTION Please replace IANA THIS RFC, with the allocated
RFC number. <<<
echo 7/dccp Echo SC:ECHO
# IETF dccp WG, [IANA - THIS RFC]
daytime 13/dccp DayTime SC:DTIM
# IETF dccp WG, [IANA - THIS RFC]
chatgen 19/dccp Chargen SC:CHAR
# IETF dccp WG, [IANA - THIS RFC]
time 37/dccp Timeserver SC:TIME
# IETF dccp WG, [IANA - THIS RFC]
perf 5001/dccp PerfTest SC:PERF
# IETF dccp WG, [IANA - THIS RFC]
9.2. Service Code values allocated by this document
This document solicits IANA action to allocate the following code
points from the Service Code registry [IANA-SC]. The requested
assignments are listed below and summarized in table 1. This set of
Service Codes may be utilized for testing DCCP implementations and
transmission paths.
+----------+------+----+-------------------------------+----------+
| Service | ASCII|Port| Description | Ref |
| Code (SC)| Code | | | |
+----------+------+----+-------------------------------+----------+
|0x4543484f| ECHO | 7| Echo service | [RFC862] |
|0x4454494d| DTIM | 13| Daytime server | [RFC867] |
|0x43484152| CHAR | 19| Character generator (chargen) | [RFC864] |
|0x54494d45| TIME | 37| Timeserver | [RFC868] |
|0x50455246| PERF |5001| Performance tests (e.g. | * |
| | | | iperf, ttcp, ...) | |
+----------+------+----+-------------------------------+----------+
Table 1: Allocation of Service Codes by this document.
Fairhurst Expires September 2, 2007 [Page 16]
Internet-Draft DCCP Service Codes March 2007
Notes:
1) Port is the default port associated with this service.
2) * Reference is this document.
The document notes that it is NOT required to supply an approved
document (e.g. a published RFC) to support an application for a DCCP
Service Code or port number value, although RFCs may be used to
request Service Code values via the IANA Considerations section (e.g.
[ID.DTLS.DCCP], [ID.DCCP.RTP]).
10. Conclusions
This document discusses the operation of service codes by the DCCP
transport protocol [RFC4340] and motivates their use. The document
augments and clarifies the way in which DCCP applications should use
the Service Code Feature. It does not update or obsolete the protocol
defined in RFC4340.
Service Codes, or similar concepts may also be useful to other IETF
Transport Protocols [ID.Portnames]).
11. Acknowledgments
This work has been supported by the EC IST SatSix Project.
Significant contributions to this document resulted from discussion
with Joe Touch, and this is gratefully acknowledged. The author also
thanks Ian McDonald and the DCCP WG for helpful comments on this
topic, and Gerrit Renker for his help in determining DCCP behaviour,
review of the document, and compilation of useful test applications
defined in the IANA section of this document.
Fairhurst Expires September 2, 2007 [Page 17]
Internet-Draft DCCP Service Codes March 2007
12. References
12.1. Normative References
[RFC1122] Braden, R. (ed.), "Requirements for Internet Hosts:
Communication Layers, " STD 3, RFC 1122, Oct. 1989
(STANDARD).
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997 (BEST
CURRENT PRACTICE).
[RFC4340] Kohler, E., M. Handley, S. Floyd, "Datagram Congestion
Control Protocol (DCCP)", RFC 4340, Mar. 2006 (PROPOSED
STANDARD).
12.2. Informative References
[IANA] Internet Assigned Numbers Authority, www.iana.org
[IANA-SC] IANA DCCP Service Code Registry
http://www.iana.org/assignments/service-codes
[ID.Portnames] J. Touch, "A TCP Option for Port Names", IETF Work in
Progress, draft-touch-tcp-portnames-00.txt.
[ID.DTLS.DCCP] T.Phelan, "Datagram Transport Layer Security (DTLS)
over the Datagram Congestion Control Protocol (DCCP)", IETF
Work in Progress, draft-phelan-dccp-dtls-01.txt.
[ID.DCCP.RTP] C. Perkins, "RTP and the Datagram Congestion Control
Protocol (DCCP)", IETF Work in Progress, draft-ietf-dccp-
rtp-01.txt.
[ID.TSVWG.RAND] M. Larsen, F. Gont, "Port Randomization", IETF Work
in Progress, draft-larsen-tsvwg-port-randomization-00.
[iperf] http://dast.nlanr.net/Projects/Iperf/
[RFC768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
August 1980.
[RFC793] Postel, J., "Transmission Control Protocol", STD 7, RFC
793, Sept. 1981 (STANDARD).
[RFC814] Clark, D., "NAME, ADDRESSES, PORTS, AND ROUTES", RFC 814,
July 1982 (UNKNOWN).
Fairhurst Expires September 2, 2007 [Page 18]
Internet-Draft DCCP Service Codes March 2007
[RFC862] Postel, J., "Echo Protocol", STD 20, RFC 862, May 1983.
[RFC864] Postel, J., "Character Generator Protocol", STD 22, RFC
864, May 1983.
[RFC867] Postel, J., "Daytime Protocol", STD 25, RFC 867, May 1983.
[RFC868] Postel, J. and K. Harrenstien, "Time Protocol", STD 26,
RFC 868, May 1983.
[RFC2780] Bradner, S. and V. Paxson, "IANA Allocation Guidelines For
Values In the Internet Protocol and Related Headers", BCP
37, RFC 2780, March 2000.
[RFC2960] Stewart, R., Xie, Q., Morneault, K., Sharp, C.,
Schwarzbauer, H., Taylor, T., Rytina, I., Kalla, M., Zhang,
L., and V. Paxson, "Stream Control Transmission Protocol",
RFC 2960, October 2000.
[RFC2993] Hain, T., "Architectural Implications of NAT", RFC 2993,
November 2000 (INFORMATIONAL).
[RFC3234] Carpenter, B. and S. Brim, "Middleboxes: Taxonomy and
Issues", RFC 3234, February 2002.
[RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J., and W.
Stevens, "Basic Socket Interface Extensions for IPv6", RFC
3493, February 2003.
[RFC3828] Larzon, L-A., Degermark, M., Pink, S., Jonsson, L-E., and
G. Fairhurst, "The Lightweight User Datagram Protocol (UDP-
Lite)", RFC 3828, July 2004.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005.
[RFC4347] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.1", RFC 4346, April 2006.
Fairhurst Expires September 2, 2007 [Page 19]
Internet-Draft DCCP Service Codes March 2007
13. Author's Addresses
Godred (Gorry) Fairhurst
Department of Engineering
University of Aberdeen
Kings College
Aberdeen, AB24 3UE
UK
Email: gorry@erg.abdn.ac.uk
URL: http://www.erg.abdn.ac.uk/users/gorry
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Disclaimer of Validity
This document and the information contained herein are provided on
an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE
IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL
WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY
WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE
ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE.
Fairhurst Expires September 2, 2007 [Page 20]
Internet-Draft DCCP Service Codes March 2007
Copyright Statement
Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
Fairhurst Expires September 2, 2007 [Page 21]
Internet-Draft DCCP Service Codes March 2007
Change Log.
01 introduced:
- a replacement of the word *range* when referring to sets of dccp
ports (they are not necessarily contiguous), noted by E. Kohler.
- Addition of some Service Codes in IANA section.
02 introduced:
- add the use of profiles with DCCP, identified by Service Code, but
not the use of protocol variants.
- further detail on implementation levels (more input would be good)
- added security consideration for traffic generators
- added ref to UDPL for completeness
- Corrected NiTs found by Gerrit Renker
Fairhurst Expires September 2, 2007 [Page 22]
