GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


rfc:rfc5482

Network Working Group L. Eggert Request for Comments: 5482 Nokia Category: Standards Track F. Gont

                                                               UTN/FRH
                                                            March 2009
                      TCP User Timeout Option

Status of This Memo

 This document specifies an Internet standards track protocol for the
 Internet community, and requests discussion and suggestions for
 improvements.  Please refer to the current edition of the "Internet
 Official Protocol Standards" (STD 1) for the standardization state
 and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

 Copyright (c) 2009 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents in effect on the date of
 publication of this document (http://trustee.ietf.org/license-info).
 Please review these documents carefully, as they describe your rights
 and restrictions with respect to this document.

Abstract

 The TCP user timeout controls how long transmitted data may remain
 unacknowledged before a connection is forcefully closed.  It is a
 local, per-connection parameter.  This document specifies a new TCP
 option -- the TCP User Timeout Option -- that allows one end of a TCP
 connection to advertise its current user timeout value.  This
 information provides advice to the other end of the TCP connection to
 adapt its user timeout accordingly.  Increasing the user timeouts on
 both ends of a TCP connection allows it to survive extended periods
 without end-to-end connectivity.  Decreasing the user timeouts allows
 busy servers to explicitly notify their clients that they will
 maintain the connection state only for a short time without
 connectivity.

Eggert & Gont Standards Track [Page 1] RFC 5482 TCP User Timeout Option March 2009

Table of Contents

 1. Introduction ....................................................2
 2. Conventions .....................................................3
 3. Operation .......................................................4
    3.1. Changing the Local User Timeout ............................5
    3.2. UTO Option Reliability .....................................8
    3.3. Option Format ..............................................8
    3.4. Reserved Option Values .....................................9
 4. Interoperability Issues .........................................9
    4.1. Middleboxes ................................................9
    4.2. TCP Keep-Alives ...........................................10
 5. Programming and Manageability Considerations ...................10
 6. Security Considerations ........................................10
 7. IANA Considerations ............................................12
 8. Acknowledgments ................................................12
 9. References .....................................................12
    9.1. Normative References ......................................12
    9.2. Informative References ....................................13

1. Introduction

 The Transmission Control Protocol (TCP) specification [RFC0793]
 defines a local, per-connection "user timeout" parameter that
 specifies the maximum amount of time that transmitted data may remain
 unacknowledged before TCP will forcefully close the corresponding
 connection.  Applications can set and change this parameter with OPEN
 and SEND calls.  If an end-to-end connectivity disruption lasts
 longer than the user timeout, a sender will receive no
 acknowledgments for any transmission attempt, including keep-alives,
 and it will close the TCP connection when the user timeout occurs.
 This document specifies a new TCP option -- the TCP User Timeout
 Option (UTO) -- that allows one end of a TCP connection to advertise
 its current user timeout value.  This information provides advice to
 the other end of the connection to adapt its user timeout
 accordingly.  That is, TCP remains free to disregard the advice
 provided by the UTO option if local policies suggest it to be
 appropriate.
 Increasing the user timeouts on both ends of a TCP connection allows
 it to survive extended periods without end-to-end connectivity.
 Decreasing the user timeouts allows busy servers to explicitly notify
 their clients that they will maintain the connection state only for a
 short time without connectivity.

Eggert & Gont Standards Track [Page 2] RFC 5482 TCP User Timeout Option March 2009

 In the absence of an application-specified user timeout, the TCP
 specification [RFC0793] defines a default user timeout of 5 minutes.
 The Host Requirements RFC [RFC1122] refines this definition by
 introducing two thresholds, R1 and R2 (R2 > R1), that control the
 number of retransmission attempts for a single segment.  It suggests
 that TCP should notify applications when R1 is reached for a segment,
 and close the connection when R2 is reached.  [RFC1122] also defines
 the recommended values for R1 (3 retransmissions) and R2 (100
 seconds), noting that R2 for SYN segments should be at least 3
 minutes.  Instead of a single user timeout, some TCP implementations
 offer finer-grained policies.  For example, Solaris supports
 different timeouts depending on whether a TCP connection is in the
 SYN-SENT, SYN-RECEIVED, or ESTABLISHED state [SOLARIS].
 Although some TCP implementations allow applications to set their
 local user timeout, TCP has no in-protocol mechanism to signal
 changes to the local user timeout to the other end of a connection.
 This causes local changes to be ineffective in allowing a connection
 to survive extended periods without connectivity, because the other
 end will still close the connection after its user timeout expires.
 The ability to inform the other end of a connection about the local
 user timeout can improve TCP operation in scenarios that are
 currently not well supported.  One example of such a scenario is
 mobile hosts that change network attachment points.  Such hosts,
 maybe using Mobile IP [RFC3344], HIP [RFC4423], or transport-layer
 mobility mechanisms [TCP_MOB], are only intermittently connected to
 the Internet.  In between connected periods, mobile hosts may
 experience periods without end-to-end connectivity.  Other factors
 that can cause transient connectivity disruptions are high levels of
 congestion or link or routing failures inside the network.  In these
 scenarios, a host may not know exactly when or for how long
 connectivity disruptions will occur, but it might be able to
 determine an increased likelihood for such events based on past
 mobility patterns and thus benefit from using longer user timeouts.
 In other scenarios, the time and duration of a connectivity
 disruption may even be predictable.  For example, a node in space
 might experience connectivity disruptions due to line-of-sight
 blocking by planetary bodies.  The timing of these events may be
 computable from orbital mechanics.

2. Conventions

 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 [RFC2119].

Eggert & Gont Standards Track [Page 3] RFC 5482 TCP User Timeout Option March 2009

3. Operation

 Use of the TCP User Timeout Option can be either enabled on a per-
 connection basis, e.g., through an API option, or controlled by a
 system-wide setting.  TCP maintains four per-connection state
 variables to control the operation of the UTO option, three of which
 (ADV_UTO, ENABLED, and CHANGEABLE) are new:
 USER_TIMEOUT
    TCP's USER TIMEOUT parameter, as specified in [RFC0793].
 ADV_UTO
    UTO option advertised to the remote TCP peer.  This is an
    application-specified value, and may be specified on a system-wide
    basis.  If unspecified, it defaults to the default system-wide
    USER TIMEOUT.
 ENABLED (Boolean)
    Flag that controls whether the UTO option is enabled for a
    connection.  This flag applies to both sending and receiving.
    Defaults to false.
 CHANGEABLE (Boolean)
    Flag that controls whether USER_TIMEOUT (TCP's USER TIMEOUT
    parameter) may be changed based on an UTO option received from the
    other end of the connection.  Defaults to true and becomes false
    when an application explicitly sets USER_TIMEOUT.
 Note that an exchange of UTO options between both ends of a
 connection is not a binding negotiation.  Transmission of a UTO
 option is a suggestion that the other end consider adapting its user
 timeout.  This adaptation only happens if the other end of the
 connection has explicitly allowed it (both ENABLED and CHANGEABLE are
 true).
 Before opening a connection, an application that wishes to use the
 UTO option enables its use by setting ENABLED to true.  It may choose
 an appropriate local UTO by explicitly setting ADV_UTO; otherwise,
 UTO is set to the default USER TIMEOUT value.  Finally, the
 application should determine whether it will allow the local USER
 TIMEOUT to change based on received UTO options from the other end of
 a connection.  The default is to allow this for connections that do
 not have specific user timeout concerns.  If an application
 explicitly sets the USER_TIMEOUT, CHANGEABLE MUST become false in
 order to prevent UTO options (from the other end) from overriding
 local application requests.  Alternatively, applications can set or
 clear CHANGEABLE directly through API calls.

Eggert & Gont Standards Track [Page 4] RFC 5482 TCP User Timeout Option March 2009

 Performing these steps before an active or passive open causes UTO
 options to be exchanged in the SYN and SYN-ACK packets and is a
 reliable way to initially exchange, and potentially adapt to, UTO
 values.  TCP implementations MAY provide system-wide default settings
 for the ENABLED, ADV_UTO and CHANGEABLE connection parameters.
 In addition to exchanging UTO options in the SYN segments, a
 connection that has enabled UTO options SHOULD include a UTO option
 in the first packet that does not have the SYN flag set.  This helps
 to minimize the amount of state information TCP must keep for
 connections in non-synchronized states.  Also, it is particularly
 useful when mechanisms such as "SYN cookies" [RFC4987] are
 implemented, allowing a newly-established TCP connection to benefit
 from the information advertised by the UTO option, even if the UTO
 contained in the initial SYN segment was not recorded.
 A host that supports the UTO option SHOULD include one in the next
 possible outgoing segment whenever it starts using a new user timeout
 for the connection.  This allows the other end of the connection to
 adapt its local user timeout accordingly.  A TCP implementation that
 does not support the UTO option MUST silently ignore it [RFC1122],
 thus ensuring interoperability.
 Hosts MUST impose upper and lower limits on the user timeouts they
 use for a connection.  Section 3.1 discusses user timeout limits and
 potentially problematic effects of some user timeout settings.
 Finally, it is worth noting that TCP's option space is limited to 40
 bytes.  As a result, if other TCP options are in use, they may
 already consume all the available TCP option space, thus preventing
 the use of the UTO option specified in this document.  Therefore, TCP
 option space issues should be considered before enabling the UTO
 option.

3.1. Changing the Local User Timeout

 When a host receives a TCP User Timeout Option, it must decide
 whether to change the local user timeout of the corresponding
 connection.  If the CHANGEABLE flag is false, USER_TIMEOUT MUST NOT
 be changed, regardless of the received UTO option.  Without this
 restriction, the UTO option would modify TCP semantics, because an
 application-requested USER TIMEOUT could be overridden by peer
 requests.  In this case TCP SHOULD, however, notify the application
 about the user timeout value received from the other end system.

Eggert & Gont Standards Track [Page 5] RFC 5482 TCP User Timeout Option March 2009

 In general, unless the application on the local host has requested a
 specific USER TIMEOUT for the connection, CHANGEABLE will be true and
 hosts SHOULD adjust the local TCP USER TIMEOUT (USER_TIMEOUT) in
 response to receiving a UTO option, as described in the remainder of
 this section.
 The UTO option specifies the user timeout in seconds or minutes,
 rather than in number of retransmissions or round-trip times (RTTs).
 Thus, the UTO option allows hosts to exchange user timeout values
 from 1 second to over 9 hours at a granularity of seconds, and from 1
 minute to over 22 days at a granularity of minutes.
 Very short USER TIMEOUT values can affect TCP transmissions over
 high-delay paths.  If the user timeout occurs before an
 acknowledgment for an outstanding segment arrives, possibly due to
 packet loss, the connection closes.  Many TCP implementations default
 to USER TIMEOUT values of a few minutes.  Although the UTO option
 allows suggestion of short timeouts, applications advertising them
 should consider these effects.
 Long USER TIMEOUT values allow hosts to tolerate extended periods
 without end-to-end connectivity.  However, they also require hosts to
 maintain the TCP state information associated with connections for
 long periods of time.  Section 6 discusses the security implications
 of long timeout values.
 To protect against these effects, implementations MUST impose limits
 on the user timeout values they accept and use.  The remainder of
 this section describes a RECOMMENDED scheme to limit TCP's USER
 TIMEOUT based on upper and lower limits.
 Under the RECOMMENDED scheme, and when CHANGEABLE is true, each end
 SHOULD compute the local USER TIMEOUT for a connection according to
 this formula:
 USER_TIMEOUT = min(U_LIMIT, max(ADV_UTO, REMOTE_UTO, L_LIMIT))
 Each field is to be interpreted as follows:
 USER_TIMEOUT
    USER TIMEOUT value to be adopted by the local TCP for this
    connection.
 U_LIMIT
    Current upper limit imposed on the user timeout of a connection by
    the local host.

Eggert & Gont Standards Track [Page 6] RFC 5482 TCP User Timeout Option March 2009

 ADV_UTO
    User timeout advertised to the remote TCP peer in a TCP User
    Timeout Option.
 REMOTE_UTO
    Last user timeout value received from the other end in a TCP User
    Timeout Option.
 L_LIMIT
    Current lower limit imposed on the user timeout of a connection by
    the local host.
 The RECOMMENDED formula results in the maximum of the two advertised
 values, adjusted for the configured upper and lower limits, to be
 adopted for the user timeout of the connection on both ends.  The
 rationale is that choosing the maximum of the two values will let the
 connection survive longer periods without end-to-end connectivity.
 If the end that announced the lower of the two user timeout values
 did so in order to reduce the amount of TCP state information that
 must be kept on the host, it can close or abort the connection
 whenever it wants.
 It must be noted that the two endpoints of the connection will not
 necessarily adopt the same user timeout.
 Enforcing a lower limit (L_LIMIT) prevents connections from closing
 due to transient network conditions, including temporary congestion,
 mobility hand-offs, and routing instabilities.
 An upper limit (U_LIMIT) can reduce the effect of resource exhaustion
 attacks.  Section 6 discusses the details of these attacks.
 Note that these limits MAY be specified as system-wide constants or
 at other granularities, such as on per-host, per-user, per-outgoing-
 interface, or even per-connection basis.  Furthermore, these limits
 need not be static.  For example, they MAY be a function of system
 resource utilization or attack status and could be dynamically
 adapted.
 The Host Requirements RFC [RFC1122] does not impose any limits on the
 length of the user timeout.  However, it recommends a time interval
 of at least 100 seconds.  Consequently, the lower limit (L_LIMIT)
 SHOULD be set to at least 100 seconds when following the RECOMMENDED
 scheme described in this section.  Adopting a user timeout smaller
 than the current retransmission timeout (RTO) for the connection
 would likely cause the connection to be aborted unnecessarily.
 Therefore, the lower limit (L_LIMIT) MUST be larger than the current

Eggert & Gont Standards Track [Page 7] RFC 5482 TCP User Timeout Option March 2009

 retransmission timeout (RTO) for the connection.  It is worth noting
 that an upper limit may be imposed on the RTO, provided it is at
 least 60 seconds [RFC2988].

3.2. UTO Option Reliability

 The TCP User Timeout Option is an advisory TCP option that does not
 change processing of subsequent segments.  Unlike other TCP options,
 it need not be exchanged reliably.  Consequently, the specification
 does not define a reliability handshake for UTO option exchanges.
 When a segment that carries a UTO option is lost, the other end will
 simply not have the opportunity to update its local USER TIMEOUT.
 Implementations MAY implement local mechanisms to improve delivery
 reliability, such as retransmitting a UTO option when they retransmit
 a segment that originally carried it, or "attaching" the option to a
 byte in the stream and retransmitting the option whenever that byte
 or its ACK are retransmitted.
 It is important to note that although these mechanisms can improve
 transmission reliability for the UTO option, they do not guarantee
 delivery (a three-way handshake would be required for this).
 Consequently, implementations MUST NOT assume that UTO options are
 transmitted reliably.

3.3. Option Format

 Sending a TCP User Timeout Option informs the other end of the
 connection of the current local user timeout and suggests that the
 other end adapt its user timeout accordingly.  The user timeout value
 included in a UTO option contains the ADV_UTO value that is expected
 to be adopted for the TCP's USER TIMEOUT parameter during the
 synchronized states of a connection (ESTABLISHED, FIN-WAIT-1, FIN-
 WAIT-2, CLOSE-WAIT, CLOSING, or LAST-ACK).  Connections in other
 states MUST use the default timeout values defined in [RFC0793] and
 [RFC1122].
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Kind = 28   |   Length = 4  |G|        User Timeout         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 (One tick mark represents one bit.)
            Figure 1: Format of the TCP User Timeout Option

Eggert & Gont Standards Track [Page 8] RFC 5482 TCP User Timeout Option March 2009

 Figure 1 shows the format of the TCP User Timeout Option.  It
 contains these fields:
 Kind (8 bits)
    This MUST be 28, i.e., the TCP option number [RFC0793] that has
    been assigned by IANA (see Section 7).
 Length (8 bits)
    Length of the TCP option in octets [RFC0793]; its value MUST be 4.
 Granularity (1 bit)
    Granularity bit, indicating the granularity of the "User Timeout"
    field.  When set (G = 1), the time interval in the "User Timeout"
    field MUST be interpreted as minutes.  Otherwise (G = 0), the time
    interval in the "User Timeout" field MUST be interpreted as
    seconds.
 User Timeout (15 bits)
    Specifies the user timeout suggestion for this connection.  It
    MUST be interpreted as a 15-bit unsigned integer.  The granularity
    of the timeout (minutes or seconds) depends on the "G" field.

3.4. Reserved Option Values

 A TCP User Timeout Option with a "User Timeout" field of zero and a
 "Granularity" bit of either minutes (1) or seconds (0) is reserved
 for future use.  Current TCP implementations MUST NOT send it and
 MUST ignore it upon reception.

4. Interoperability Issues

 This section discusses interoperability issues related to introducing
 the TCP User Timeout Option.

4.1. Middleboxes

 A TCP implementation that does not support the TCP User Timeout
 Option MUST silently ignore it [RFC1122], thus ensuring
 interoperability.  In a study of the effects of middleboxes on
 transport protocols, Medina et al. have shown that the vast majority
 of modern TCP stacks correctly handle unknown TCP options [MEDINA].
 In this study, 3% of connections failed when an unknown TCP option
 appeared in the middle of a connection.  Because the number of
 failures caused by unknown options is small and they are a result of
 incorrectly implemented TCP stacks that violate existing requirements
 to ignore unknown options, they do not warrant special measures.
 Thus, this document does not define a mechanism to negotiate support
 of the TCP User Timeout Option during the three-way handshake.

Eggert & Gont Standards Track [Page 9] RFC 5482 TCP User Timeout Option March 2009

 Implementations may want to exchange UTO options on the very first
 data segments after the three-way handshake to determine if such a
 middlebox exists on the path.  When segments carrying UTO options are
 persistently lost, an implementation should turn off the use of UTO
 for the connection.  When the connection itself is reset, an
 implementation may be able to transparently re-establish another
 connection instance that does not use UTO before any application data
 has been successfully exchanged.
 Stateful firewalls usually time out connection state after a period
 of inactivity.  If such a firewall exists along the path, it may
 close or abort connections regardless of the use of the TCP User
 Timeout Option.  In the future, such firewalls may learn to parse the
 TCP User Timeout Option in unencrypted TCP segments and adapt
 connection state management accordingly.

4.2. TCP Keep-Alives

 Some TCP implementations, such as those in BSD systems, use a
 different abort policy for TCP keep-alives than for user data.  Thus,
 the TCP keep-alive mechanism might abort a connection that would
 otherwise have survived the transient period without connectivity.
 Therefore, if a connection that enables keep-alives is also using the
 TCP User Timeout Option, then the keep-alive timer MUST be set to a
 value larger than that of the adopted USER TIMEOUT.

5. Programming and Manageability Considerations

 The IETF specification for TCP [RFC0793] includes a simple, abstract
 application programming interface (API).  Similarly, the API for the
 UTO extension in Section 3 is kept abstract.  TCP implementations,
 however, usually provide more complex and feature-rich APIs.  The
 "socket" API that originated with BSD Unix and is now standardized by
 POSIX is one such example [POSIX].  It is expected that TCP
 implementations that choose to include the UTO extension will extend
 their API to allow applications to use and configure its parameters.
 The MIB objects defined in [RFC4022] and [RFC4898] allow management
 of TCP connections.  It is expected that revisions to these documents
 will include definitions of objects for managing the UTO extension
 defined in this document.

6. Security Considerations

 Lengthening user timeouts has obvious security implications.
 Flooding attacks cause denial of service by forcing servers to commit
 resources for maintaining the state of throw-away connections.
 However, TCP implementations do not become more vulnerable to simple

Eggert & Gont Standards Track [Page 10] RFC 5482 TCP User Timeout Option March 2009

 SYN flooding by implementing the TCP User Timeout Option, because
 user timeouts exchanged during the handshake only affect the
 synchronized states (ESTABLISHED, FIN-WAIT-1, FIN-WAIT-2, CLOSE-WAIT,
 CLOSING, LAST-ACK), which simple SYN floods never reach.
 However, when an attacker completes the three-way handshakes of its
 throw-away connections, it can amplify the effects of resource
 exhaustion attacks because the attacked server must maintain the
 connection state associated with the throw-away connections for
 longer durations.  Because connection state is kept longer, lower-
 frequency attack traffic, which may be more difficult to detect, can
 already exacerbate resource exhaustion.
 Several approaches can help mitigate this issue.  First,
 implementations can require prior peer authentication, e.g., using
 IPsec [RFC4301] or TCP-MD5 [RFC2385], before accepting long user
 timeouts for the peer's connections.  (Implementors that decide to
 use TCP-MD5 for this purpose are encouraged to monitor the
 development of TCP-AO [AUTH_OPT], its designated successor, and
 update their implementation when it is published as an RFC.)  A
 similar approach is for a host to start accepting long user timeouts
 for an established connection only after in-band authentication has
 occurred, for example, after a TLS handshake across the connection
 has succeeded [RFC5246].  Although these are arguably the most
 complete solutions, they depend on external mechanisms to establish a
 trust relationship.
 A second alternative that does not depend on external mechanisms
 would introduce a per-peer limit on the number of connections that
 may use increased user timeouts.  Several variants of this approach
 are possible, such as fixed limits or shortening accepted user
 timeouts with a rising number of connections.  Although this
 alternative does not eliminate resource exhaustion attacks from a
 single peer, it can limit their effects.  Reducing the number of
 high-UTO connections a server supports in the face of an attack turns
 that attack into a denial-of-service attack against the service of
 high-UTO connections.
 Per-peer limits cannot protect against distributed denial-of-service
 attacks, where multiple clients coordinate a resource exhaustion
 attack that uses long user timeouts.  To protect against such
 attacks, TCP implementations could reduce the duration of accepted
 user timeouts with increasing resource utilization.
 TCP implementations under attack may be forced to shed load by
 resetting established connections.  Some load-shedding heuristics,
 such as resetting connections with long idle times first, can
 negatively affect service for intermittently connected, trusted peers

Eggert & Gont Standards Track [Page 11] RFC 5482 TCP User Timeout Option March 2009

 that have suggested long user timeouts.  On the other hand, resetting
 connections to untrusted peers that use long user timeouts may be
 effective.  In general, using the peers' level of trust as a
 parameter during the load-shedding decision process may be useful.
 Note that if TCP needs to close or abort connections with a long TCP
 User Timeout Option to shed load, these connections are still no
 worse off than without the option.
 Finally, upper and lower limits on user timeouts, discussed in
 Section 3.1, can be an effective tool to limit the impact of these
 sorts of attacks.

7. IANA Considerations

 This section is to be interpreted according to [RFC5226].
 This document does not define any new namespaces.  IANA has allocated
 a new 8-bit TCP option number (28) for the UTO option from the "TCP
 Option Kind Numbers" registry maintained at http://www.iana.org.

8. Acknowledgments

 The following people have improved this document through thoughtful
 suggestions: Mark Allman, Caitlin Bestler, David Borman, Bob Braden,
 Scott Brim, Marcus Brunner, Wesley Eddy, Gorry Fairhurst, Abolade
 Gbadegesin, Ted Faber, Guillermo Gont, Tom Henderson, Joseph Ishac,
 Jeremy Harris, Alfred Hoenes, Phil Karn, Michael Kerrisk, Dan Krejsa,
 Jamshid Mahdavi, Kostas Pentikousis, Juergen Quittek, Anantha
 Ramaiah, Joe Touch, Stefan Schmid, Simon Schuetz, Tim Shepard, and
 Martin Stiemerling.
 Lars Eggert is partly funded by [TRILOGY], a research project
 supported by the European Commission under its Seventh Framework
 Program.
 Fernando Gont wishes to thank Secretaria de Extension Universitaria
 at Universidad Tecnologica Nacional and Universidad Tecnologica
 Nacional/Facultad Regional Haedo for supporting him in this work.

9. References

9.1. Normative References

 [RFC0793]   Postel, J., "Transmission Control Protocol", STD 7,
             RFC 793, September 1981.
 [RFC1122]   Braden, R., "Requirements for Internet Hosts -
             Communication Layers", STD 3, RFC 1122, October 1989.

Eggert & Gont Standards Track [Page 12] RFC 5482 TCP User Timeout Option March 2009

 [RFC2119]   Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC5226]   Narten, T. and H. Alvestrand, "Guidelines for Writing an
             IANA Considerations Section in RFCs", BCP 26, RFC 5226,
             May 2008.

9.2. Informative References

 [AUTH_OPT]  Touch, J., Mankin, A., and R. Bonica, "The TCP
             Authentication Option", Work in Progress, November 2008.
 [MEDINA]    Medina, A., Allman, M., and S. Floyd, "Measuring
             Interactions Between Transport Protocols and
             Middleboxes", Proc. 4th ACM SIGCOMM/USENIX Conference on
             Internet Measurement, October 2004.
 [POSIX]     IEEE Std. 1003.1-2001, "Standard for Information
             Technology - Portable Operating System Interface
             (POSIX)", Open Group Technical Standard: Base
             Specifications Issue 6, ISO/IEC 9945:2002, December 2001.
 [RFC2385]   Heffernan, A., "Protection of BGP Sessions via the TCP
             MD5 Signature Option", RFC 2385, August 1998.
 [RFC2988]   Paxson, V. and M. Allman, "Computing TCP's Retransmission
             Timer", RFC 2988, November 2000.
 [RFC3344]   Perkins, C., "IP Mobility Support for IPv4", RFC 3344,
             August 2002.
 [RFC4022]   Raghunarayan, R., "Management Information Base for the
             Transmission Control Protocol (TCP)", RFC 4022,
             March 2005.
 [RFC4301]   Kent, S. and K. Seo, "Security Architecture for the
             Internet Protocol", RFC 4301, December 2005.
 [RFC4423]   Moskowitz, R. and P. Nikander, "Host Identity Protocol
             (HIP) Architecture", RFC 4423, May 2006.
 [RFC4898]   Mathis, M., Heffner, J., and R. Raghunarayan, "TCP
             Extended Statistics MIB", RFC 4898, May 2007.
 [RFC4987]   Eddy, W., "TCP SYN Flooding Attacks and Common
             Mitigations", RFC 4987, August 2007.

Eggert & Gont Standards Track [Page 13] RFC 5482 TCP User Timeout Option March 2009

 [RFC5246]   Dierks, T. and E. Rescorla, "The Transport Layer Security
             (TLS) Protocol Version 1.2", RFC 5246, August 2008.
 [SOLARIS]   Sun Microsystems, "Solaris Tunable Parameters Reference
             Manual", Part No. 806-7009-10, 2002.
 [TCP_MOB]   Eddy, W., "Mobility Support For TCP", Work in Progress,
             April 2004.
 [TRILOGY]   "Trilogy Project", <http://www.trilogy-project.org/>.

Authors' Addresses

 Lars Eggert
 Nokia Research Center
 P.O. Box 407
 Nokia Group  00045
 Finland
 Phone: +358 50 48 24461
 EMail: lars.eggert@nokia.com
 URI:   http://research.nokia.com/people/lars_eggert/
 Fernando Gont
 Universidad Tecnologica Nacional / Facultad Regional Haedo
 Evaristo Carriego 2644
 Haedo, Provincia de Buenos Aires  1706
 Argentina
 Phone: +54 11 4650 8472
 EMail: fernando@gont.com.ar
 URI:   http://www.gont.com.ar/

Eggert & Gont Standards Track [Page 14]

/data/webs/external/dokuwiki/data/pages/rfc/rfc5482.txt · Last modified: 2009/03/16 16:50 by 127.0.0.1

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki