draft-ietf-tcpm-converters-03.txt   draft-ietf-tcpm-converters-04.txt 
TCPM Working Group O. Bonaventure, Ed. TCPM Working Group O. Bonaventure, Ed.
Internet-Draft Tessares Internet-Draft Tessares
Intended status: Experimental M. Boucadair, Ed. Intended status: Experimental M. Boucadair, Ed.
Expires: April 21, 2019 Orange Expires: April 25, 2019 Orange
S. Gundavelli S. Gundavelli
Cisco Cisco
S. Seo S. Seo
Korea Telecom Korea Telecom
October 18, 2018 October 22, 2018
0-RTT TCP Convert Protocol 0-RTT TCP Convert Protocol
draft-ietf-tcpm-converters-03 draft-ietf-tcpm-converters-04
Abstract Abstract
This document specifies an application proxy, called Transport This document specifies an application proxy, called Transport
Converter, to assist the deployment of TCP extensions such as Converter, to assist the deployment of TCP extensions such as
Multipath TCP. This proxy is designed to avoid inducing extra delay Multipath TCP. This proxy is designed to avoid inducing extra delay
when involved in a network-assisted connection (that is, 0-RTT). when involved in a network-assisted connection (that is, 0-RTT).
This specification assumes an explicit model, where the proxy is This specification assumes an explicit model, where the proxy is
explicitly configured on hosts. explicitly configured on hosts.
skipping to change at page 1, line 42 skipping to change at page 1, line 42
the Converter Protocol. the Converter Protocol.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 21, 2019. This Internet-Draft will expire on April 25, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
skipping to change at page 2, line 46 skipping to change at page 2, line 46
4.2.3. The Bootstrap TLV . . . . . . . . . . . . . . . . . . 15 4.2.3. The Bootstrap TLV . . . . . . . . . . . . . . . . . . 15
4.2.4. Supported TCP Extension Services TLV . . . . . . . . 15 4.2.4. Supported TCP Extension Services TLV . . . . . . . . 15
4.2.5. Connect TLV . . . . . . . . . . . . . . . . . . . . . 16 4.2.5. Connect TLV . . . . . . . . . . . . . . . . . . . . . 16
4.2.6. Extended TCP Header TLV . . . . . . . . . . . . . . . 18 4.2.6. Extended TCP Header TLV . . . . . . . . . . . . . . . 18
4.2.7. Error TLV . . . . . . . . . . . . . . . . . . . . . . 18 4.2.7. Error TLV . . . . . . . . . . . . . . . . . . . . . . 18
5. Compatibility of Specific TCP Options with the Conversion 5. Compatibility of Specific TCP Options with the Conversion
Service . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Service . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.1. Base TCP Options . . . . . . . . . . . . . . . . . . . . 21 5.1. Base TCP Options . . . . . . . . . . . . . . . . . . . . 21
5.2. Window Scale (WS) . . . . . . . . . . . . . . . . . . . . 22 5.2. Window Scale (WS) . . . . . . . . . . . . . . . . . . . . 22
5.3. Selective Acknowledgements . . . . . . . . . . . . . . . 22 5.3. Selective Acknowledgements . . . . . . . . . . . . . . . 22
5.4. Timestamp . . . . . . . . . . . . . . . . . . . . . . . . 22 5.4. Timestamp . . . . . . . . . . . . . . . . . . . . . . . . 23
5.5. Multipath TCP . . . . . . . . . . . . . . . . . . . . . . 23 5.5. Multipath TCP . . . . . . . . . . . . . . . . . . . . . . 23
5.6. TCP Fast Open . . . . . . . . . . . . . . . . . . . . . . 23 5.6. TCP Fast Open . . . . . . . . . . . . . . . . . . . . . . 23
5.7. TCP User Timeout . . . . . . . . . . . . . . . . . . . . 24 5.7. TCP User Timeout . . . . . . . . . . . . . . . . . . . . 24
5.8. TCP-AO . . . . . . . . . . . . . . . . . . . . . . . . . 24 5.8. TCP-AO . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.9. TCP Experimental Options . . . . . . . . . . . . . . . . 24 5.9. TCP Experimental Options . . . . . . . . . . . . . . . . 25
6. Interactions with Middleboxes . . . . . . . . . . . . . . . . 24 6. Interactions with Middleboxes . . . . . . . . . . . . . . . . 25
7. Security Considerations . . . . . . . . . . . . . . . . . . . 25 7. Security Considerations . . . . . . . . . . . . . . . . . . . 25
7.1. Privacy & Ingress Filtering . . . . . . . . . . . . . . . 25 7.1. Privacy & Ingress Filtering . . . . . . . . . . . . . . . 25
7.2. Authorization . . . . . . . . . . . . . . . . . . . . . . 25 7.2. Authorization . . . . . . . . . . . . . . . . . . . . . . 26
7.3. Denial of Service . . . . . . . . . . . . . . . . . . . . 26 7.3. Denial of Service . . . . . . . . . . . . . . . . . . . . 26
7.4. Traffic Theft . . . . . . . . . . . . . . . . . . . . . . 26 7.4. Traffic Theft . . . . . . . . . . . . . . . . . . . . . . 27
7.5. Multipath TCP-specific Considerations . . . . . . . . . . 26 7.5. Multipath TCP-specific Considerations . . . . . . . . . . 27
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28
8.1. Convert Service Port Number . . . . . . . . . . . . . . . 27 8.1. Convert Service Port Number . . . . . . . . . . . . . . . 28
8.2. The Converter Protocol (Convert) Parameters . . . . . . . 27 8.2. The Converter Protocol (Convert) Parameters . . . . . . . 28
8.2.1. Convert Versions . . . . . . . . . . . . . . . . . . 27 8.2.1. Convert Versions . . . . . . . . . . . . . . . . . . 28
8.2.2. Convert TLVs . . . . . . . . . . . . . . . . . . . . 28 8.2.2. Convert TLVs . . . . . . . . . . . . . . . . . . . . 28
8.2.3. Convert Error Messages . . . . . . . . . . . . . . . 28 8.2.3. Convert Error Messages . . . . . . . . . . . . . . . 29
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 29 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 30
9.1. Contributors . . . . . . . . . . . . . . . . . . . . . . 30 9.1. Contributors . . . . . . . . . . . . . . . . . . . . . . 31
10. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 31 10. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 32
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 31 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 32
11.1. Normative References . . . . . . . . . . . . . . . . . . 31 11.1. Normative References . . . . . . . . . . . . . . . . . . 32
11.2. Informative References . . . . . . . . . . . . . . . . . 32 11.2. Informative References . . . . . . . . . . . . . . . . . 33
Appendix A. Differences with SOCKSv5 . . . . . . . . . . . . . . 35 Appendix A. Differences with SOCKSv5 . . . . . . . . . . . . . . 37
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 37 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 38
1. Introduction 1. Introduction
Transport protocols like TCP evolve regularly [RFC7414]. TCP has Transport protocols like TCP evolve regularly [RFC7414]. TCP has
been improved in different ways. Some improvements such as changing been improved in different ways. Some improvements such as changing
the initial window size [RFC6928] or modifying the congestion control the initial window size [RFC6928] or modifying the congestion control
scheme can be applied independently on clients and servers. Other scheme can be applied independently on clients and servers. Other
improvements such as Selective Acknowledgements [RFC2018] or large improvements such as Selective Acknowledgements [RFC2018] or large
windows [RFC7323] require a new TCP option or to change the semantics windows [RFC7323] require a new TCP option or to change the semantics
of some fields in the TCP header. These modifications must be of some fields in the TCP header. These modifications must be
skipping to change at page 5, line 9 skipping to change at page 5, line 9
The main advantage of network-assisted Converters is that they enable The main advantage of network-assisted Converters is that they enable
new TCP extensions to be used on a subset of the end-to-end path, new TCP extensions to be used on a subset of the end-to-end path,
which encourages the deployment of these extensions. The Transport which encourages the deployment of these extensions. The Transport
Converter allows the client and the server to directly negotiate TCP Converter allows the client and the server to directly negotiate TCP
options. options.
The Convert Protocol is a generic mechanism to provide 0-RTT The Convert Protocol is a generic mechanism to provide 0-RTT
conversion service. As a sample applicability use case, this conversion service. As a sample applicability use case, this
document specifies how the Convert Protocol applies for Multipath document specifies how the Convert Protocol applies for Multipath
TCP. It is out of scope of this document to provide a comprehensive TCP. It is out of scope of this document to provide a comprehensive
list of potential all conversion services; separate documents may be list of all potential conversion services; separate documents may be
edited in the future for other conversion services upon need. edited in the future for other conversion services upon need.
This document does not assume that all the traffic is eligible to the This document does not assume that all the traffic is eligible to the
network-assisted conversion service. Only a subset of the traffic network-assisted conversion service. Only a subset of the traffic
will be forwarded to a Converter according to a set of policies. will be forwarded to a Converter according to a set of policies.
Furthermore, it is possible to bypass the Converter to connect to the Furthermore, it is possible to bypass the Converter to connect to the
servers that already support the required TCP extension. servers that already support the required TCP extension.
This document assumes that a client is configured with one or a list This document assumes that a client is configured with one or a list
of Converters (e.g., [I-D.boucadair-tcpm-dhc-converter]). of Converters (e.g., [I-D.boucadair-tcpm-dhc-converter]).
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Any user data received by the Transport Converter over the upstream Any user data received by the Transport Converter over the upstream
(resp., downstream) connection is relayed over the downstream (resp., (resp., downstream) connection is relayed over the downstream (resp.,
upstream) connection. upstream) connection.
Figure 4 illustrates the establishment of a TCP connection by the Figure 4 illustrates the establishment of a TCP connection by the
Client through a Transport Converter. The information shown between Client through a Transport Converter. The information shown between
brackets is part of the Converter Protocol described later in this brackets is part of the Converter Protocol described later in this
document. document.
Figure 4 illustrates the establishment of a TCP connection by the
Client through a Transport Converter. The information shown between
brackets is part of the Converter Protocol described later in this
document.
Transport Transport
Client Converter Server Client Converter Server
--------------------> -------------------->
SYN TFO [->Server:port] SYN TFO [->Server:port]
--------------------> -------------------->
SYN SYN
<-------------------- <--------------------
SYN+ACK SYN+ACK
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1 2 3 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 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
+---------------+---------------+-------------------------------+ +---------------+---------------+-------------------------------+
| Type | Length | (optional) Value ... | | Type | Length | (optional) Value ... |
+---------------+---------------+-------------------------------+ +---------------+---------------+-------------------------------+
| ... (optional) Value | | ... (optional) Value |
+---------------------------------------------------------------+ +---------------------------------------------------------------+
Figure 10: Converter Generic TLV Format Figure 10: Converter Generic TLV Format
A given TLV LUST only appear once on a connection. If two or more A given TLV MUST only appear once on a connection. If two or more
copies of the same TLV are exchanged over a Converter connection, the instances of the same TLV are exchanged over a Converter connection,
associated TCP connections MUST be closed. All fields are encoded the associated TCP connections MUST be closed.
using the network byte order. The length field is the number of 32
bits words.
4.2.2. Summary of Supported Convert TLVs 4.2.2. Summary of Supported Convert TLVs
This document specifies the following Convert TLVs: This document specifies the following Convert TLVs:
+------+-----+----------+------------------------------------------+ +------+-----+----------+------------------------------------------+
| Type | Hex | Length | Description | | Type | Hex | Length | Description |
+------+-----+----------+------------------------------------------+ +------+-----+----------+------------------------------------------+
| 1 | 0x1 | 1 | Bootstrap TLV | | 1 | 0x1 | 1 | Bootstrap TLV |
| 10 | 0xA | Variable| Connect TLV | | 10 | 0xA | Variable | Connect TLV |
| 20 | 0x14| Variable| Extended TCP Header TLV | | 20 | 0x14| Variable | Extended TCP Header TLV |
| 21 | 0x15| Variable| Supported TCP Extension Services TLV | | 21 | 0x15| Variable | Supported TCP Extension Services TLV |
| 30 | 0x1E| Variable| Error TLV | | 30 | 0x1E| Variable | Error TLV |
+------+-----+----------+------------------------------------------+ +------+-----+----------+------------------------------------------+
Figure 11: The TLVs used by the Converter protocol Figure 11: The TLVs used by the Converter protocol
Type 0x0 is a reserved valued. Implementations MUST discard messages
with such TLV.
To establish a connection via a Transport Converter, a Client MUST To establish a connection via a Transport Converter, a Client MUST
first obtain a valid TFO cookie from that Converter. This is the first obtain a valid TFO cookie from that Converter. This is the
bootstrap procedure during which the Client opens a connection to the bootstrap procedure during which the Client opens a connection to the
Transport Converter with an empty TFO option. According to Transport Converter with an empty TFO option. According to
[RFC7413], the Transport Converter returns its cookie in the SYN+ACK. [RFC7413], the Transport Converter returns its cookie in the SYN+ACK.
Then the Client sends a Bootstrap TLV (Section 4.2.3) to which the Then the Client sends a Bootstrap TLV (Section 4.2.3) to which the
Transport Converter replies with the Supported TCP Extension Services Transport Converter replies with the Supported TCP Extension Services
TLV described in Section 4.2.4. TLV described in Section 4.2.4.
With the TFO cookie of the Transport Converter, the Client can With the TFO cookie of the Transport Converter, the Client can
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connection via a Transport Converter. connection via a Transport Converter.
The 'Remote Peer Port' and 'Remote Peer IP Address' fields contain The 'Remote Peer Port' and 'Remote Peer IP Address' fields contain
the destination port number and IP address of the target server for the destination port number and IP address of the target server for
an outgoing connection towards a server located on the Internet. For an outgoing connection towards a server located on the Internet. For
incoming connections destined to a client serviced via a Converter, incoming connections destined to a client serviced via a Converter,
these fields convey the source port and IP address. these fields convey the source port and IP address.
The Remote Peer IP Address MUST be encoded as an IPv6 address. IPv4 The Remote Peer IP Address MUST be encoded as an IPv6 address. IPv4
addresses MUST be encoded using the IPv4-Mapped IPv6 Address format addresses MUST be encoded using the IPv4-Mapped IPv6 Address format
defined in [RFC4291]. defined in [RFC4291]. Further, Remote Peer IP address field MUST NOT
include multicast, broadcast, and host loopback addresses [RFC6890].
The optional 'TCP Options' field is used to specify how specific TCP The optional 'TCP Options' field is used to specify how specific TCP
Options should be advertised by the Transport Converter to the final Options should be advertised by the Transport Converter to the final
destination of a connection. If this field is not supplied, the destination of a connection. If this field is not supplied, the
Transport Converter MUST use the default TCP options that correspond Transport Converter MUST use the default TCP options that correspond
to its local policy. to its local policy.
The Connect TLV could be designed to be generic to include the DNS The Connect TLV could be designed to be generic to include the DNS
name of the remote peer instead of its IP address as in SOCKS name of the remote peer instead of its IP address as in SOCKS
[RFC1928]. However, that design was not adopted because it induces [RFC1928]. However, that design was not adopted because it induces
both an extra load and increased delays on the Converter to handle both an extra load and increased delays on the Converter to handle
and manage DNS resolution requests. and manage DNS resolution requests.
1 2 3 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 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
+---------------+---------------+-------------------------------+ +---------------+---------------+-------------------------------+
| Type | Length | Remote Peer Port | | Type | Length | Remote Peer Port |
+---------------+---------------+-------------------------------+ +---------------+---------------+-------------------------------+
| | | |
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SHALL present those options to the destination peer in addition to SHALL present those options to the destination peer in addition to
the TCP options that it would have used according to its local the TCP options that it would have used according to its local
policies. For the TCP options that are listed without an optional policies. For the TCP options that are listed without an optional
value, the Converter MUST generate its own value. For the TCP value, the Converter MUST generate its own value. For the TCP
options that are included in the 'TCP Options' field with an optional options that are included in the 'TCP Options' field with an optional
value, it SHALL copy the entire option for use in the connection with value, it SHALL copy the entire option for use in the connection with
the destination peer. This feature is required to support TCP Fast the destination peer. This feature is required to support TCP Fast
Open. Open.
The Converter may discard a Connect TLV request for many reasons The Converter may discard a Connect TLV request for many reasons
(e.g., bad TFO cookie, authorization failed, out of resources). An (e.g., bad TFO cookie, authorization failed, out of resources,
error message indicating the encountered error is returned to the invalid address type). An error message indicating the encountered
requesting Client Section 4.2.7. In order to prevent denial-of- error is returned to the requesting Client (Section 4.2.7). In order
service attacks, error messages sent to a Client SHOULD be rate- to prevent denial-of-service attacks, error messages sent to a Client
limited. SHOULD be rate-limited.
4.2.6. Extended TCP Header TLV 4.2.6. Extended TCP Header TLV
The Extended TCP Header TLV (Figure 16) is used by the Transport The Extended TCP Header TLV (Figure 16) is used by the Transport
Converter to send to the Client the extended TCP header that was Converter to send to the Client the extended TCP header that was
returned by the Server in the SYN+ACK packet. This TLV is only sent returned by the Server in the SYN+ACK packet. This TLV is only sent
if the Client sent a Connect TLV to request the establishment of a if the Client sent a Connect TLV to request the establishment of a
connection. connection.
1 2 3 1 2 3
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unsigned integer. Four classes of errors are defined: unsigned integer. Four classes of errors are defined:
o Message validation and processing errors (0-31 range): returned o Message validation and processing errors (0-31 range): returned
upon reception of an an invalid message (including valid messages upon reception of an an invalid message (including valid messages
but with invalid or unknown TLVs). but with invalid or unknown TLVs).
o Client-side errors (32-63 range): the Client sent a request that o Client-side errors (32-63 range): the Client sent a request that
could not be accepted by the Converter (e.g., unsupported could not be accepted by the Converter (e.g., unsupported
operation). operation).
o Converter-side errors (64-95 range) : problems encountered on the o Converter-side errors (64-95 range): problems encountered on the
Converter (e.g., lack of resources) which prevent it from Converter (e.g., lack of resources) which prevent it from
fulfilling the Client's request. fulfilling the Client's request.
o Errors caused by destination server (96-127 range) : the final o Errors caused by destination server (96-127 range): the final
destination could not be reached or it replied with a reset destination could not be reached or it replied with a reset
message. message.
The following error codes are defined in this document: The following error codes are defined in this document:
o Unsupported Version (0): The version number indicated in the fixed o Unsupported Version (0): The version number indicated in the fixed
header of a message received from a peer is not supported. header of a message received from a peer is not supported.
This error code MUST be generated by a Converter when it receives This error code MUST be generated by a Converter when it receives
a request having a version number that it does not support. a request having a version number that it does not support.
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Converter. When multiple versions are supported by the Converter, Converter. When multiple versions are supported by the Converter,
it includes the list of supported version in the value field; each it includes the list of supported version in the value field; each
version is encoded in 8 bits. version is encoded in 8 bits.
Upon receipt of this error code, the client checks whether it Upon receipt of this error code, the client checks whether it
supports one of the versions returned by the Converter. The supports one of the versions returned by the Converter. The
highest common supported version MUST be used by the client in highest common supported version MUST be used by the client in
subsequent exchanges with the Converter. subsequent exchanges with the Converter.
o Malformed Message (1): This error code is sent to indicate that a o Malformed Message (1): This error code is sent to indicate that a
message can not be successfully parsed. message can not be successfully parsed and validated.
Typically, this error message is sent by the Converter if it
receives a Connect TLV enclosing a multicast, broadcast, or
loopback IP address.
To ease troubleshooting, the value field MUST echo the received To ease troubleshooting, the value field MUST echo the received
message. The Converter and the Client MUST send a RST containing message. The Converter and the Client MUST send a RST containing
this error upon reception of a malformed message. this error upon reception of a malformed message.
o Unsupported Message (2): This error code is sent to indicate that o Unsupported Message (2): This error code is sent to indicate that
a message type is not supported by the Converter. a message type is not supported by the Converter.
To ease troubleshooting, the value field MUST echo the received To ease troubleshooting, the value field MUST echo the received
message. The Converter and the Client MUST send a RST containing message. The Converter and the Client MUST send a RST containing
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5. Compatibility of Specific TCP Options with the Conversion Service 5. Compatibility of Specific TCP Options with the Conversion Service
In this section, we discuss how several standard track TCP options In this section, we discuss how several standard track TCP options
can be supported through the Converter. The non-standard track can be supported through the Converter. The non-standard track
options and the experimental options will be discussed in other options and the experimental options will be discussed in other
documents. documents.
5.1. Base TCP Options 5.1. Base TCP Options
Three TCP options were initially defined in [RFC0793] : End-of-Option Three TCP options were initially defined in [RFC0793]: End-of-Option
List (Kind=0), No-Operation (Kind=1) and Maximum Segment Size List (Kind=0), No-Operation (Kind=1) and Maximum Segment Size
(Kind=2). The first two options are mainly used to pad the TCP (Kind=2). The first two options are mainly used to pad the TCP
extended header. There is no reason for a client to request a extended header. There is no reason for a client to request a
Converter to specifically send these options towards the final Converter to specifically send these options towards the final
destination. destination.
The Maximum Segment Size option (Kind=2) is used by a host to The Maximum Segment Size option (Kind=2) is used by a host to
indicate the largest segment that it can receive over each indicate the largest segment that it can receive over each
connection. This value is function of the stack that terminates the connection. This value is function of the stack that terminates the
TCP connection. There is no reason for a Client to request a TCP connection. There is no reason for a Client to request a
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(Kind=34) in the Bootstrap TLV. If a Transport Converter has (Kind=34) in the Bootstrap TLV. If a Transport Converter has
advertised the support for TCP Fast Open in its Bootstrap TLV, it advertised the support for TCP Fast Open in its Bootstrap TLV, it
needs to be able to process two types of Connect TLV. If such a needs to be able to process two types of Connect TLV. If such a
Transport Converter receives a Connect TLV with the TCP Fast Open Transport Converter receives a Connect TLV with the TCP Fast Open
cookie option that does not contain a cookie, it MUST add an empty cookie option that does not contain a cookie, it MUST add an empty
TCP Fast Open cookie option in the SYN sent to the remote server. If TCP Fast Open cookie option in the SYN sent to the remote server. If
such a Transport Converter receives a Connect TLV with the TCP Fast such a Transport Converter receives a Connect TLV with the TCP Fast
Open cookie option that contains a cookie, it MUST copy the TCP Fast Open cookie option that contains a cookie, it MUST copy the TCP Fast
Open cookie option in the SYN sent to the remote server. Open cookie option in the SYN sent to the remote server.
The Converter may behave in address preservation or address sharing
modes as discussed in Section 5.4 of
[I-D.nam-mptcp-deployment-considerations]. Which behavior to use by
a Converter is deployment-specific. If address sharing mode is
enabled, the Converter MUST adhere to REQ-2 of [RFC6888] which
implies a default "IP address pooling" behavior of "Paired" (as
defined in Section 4.1 of [RFC4787]) must be supported. This
behavior is meant to avoid breaking applications that depend on the
external address remaining constant. Also, maintaining the same
external IP address for a client is meant to preserve the validity of
the TFO cookie.
5.7. TCP User Timeout 5.7. TCP User Timeout
The TCP User Timeout option is defined in [RFC5482]. The associated The TCP User Timeout option is defined in [RFC5482]. The associated
TCP option (Kind=28) does not appear to be widely deployed. TCP option (Kind=28) does not appear to be widely deployed.
Editor's Note: Feedback requested for the utilisation of this option Editor's Note: Feedback requested for the utilisation of this option
by deployed TCP stacks. by deployed TCP stacks.
5.8. TCP-AO 5.8. TCP-AO
skipping to change at page 27, line 21 skipping to change at page 27, line 46
o A device that embeds the Converter may also host a RADIUS client o A device that embeds the Converter may also host a RADIUS client
that will solicit an AAA server to check whether connections that will solicit an AAA server to check whether connections
received from a given source IP address are authorized or not received from a given source IP address are authorized or not
[I-D.boucadair-radext-tcpm-converter]. [I-D.boucadair-radext-tcpm-converter].
A first safeguard against the misuse of Converter resources by A first safeguard against the misuse of Converter resources by
illegitimate users (e.g., users with access networks that are not illegitimate users (e.g., users with access networks that are not
managed by the same provider that operates the Converter) is the managed by the same provider that operates the Converter) is the
Converter to reject Multipath TCP connections received on its Converter to reject Multipath TCP connections received on its
Internet-facing interfaces. Only Multipath PTCP connections received Internet-facing interfaces. Only Multipath TCP connections received
on the customer-facing interfaces of a Converter will be accepted. on the customer-facing interfaces of a Converter will be accepted.
8. IANA Considerations 8. IANA Considerations
8.1. Convert Service Port Number 8.1. Convert Service Port Number
IANA is requested to assign a TCP port number (TBA) for the Converter IANA is requested to assign a TCP port number (TBA) for the Converter
Protocol from the "Service Name and Transport Protocol Port Number Protocol from the "Service Name and Transport Protocol Port Number
Registry" available at https://www.iana.org/assignments/service- Registry" available at https://www.iana.org/assignments/service-
names-port-numbers/service-names-port-numbers.xhtml. names-port-numbers/service-names-port-numbers.xhtml.
skipping to change at page 31, line 29 skipping to change at page 32, line 21
o 00 to -01 : added section Section 5 describing the support of o 00 to -01 : added section Section 5 describing the support of
different standard tracks TCP options by Transport Converters, different standard tracks TCP options by Transport Converters,
clarification of the IANA section, moved the SOCKS comparison to clarification of the IANA section, moved the SOCKS comparison to
the appendix and various minor modifications the appendix and various minor modifications
o 01 to -02 : Minor modifications o 01 to -02 : Minor modifications
o 02 to -03 : Minor modifications o 02 to -03 : Minor modifications
o 03 to -04 : Minor modifications
11. References 11. References
11.1. Normative References 11.1. Normative References
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, [RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
RFC 793, DOI 10.17487/RFC0793, September 1981, RFC 793, DOI 10.17487/RFC0793, September 1981,
<https://www.rfc-editor.org/info/rfc793>. <https://www.rfc-editor.org/info/rfc793>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, <https://www.rfc- DOI 10.17487/RFC2119, March 1997,
editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <https://www.rfc-editor.org/info/rfc4291>. 2006, <https://www.rfc-editor.org/info/rfc4291>.
[RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4, [RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4,
ICMPv6, UDP, and TCP Headers", RFC 4727, ICMPv6, UDP, and TCP Headers", RFC 4727,
DOI 10.17487/RFC4727, November 2006, <https://www.rfc- DOI 10.17487/RFC4727, November 2006,
editor.org/info/rfc4727>. <https://www.rfc-editor.org/info/rfc4727>.
[RFC4987] Eddy, W., "TCP SYN Flooding Attacks and Common [RFC4987] Eddy, W., "TCP SYN Flooding Attacks and Common
Mitigations", RFC 4987, DOI 10.17487/RFC4987, August 2007, Mitigations", RFC 4987, DOI 10.17487/RFC4987, August 2007,
<https://www.rfc-editor.org/info/rfc4987>. <https://www.rfc-editor.org/info/rfc4987>.
[RFC5482] Eggert, L. and F. Gont, "TCP User Timeout Option", [RFC5482] Eggert, L. and F. Gont, "TCP User Timeout Option",
RFC 5482, DOI 10.17487/RFC5482, March 2009, RFC 5482, DOI 10.17487/RFC5482, March 2009,
<https://www.rfc-editor.org/info/rfc5482>. <https://www.rfc-editor.org/info/rfc5482>.
[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP [RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
Authentication Option", RFC 5925, DOI 10.17487/RFC5925, Authentication Option", RFC 5925, DOI 10.17487/RFC5925,
June 2010, <https://www.rfc-editor.org/info/rfc5925>. June 2010, <https://www.rfc-editor.org/info/rfc5925>.
[RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure, [RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure,
"TCP Extensions for Multipath Operation with Multiple "TCP Extensions for Multipath Operation with Multiple
Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013, Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013,
<https://www.rfc-editor.org/info/rfc6824>. <https://www.rfc-editor.org/info/rfc6824>.
[RFC6890] Cotton, M., Vegoda, L., Bonica, R., Ed., and B. Haberman,
"Special-Purpose IP Address Registries", BCP 153,
RFC 6890, DOI 10.17487/RFC6890, April 2013,
<https://www.rfc-editor.org/info/rfc6890>.
[RFC7413] Cheng, Y., Chu, J., Radhakrishnan, S., and A. Jain, "TCP [RFC7413] Cheng, Y., Chu, J., Radhakrishnan, S., and A. Jain, "TCP
Fast Open", RFC 7413, DOI 10.17487/RFC7413, December 2014, Fast Open", RFC 7413, DOI 10.17487/RFC7413, December 2014,
<https://www.rfc-editor.org/info/rfc7413>. <https://www.rfc-editor.org/info/rfc7413>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>. <https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
skipping to change at page 33, line 21 skipping to change at page 34, line 21
Boucadair, M., Jacquenet, C., Bonaventure, O., Behaghel, Boucadair, M., Jacquenet, C., Bonaventure, O., Behaghel,
D., stefano.secci@lip6.fr, s., Henderickx, W., Skog, R., D., stefano.secci@lip6.fr, s., Henderickx, W., Skog, R.,
Vinapamula, S., Seo, S., Cloetens, W., Meyer, U., Vinapamula, S., Seo, S., Cloetens, W., Meyer, U.,
Contreras, L., and B. Peirens, "Extensions for Network- Contreras, L., and B. Peirens, "Extensions for Network-
Assisted MPTCP Deployment Models", draft-boucadair-mptcp- Assisted MPTCP Deployment Models", draft-boucadair-mptcp-
plain-mode-10 (work in progress), March 2017. plain-mode-10 (work in progress), March 2017.
[I-D.boucadair-radext-tcpm-converter] [I-D.boucadair-radext-tcpm-converter]
Boucadair, M. and C. Jacquenet, "RADIUS Extensions for Boucadair, M. and C. Jacquenet, "RADIUS Extensions for
0-RTT TCP Converters", draft-boucadair-radext-tcpm- 0-RTT TCP Converters", draft-boucadair-radext-tcpm-
converter-00 (work in progress), April 2018. converter-01 (work in progress), October 2018.
[I-D.boucadair-tcpm-dhc-converter] [I-D.boucadair-tcpm-dhc-converter]
Boucadair, M., Jacquenet, C., and R. K, "DHCP Options for Boucadair, M., Jacquenet, C., and R. K, "DHCP Options for
0-RTT TCP Converters", draft-boucadair-tcpm-dhc- 0-RTT TCP Converters", draft-boucadair-tcpm-dhc-
converter-00 (work in progress), April 2018. converter-01 (work in progress), October 2018.
[I-D.ietf-mptcp-rfc6824bis] [I-D.ietf-mptcp-rfc6824bis]
Ford, A., Raiciu, C., Handley, M., Bonaventure, O., and C. Ford, A., Raiciu, C., Handley, M., Bonaventure, O., and C.
Paasch, "TCP Extensions for Multipath Operation with Paasch, "TCP Extensions for Multipath Operation with
Multiple Addresses", draft-ietf-mptcp-rfc6824bis-12 (work Multiple Addresses", draft-ietf-mptcp-rfc6824bis-12 (work
in progress), October 2018. in progress), October 2018.
[I-D.ietf-tcpinc-tcpcrypt] [I-D.ietf-tcpinc-tcpcrypt]
Bittau, A., Giffin, D., Handley, M., Mazieres, D., Slack, Bittau, A., Giffin, D., Handley, M., Mazieres, D., Slack,
Q., and E. Smith, "Cryptographic protection of TCP Streams Q., and E. Smith, "Cryptographic protection of TCP Streams
(tcpcrypt)", draft-ietf-tcpinc-tcpcrypt-13 (work in (tcpcrypt)", draft-ietf-tcpinc-tcpcrypt-13 (work in
progress), September 2018. progress), September 2018.
[I-D.nam-mptcp-deployment-considerations]
Boucadair, M., Jacquenet, C., Bonaventure, O., Henderickx,
W., and R. Skog, "Network-Assisted MPTCP: Use Cases,
Deployment Scenarios and Operational Considerations",
draft-nam-mptcp-deployment-considerations-01 (work in
progress), December 2016.
[I-D.olteanu-intarea-socks-6] [I-D.olteanu-intarea-socks-6]
Olteanu, V. and D. Niculescu, "SOCKS Protocol Version 6", Olteanu, V. and D. Niculescu, "SOCKS Protocol Version 6",
draft-olteanu-intarea-socks-6-04 (work in progress), draft-olteanu-intarea-socks-6-04 (work in progress),
August 2018. August 2018.
[I-D.peirens-mptcp-transparent] [I-D.peirens-mptcp-transparent]
Peirens, B., Detal, G., Barre, S., and O. Bonaventure, Peirens, B., Detal, G., Barre, S., and O. Bonaventure,
"Link bonding with transparent Multipath TCP", draft- "Link bonding with transparent Multipath TCP", draft-
peirens-mptcp-transparent-00 (work in progress), July peirens-mptcp-transparent-00 (work in progress), July
2016. 2016.
skipping to change at page 34, line 24 skipping to change at page 35, line 33
[RFC1812] Baker, F., Ed., "Requirements for IP Version 4 Routers", [RFC1812] Baker, F., Ed., "Requirements for IP Version 4 Routers",
RFC 1812, DOI 10.17487/RFC1812, June 1995, RFC 1812, DOI 10.17487/RFC1812, June 1995,
<https://www.rfc-editor.org/info/rfc1812>. <https://www.rfc-editor.org/info/rfc1812>.
[RFC1919] Chatel, M., "Classical versus Transparent IP Proxies", [RFC1919] Chatel, M., "Classical versus Transparent IP Proxies",
RFC 1919, DOI 10.17487/RFC1919, March 1996, RFC 1919, DOI 10.17487/RFC1919, March 1996,
<https://www.rfc-editor.org/info/rfc1919>. <https://www.rfc-editor.org/info/rfc1919>.
[RFC1928] Leech, M., Ganis, M., Lee, Y., Kuris, R., Koblas, D., and [RFC1928] Leech, M., Ganis, M., Lee, Y., Kuris, R., Koblas, D., and
L. Jones, "SOCKS Protocol Version 5", RFC 1928, L. Jones, "SOCKS Protocol Version 5", RFC 1928,
DOI 10.17487/RFC1928, March 1996, <https://www.rfc- DOI 10.17487/RFC1928, March 1996,
editor.org/info/rfc1928>. <https://www.rfc-editor.org/info/rfc1928>.
[RFC2018] Mathis, M., Mahdavi, J., Floyd, S., and A. Romanow, "TCP [RFC2018] Mathis, M., Mahdavi, J., Floyd, S., and A. Romanow, "TCP
Selective Acknowledgment Options", RFC 2018, Selective Acknowledgment Options", RFC 2018,
DOI 10.17487/RFC2018, October 1996, <https://www.rfc- DOI 10.17487/RFC2018, October 1996,
editor.org/info/rfc2018>. <https://www.rfc-editor.org/info/rfc2018>.
[RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering: [RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering:
Defeating Denial of Service Attacks which employ IP Source Defeating Denial of Service Attacks which employ IP Source
Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827, Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827,
May 2000, <https://www.rfc-editor.org/info/rfc2827>. May 2000, <https://www.rfc-editor.org/info/rfc2827>.
[RFC3135] Border, J., Kojo, M., Griner, J., Montenegro, G., and Z. [RFC3135] Border, J., Kojo, M., Griner, J., Montenegro, G., and Z.
Shelby, "Performance Enhancing Proxies Intended to Shelby, "Performance Enhancing Proxies Intended to
Mitigate Link-Related Degradations", RFC 3135, Mitigate Link-Related Degradations", RFC 3135,
DOI 10.17487/RFC3135, June 2001, <https://www.rfc- DOI 10.17487/RFC3135, June 2001,
editor.org/info/rfc3135>. <https://www.rfc-editor.org/info/rfc3135>.
[RFC4787] Audet, F., Ed. and C. Jennings, "Network Address
Translation (NAT) Behavioral Requirements for Unicast
UDP", BCP 127, RFC 4787, DOI 10.17487/RFC4787, January
2007, <https://www.rfc-editor.org/info/rfc4787>.
[RFC6181] Bagnulo, M., "Threat Analysis for TCP Extensions for [RFC6181] Bagnulo, M., "Threat Analysis for TCP Extensions for
Multipath Operation with Multiple Addresses", RFC 6181, Multipath Operation with Multiple Addresses", RFC 6181,
DOI 10.17487/RFC6181, March 2011, <https://www.rfc- DOI 10.17487/RFC6181, March 2011,
editor.org/info/rfc6181>. <https://www.rfc-editor.org/info/rfc6181>.
[RFC6555] Wing, D. and A. Yourtchenko, "Happy Eyeballs: Success with
Dual-Stack Hosts", RFC 6555, DOI 10.17487/RFC6555, April
2012, <https://www.rfc-editor.org/info/rfc6555>.
[RFC6887] Wing, D., Ed., Cheshire, S., Boucadair, M., Penno, R., and [RFC6887] Wing, D., Ed., Cheshire, S., Boucadair, M., Penno, R., and
P. Selkirk, "Port Control Protocol (PCP)", RFC 6887, P. Selkirk, "Port Control Protocol (PCP)", RFC 6887,
DOI 10.17487/RFC6887, April 2013, <https://www.rfc- DOI 10.17487/RFC6887, April 2013,
editor.org/info/rfc6887>. <https://www.rfc-editor.org/info/rfc6887>.
[RFC6888] Perreault, S., Ed., Yamagata, I., Miyakawa, S., Nakagawa,
A., and H. Ashida, "Common Requirements for Carrier-Grade
NATs (CGNs)", BCP 127, RFC 6888, DOI 10.17487/RFC6888,
April 2013, <https://www.rfc-editor.org/info/rfc6888>.
[RFC6928] Chu, J., Dukkipati, N., Cheng, Y., and M. Mathis, [RFC6928] Chu, J., Dukkipati, N., Cheng, Y., and M. Mathis,
"Increasing TCP's Initial Window", RFC 6928, "Increasing TCP's Initial Window", RFC 6928,
DOI 10.17487/RFC6928, April 2013, <https://www.rfc- DOI 10.17487/RFC6928, April 2013,
editor.org/info/rfc6928>. <https://www.rfc-editor.org/info/rfc6928>.
[RFC6978] Touch, J., "A TCP Authentication Option Extension for NAT [RFC6978] Touch, J., "A TCP Authentication Option Extension for NAT
Traversal", RFC 6978, DOI 10.17487/RFC6978, July 2013, Traversal", RFC 6978, DOI 10.17487/RFC6978, July 2013,
<https://www.rfc-editor.org/info/rfc6978>. <https://www.rfc-editor.org/info/rfc6978>.
[RFC7323] Borman, D., Braden, B., Jacobson, V., and R. [RFC7323] Borman, D., Braden, B., Jacobson, V., and R.
Scheffenegger, Ed., "TCP Extensions for High Performance", Scheffenegger, Ed., "TCP Extensions for High Performance",
RFC 7323, DOI 10.17487/RFC7323, September 2014, RFC 7323, DOI 10.17487/RFC7323, September 2014,
<https://www.rfc-editor.org/info/rfc7323>. <https://www.rfc-editor.org/info/rfc7323>.
[RFC7414] Duke, M., Braden, R., Eddy, W., Blanton, E., and A. [RFC7414] Duke, M., Braden, R., Eddy, W., Blanton, E., and A.
Zimmermann, "A Roadmap for Transmission Control Protocol Zimmermann, "A Roadmap for Transmission Control Protocol
(TCP) Specification Documents", RFC 7414, (TCP) Specification Documents", RFC 7414,
DOI 10.17487/RFC7414, February 2015, <https://www.rfc- DOI 10.17487/RFC7414, February 2015,
editor.org/info/rfc7414>. <https://www.rfc-editor.org/info/rfc7414>.
[RFC8305] Schinazi, D. and T. Pauly, "Happy Eyeballs Version 2:
Better Connectivity Using Concurrency", RFC 8305,
DOI 10.17487/RFC8305, December 2017,
<https://www.rfc-editor.org/info/rfc8305>.
Appendix A. Differences with SOCKSv5 Appendix A. Differences with SOCKSv5
The description above is a simplified description of the Converter At a first glance, the Convert solution could seem similar to the
protocol. At a first glance, the proposed solution could seem SOCKS v5 protocol [RFC1928] which is used to proxy TCP connections.
similar to the SOCKS v5 protocol [RFC1928]. This protocol is used to The Client creates a connection to a SOCKS proxy, exchanges
proxy TCP connections. The Client creates a connection to a SOCKS authentication information and indicates the destination address and
proxy, exchanges authentication information and indicates the port of the final server. At this point, the SOCKS proxy creates a
destination address and port of the final server. At this point, the connection towards the final server and relays all data between the
SOCKS proxy creates a connection towards the final server and relays two proxied connections. The operation of an implementation based on
all data between the two proxied connections. The operation of an SOCKSv5 is illustrated in Figure 20.
implementation based on SOCKSv5 is illustrated in Figure 20.
Client SOCKS Proxy Server Client SOCKS Proxy Server
--------------------> -------------------->
SYN SYN
<-------------------- <--------------------
SYN+ACK SYN+ACK
--------------------> -------------------->
ACK ACK
--------------------> -------------------->
skipping to change at page 37, line 23 skipping to change at page 38, line 34
extension. Neither SOCKS v5 [RFC1928] nor the proposed SOCKS v6 extension. Neither SOCKS v5 [RFC1928] nor the proposed SOCKS v6
[I-D.olteanu-intarea-socks-6] provide such a feature. [I-D.olteanu-intarea-socks-6] provide such a feature.
A third difference is that a Transport Converter will only accept the A third difference is that a Transport Converter will only accept the
connection initiated by the Client provided that the downstream connection initiated by the Client provided that the downstream
connection is accepted by the Server. If the Server refuses the connection is accepted by the Server. If the Server refuses the
connection establishment attempt from the Transport Converter, then connection establishment attempt from the Transport Converter, then
the upstream connection from the Client is rejected as well. This the upstream connection from the Client is rejected as well. This
feature is important for applications that check the availability of feature is important for applications that check the availability of
a Server or use the time to connect as a hint on the selection of a a Server or use the time to connect as a hint on the selection of a
Server [RFC6555]. Server [RFC8305].
Authors' Addresses Authors' Addresses
Olivier Bonaventure (editor) Olivier Bonaventure (editor)
Tessares Tessares
Email: Olivier.Bonaventure@tessares.net Email: Olivier.Bonaventure@tessares.net
Mohamed Boucadair (editor) Mohamed Boucadair (editor)
Orange Orange
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