Internet DRAFT - draft-abdo-hostid-tcpopt-implementation
draft-abdo-hostid-tcpopt-implementation
Network Working Group E. Abdo
Internet-Draft M. Boucadair
Intended status: Informational J. Queiroz
Expires: January 17, 2013 France Telecom
July 16, 2012
HOST_ID TCP Options: Implementation & Preliminary Test Results
draft-abdo-hostid-tcpopt-implementation-03
Abstract
This memo documents the implementation of the HOST_ID TCP Options.
It also discusses the preliminary results of the tests that have been
conducted to assess the technical feasibility of the approach as well
as its scalability. Several HOST_ID TCP options have been
implemented and tested.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on January 17, 2013.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. NAT Reveal TCP Options: Overview . . . . . . . . . . . . . . . 5
3.1. HOST_ID_WING TCP Option . . . . . . . . . . . . . . . . . 5
3.2. HOST_ID_BOUCADAIR TCP Option . . . . . . . . . . . . . . . 5
3.2.1. SYN Mode . . . . . . . . . . . . . . . . . . . . . . . 6
3.2.2. ACK Mode . . . . . . . . . . . . . . . . . . . . . . . 7
4. Overview of the Linux Kernel Modifications . . . . . . . . . . 7
5. Testbed Setup & Configuration . . . . . . . . . . . . . . . . 8
5.1. Automated TCP Traffic Generator . . . . . . . . . . . . . 10
5.2. Testing Methodology and Procedure . . . . . . . . . . . . 10
5.3. Check HOST_ID TCP Options are Correctly Injected . . . . . 11
5.4. Top Site List . . . . . . . . . . . . . . . . . . . . . . 11
6. Experimentation Results . . . . . . . . . . . . . . . . . . . 11
6.1. HTTP Experimentation Results . . . . . . . . . . . . . . . 11
6.1.1. Configuration 1: Connected to an enterprise network . 12
6.1.1.1. Results . . . . . . . . . . . . . . . . . . . . . 12
6.1.1.2. Analysis . . . . . . . . . . . . . . . . . . . . . 14
6.1.2. Configuration 2: In a lab behind a firewall . . . . . 15
6.1.3. Configuration 3: Connected to two commercial ISP
networks . . . . . . . . . . . . . . . . . . . . . . . 15
6.1.4. Additional Results . . . . . . . . . . . . . . . . . . 16
6.1.5. Analysis . . . . . . . . . . . . . . . . . . . . . . . 16
6.2. FTP . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6.3. SSH . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.4. Telnet . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7. AFTR Module Modifications . . . . . . . . . . . . . . . . . . 19
7.1. Specification . . . . . . . . . . . . . . . . . . . . . . 19
7.2. Verification . . . . . . . . . . . . . . . . . . . . . . . 20
7.3. CGN Performance Testing . . . . . . . . . . . . . . . . . 21
7.3.1. Configuration . . . . . . . . . . . . . . . . . . . . 21
7.3.2. HTTP Testing . . . . . . . . . . . . . . . . . . . . . 22
7.3.2.1. Analysis of results . . . . . . . . . . . . . . . 24
7.3.2.2. Conclusion . . . . . . . . . . . . . . . . . . . . 24
7.3.3. FTP . . . . . . . . . . . . . . . . . . . . . . . . . 25
8. IPTABLES: Modifications to Enforce Policies at the Server
Side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
8.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 25
8.2. Validation . . . . . . . . . . . . . . . . . . . . . . . . 26
8.3. Stripping HOST_ID Options . . . . . . . . . . . . . . . . 26
8.4. Logging a Specific HOST_ID Option Value . . . . . . . . . 27
8.5. Dropping a specific HOST_ID Option Value . . . . . . . . . 28
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29
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10. Security Considerations . . . . . . . . . . . . . . . . . . . 29
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 29
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 29
12.1. Normative References . . . . . . . . . . . . . . . . . . . 29
12.2. Informative References . . . . . . . . . . . . . . . . . . 29
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 30
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1. Introduction
To ensure IPv4 service continuity, service providers will need to
deploy IPv4 address sharing techniques. Several issues are likely to
be encountered (refer to [RFC6269] for a detailed survey of the
issues) and they may affect the delivery of services that depends on
the enforcement of policies based upon the source IPv4 address.
Some of these issues may be mitigated owing to the activation of
advanced features. Among the solutions analyzed in
[I-D.boucadair-intarea-nat-reveal-analysis], the use of a new TCP
option to convey a HOST_ID seems to be a promising solution.
This memo documents some implementation and experimentation efforts
that have been conducted to assess the viability of using HOST_ID TCP
options at large scale. In particular, this document provides
experimentation results related to the support of the HOST_ID TCP
Options, the behavior of legacy TCP servers when receiving the
HOST_ID TCP options. This draft also discusses the impact of using a
HOST_ID TCP options on the time it takes to establish a connection;
it also tries to evaluate the impact of the new TCP options on the
performance of the CGN. Finally it presents the enforcement policies
that could be applied by remote servers based upon the HOST_ID
options contents.
2. Objectives
The implementation of several HOST_ID TCP options is primarily meant
to:
o Assess the validity of the HOST_ID TCP option approach
o Evaluate the impact on the TCP stack to support the HOST_ID TCP
options
o Improve filtering and logging capabilities based upon the contents
of the HOST_ID TCP option. This means the enforcement of various
policies based upon the content of the HOST_ID TCP option at the
server side: Log, Deny, Accept, etc.
o Assess the behavior of legacy TCP servers when receiving a HOST_ID
TCP option
o Assess the success ratio of TCP communications when a HOST_ID TCP
option is received
o Assess the impact of injecting a HOST_ID TCP option on the time it
takes to establish a connection
o Assess the performance impact on the CGN device that has been
configured to inject the HOST_ID option
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3. NAT Reveal TCP Options: Overview
The original idea of defining a TCP option is documented in
[I-D.wing-nat-reveal-option] and denoted as HOST_ID_WING.
An additional TCP option is also considered and denoted as
HOST_ID_BOUCADAIR. The main motivation is to cover also the load-
balancer use case and provide richer functionality as Forwarded-For
HTTP header than HOST_ID_WING can provide.
The following sub-sections provide an overview of these HOST_ID TCP
options.
3.1. HOST_ID_WING TCP Option
HOST_ID_WING is defined in [I-D.wing-nat-reveal-option]. Figure 1
shows the format of this option.
+--------+--------+-----------------------+
|Kind=TBD|Length=4| HOST_ID Data |
+--------+--------+-----------------------+
Figure 1: Format of HOST_ID_WING TCP Option
This option must be sent only upon the initial connection request,
i.e., in SYN packets as shown in Figure 2
+------------+ +------------+ +------------+
| TCP CLIENT | | CGN | | TCP SERVER |
+------------+ +------------+ +------------+
| | |
|---TCP SYN---------->| |
| |---TCP SYN, HOST_ID=12345---->|
| | |
Figure 2: HOST_ID_WING TCP Option: Flow example
3.2. HOST_ID_BOUCADAIR TCP Option
As mentioned above, the HOST_ID_BOUCADAIR TCP Option is inspired from
HOST_ID_WING and XFF.
The HOST_ID_BOUCADAIR option is a 10-byte long TCP option, where
KIND, Length and lifetime-Origin fields fill one byte each, and
HOST_ID data is 7-byte long as shown in Figure 3
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+--------+---------+---+---+--------..-------+
|Kind=TBD|Length=10| L | O | HOST_ID_data | HOST_ID
+--------+---------+---+---+--------..-------+
Figure 3: Format of HOST_ID_BOUCADAIR TCP option
o L: Indicates the validity lifetime of the enclosed data (in the
spirit of [RFC6250]). The following values are supported:
0: Permanent;
>0:Dynamic; this value indicates the validity time.
o Origin: Indicates the origin of the data conveyed in the data
field. The following values are supported:
0: Internal Port
1: Internal IPv4 address
2: Internal Port: Internal IPv4 address
3: IPv6 Prefix
>3: No particular semantic
o HOST_ID_data depends on the content of the Origin field; padding
is required.
Two modes are described below: the SYN mode (Section 3.2.1) and the
ACK mode. (Section 3.2.2).
If the ACK mode is used (Section 3.2.2), Figure 4 shows the
HOST_ID_ENABLED option (2-bytes long) to be included in the SYN.
+--------+---------+
|Kind=TBD|Length=2 | HOST_ID_ENABLED
+--------+---------+
Figure 4: Format of HOST_ID_ENABLED
3.2.1. SYN Mode
This mode is similar to the mode described in Section 3.1. In this
mode, HOST_ID_BOUCADAIR is sent in SYN packets.
+------------+ +------------+ +------------+
| TCP CLIENT | | CGN | | TCP SERVER |
+------------+ +------------+ +------------+
| | |
|---TCP SYN-------->| |
| |--TCP SYN, HOST_ID=2001:db8::/5482->|
| | |
Figure 5: HOST_ID_BOUCADAIR: SYN Mode
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3.2.2. ACK Mode
The ACK Mode is as follows (see Figure 6):
o Send HOST_ID_ENABLED (Figure 4) in SYN
o If the remote TCP server supports that option, it must return it
in SYNACK
o Then the TCP Client sends an ACK in which the CGN injects
HOST_ID_BOUCADAIR (Figure 3)
+------------+ +------------+ +------------+
| TCP CLIENT | | CGN | | TCP SERVER |
+------------+ +------------+ +------------+
| | |
|---TCP SYN---------->| |
| |--TCP SYN, HOSTID_ENABLED=OK-->|
| |<-TCP SYNACK,HOSTID_ENABLED=OK-|
|<--TCP SYNACK--------| |
|---TCP ACK---------->| |
| |--TCP ACK, HOST_ID=2001:db8::->|
| | |
Figure 6: HOST_ID_BOUCADAIR: ACK Mode
4. Overview of the Linux Kernel Modifications
The objective of this phase is to support HOST_ID_WING,
HOST_ID_BOUCADAIR and HOST_ID_ENABLED in the SYN mode.
In order to support the injection of the HOST_ID TCP options
presented in Section 3, some modifications were applied to the Linux
Kernel (more precisely to the TCP stack part of the Kernel). The
header file tcp.h, file where are defined the TCP variables and
functions, is updated to define the new HOST_ID options' KINDs
(option numbers) and Lengths.
Major modifications have been made in the "tcp_output.c" file. This
file is responsible for building and transmitting all TCP packets.
For each HOST_ID TCP option, the required modifications to increase
the header size and to inject KIND, Length and the corresponding
HOST_ID data are implemented for the TCP SYN packets.
As we have three different HOST_ID options and as HOST_ID_BOUCADAIR
can convey different information the configuration of the HOST_ID
options have to be simple with minimal complexity. Since the
manipulation of HOST_ID options impacts the Kernel TCP drivers, a
suitable solution is to define new sysctl variables (system control
variables) that allow the modification of Kernel parameters at
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runtime, without having to reboot the machine so that it takes into
account a new configuration.
Once modifications have taken place, the Kernel must be recompiled so
that the new TCP options are taken into account.
Kernel modifications and recompilation have been done and tested
successfully on Fedora and Debian Linux distributions, on different
kernel versions.
The following configuration options are supported:
o Enable/Disable injecting the TCP Option
o Support HOST_ID WING, HOST_ID BOUCADAIR and HOST_ID_ENABLED
o When the HOST_ID TCP option is supported, the information to be
injected is configurable:
* Source IPv6 address or the first 56 bits of the address
* Source IPv4 address
* Source port number
* Source IPv4 address and Source port
* IPv6 address or the first 56 bits of the B4 when DS-Lite is
activated
5. Testbed Setup & Configuration
The setup of three testbed configurations have been considered:
1. HOST_ID TCP option is injected by the host itself. No CGN is
present in the forwarding path (Figure 7)
2. HOST_ID TCP option is injected by hosts deployed behind a HTTP
proxy. No CGN is present in the forwarding path (Figure 8)
3. HOST_ID TCP option is injected by the DS-Lite AFTR element
(Figure 9).
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+-----------+
| HOST_1 |----+
| NO-Option | |
+-----------+ | +--------------------+ +------------+
| | |--------| server 1 |
+-----------+ | | | +------------+
| HOST_2 |----|------| INTERNET | :::
| (HOST_ID) | | | | +------------+
+-----------+ | | |--------| server n |
| +--------------------+ +------------+
+-----------+ |
| Local |----+
| Server |
+-----------+
Figure 7: Testbed setup: No Proxy and no CGN
+-----------+
| HOST_1 |----+
| NO-Option | |
+-----------+ | +--------------------+ +------------+
| | |------| server 1 |
+-----------+ +-----+ | | +------------+
| HOST_2 |--|PROXY|----| INTERNET | ::
| (HOST_ID) | +-----+ | | | +------------+
+-----------+ | | |------| server n |
| +--------------------+ +------------+
+-----------+ |
| Local |-----------+
| Server |
+-----------+
Figure 8: Testbed setup: HTTP Proxy
+----...----+ +----------+
+----+ | | | |---| server 1 |
|HOST|---| +----+ | +------+ | | | +----------+
+----+ |--| B4 |---|---| AFTR |---|---| INTERNET | ::
+----+ | +------+ | | | +----------+
| | |---| server n |
+----...----+ +----------+
Figure 9: DS-Lite CGN Environment
Figure 7 and Figure 8 are used to assess the behavior of the top
100,000 sites when a HOST_ID option is enabled and to evaluate the
impact of the option on both the session establishment delay and the
success ratio.
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On the other hand, the configuration shown in Figure 9 will be used
to evaluate the impact on the CGN performances when HOST_ID TCP
option is injected by the CGN.
5.1. Automated TCP Traffic Generator
A Python-encoded robot has been used as the traffic generator. The
robot automates the retrieval of HTTP pages identified by URLs, and
returns different connection information. The retrieval of pages is
based upon Pycurl, a Python interface of libcurl. Libcurl is an URL
transfer library that supports different protocols (e.g., HTTP, FTP).
The robot consists of two programs:
1. The first one takes an URL as a input parameter, performs the DNS
lookup and then tries to connect to the corresponding machine.
It returns either different time values and connection status or
an error message with the source of the error in case of
connection failure (e.g., DNS error). The TCP connection
establishment time is calculated as the difference between the
CONNECT_TIME and NAMELOOKUP_TIME where:
* NAMELOOKUP_TIME is the time it took from the start until the
name resolution is completed.
* CONNECT_TIME is the time it took from the start until the
connection to the remote host (or proxy) is completed.
2. The second program aims to increase efficiency and speed of the
testing by using a multi-thread technique. It takes the number
of threads and an input file listing URLs as parameters. This
program prints URLs to an output file with the corresponding
connection time. If something wrong happened so that the
connection failed, the program returns an error message with the
corresponding error type.
5.2. Testing Methodology and Procedure
The testing is done using two machines, one that supports the HOST_ID
TCP options and the other that does not. The second machine is used
as a reference for the measurements. Testing is performed in
parallel on the two machines that are directly connected to the
Internet. For each HOST_ID TCP option, the test is repeated many
times. The cycle is repeated in different days. Then results are
grouped into tables where averages are calculated. The comparison
between the different HOST_ID options results is made by using the
no-option testing results as a reference.
Testing was also performed behind a proxy (Figure 8) to evaluate the
impact of embedding the HOST_ID TCP options on the connection
establishment time when a proxy is in the path. When a proxy is
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present, the connection delay is impacted (the delay is calculated
for the connection between the host and the proxy).
Tests have been conducted from hosts:
1. Connected to an enterprise network
2. In a lab behind a firewall
3. Connected to two (2) commercial ISP networks
5.3. Check HOST_ID TCP Options are Correctly Injected
To check whether the HOST_ID TCP options are correctly injected, the
local server in Figure 7 is configured to be reachable from Internet.
Packets conveying the HOST_ID TCP options are sent from a host
supporting the options. These packets are used without alteration by
the local server.
This configuration confirms the packets sent to remote servers
conveys HOST_ID TCP options.
5.4. Top Site List
The Alexa top sites list has been used to conduct the HTTP tests.
Anonymous FTP sites list from ftp-sites.org has been used to conduct
the FTP tests.
6. Experimentation Results
Various combinations of the HOST_ID TCP options have been tested:
1. HOST_ID_WING
2. HOST_ID_WING has also been adapted to include 32 bits and 64 bits
values. No particular impact on session establishment has been
observed.
3. HOST_ID_BOUCADAIR (source port)
4. HOST_ID_BOUCADAIR (IPv4 address)
5. HOST_ID_BOUCADAIR (source port:IPv4 address)
6. HOST_ID_BOUCADAIR (IPv6 Prefix)
7. HOST_ID_ENABLED
Both the success ratio and the average time to establish the TCP
session are reported below.
6.1. HTTP Experimentation Results
Tests have been conducted from hosts:
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1. Connected to an enterprise network
2. Connected to two commercial ISP networks
3. In a lab behind a firewall
6.1.1. Configuration 1: Connected to an enterprise network
The results show that the success ratio for establishing TCP
connection with legacy servers is almost the same for all the HOST_ID
options as shown in Figure 10, Figure 11 and Figure 12.
6.1.1.1. Results
+--------------+--------------+--------------+
| NO-OPTION | O-WING | Failure Ratio|
-----------+--------------+--------------+--------------+
Top10 | 100,00000% | 100,00000% | 0,00000% |
Top100 | 100,00000% | 100,00000% | 0,00000% |
Top200 | 100,00000% | 100,00000% | 0,00000% |
Top300 | 99,66667% | 99,66667% | 0,00000% |
Top400 | 99,50000% | 99,50000% | 0,00000% |
Top500 | 99,40000% | 99,40000% | 0,00000% |
Top600 | 99,50000% | 99,50000% | 0,00000% |
Top700 | 99,57143% | 99,57143% | 0,00000% |
Top800 | 99,50000% | 99,50000% | 0,00000% |
Top900 | 99,44444% | 99,44444% | 0,00000% |
Top1000 | 99,50000% | 99,50000% | 0,00000% |
Top2000 | 99,35000% | 99,30000% | 0,05000% |
Top3000 | 99,10000% | 99,06667% | 0,03333% |
Top4000 | 99,10000% | 99,05000% | 0,05000% |
Top5000 | 99,14000% | 99,10000% | 0,04000% |
Top6000 | 99,21667% | 99,18333% | 0,03333% |
Top7000 | 99,25714% | 99,21429% | 0,04286% |
Top8000 | 99,15000% | 99,10000% | 0,05000% |
Top9000 | 99,16667% | 99,12222% | 0,04444% |
Top10000 | 99,16000% | 99,12000% | 0,04000% |
Top20000 | 98,50500% | 98,44000% | 0,06500% |
Top30000 | 98,21667% | 98,11667% | 0,10000% |
Top40000 | 98,10750% | 98,00750% | 0,10000% |
Top50000 | 98,00000% | 97,89800% | 0,10200% |
Top60000 | 97,95167% | 97,85000% | 0,10167% |
Top70000 | 97,88857% | 97,78857% | 0,10000% |
Top80000 | 97,84500% | 97,74875% | 0,09625% |
Top90000 | 97,79444% | 97,69889% | 0,09556% |
Top100000 | 97,75100% | 97,64800% | 0,10300% |
-----------+--------------+--------------+--------------+
Figure 10: Cumulated Success ratio (HOST_ID_WING)
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+-----------+-----------+--------------+
| NO-OPTION | O-WING | Failure Ratio|
-------------+-----------+-----------+--------------+
1-100 | 100,00% | 100,00% | 0,00% |
101-200 | 100,00% | 100,00% | 0,00% |
201-300 | 99,00% | 99,00% | 0,00% |
301-400 | 99,00% | 99,00% | 0,00% |
401-500 | 99,00% | 99,00% | 0,00% |
501-600 | 100,00% | 100,00% | 0,00% |
601-700 | 100,00% | 100,00% | 0,00% |
701-800 | 99,00% | 99,00% | 0,00% |
801-900 | 99,00% | 99,00% | 0,00% |
901-1000 | 100,00% | 100,00% | 0,00% |
1-1000 | 99,50% | 99,50% | 0,00% |
1001-2000 | 99,20% | 99,10% | 0,10% |
2001-3000 | 98,60% | 98,60% | 0,00% |
3001-4000 | 99,10% | 99,00% | 0,10% |
4001-5000 | 99,30% | 99,30% | 0,00% |
5001-6000 | 99,60% | 99,60% | 0,00% |
6001-7000 | 99,50% | 99,40% | 0,10% |
7001-8000 | 98,40% | 98,30% | 0,10% |
8001-9000 | 99,30% | 99,30% | 0,00% |
9001-10000 | 99,10% | 99,10% | 0,00% |
10001-20000 | 97,85% | 97,76% | 0,90% |
20001-30000 | 97,64% | 97,47% | 1,70% |
30001-40000 | 97,78% | 97,68% | 1,00% |
40001-50000 | 97,57% | 97,46% | 1,10% |
50001-60000 | 97,71% | 97,61% | 1,00% |
60001-70000 | 97,61% | 97,52% | 0,90% |
70001-80000 | 97,44% | 97,37% | 0,70% |
80001-90000 | 97,39% | 97,30% | 0,90% |
90001-100000 | 97,36% | 97,19% | 1,70% |
-------------+-----------+-----------+--------------+
Figure 11: TopX000 Success Ratio (HOST_ID_WING)
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+-----------+-----------+--------------+
| NO-OPTION |O-BOUCADAIR| Failure Ratio|
-------------+-----------+-----------+--------------+
1-100 | 100,00% | 100,00% | 0,00% |
101-200 | 100,00% | 100,00% | 0,00% |
201-300 | 99,00% | 99,00% | 0,00% |
301-400 | 99,00% | 99,00% | 0,00% |
401-500 | 99,00% | 99,00% | 0,00% |
501-600 | 100,00% | 100,00% | 0,00% |
601-700 | 100,00% | 100,00% | 0,00% |
701-800 | 99,00% | 99,00% | 0,00% |
801-900 | 99,00% | 99,00% | 0,00% |
901-1000 | 100,00% | 100,00% | 0,00% |
0-1000 | 99,50% | 99,50% | 0,00% |
1001-2000 | 99,20% | 99,10% | 0,10% |
2001-3000 | 98,60% | 98,60% | 0,00% |
3001-4000 | 99,30% | 99,30% | 0,00% |
5001-6000 | 99,60% | 99,60% | 0,00% |
6001-7000 | 99,50% | 99,40% | 0,10% |
7001-8000 | 98,40% | 98,30% | 0,10% |
8001-9000 | 99,30% | 99,20% | 0,10% |
9001-10000 | 99,10% | 99,10% | 0,00% |
10001-20000 | 97,85% | 97,76% | 0,90% |
20001-30000 | 97,64% | 97,46% | 1,80% |
30001-40000 | 97,78% | 97,66% | 1,20% |
40001-50000 | 97,57% | 97,46% | 1,10% |
50001-60000 | 97,71% | 97,61% | 1,00% |
60001-70000 | 97,61% | 97,51% | 1,00% |
70001-80000 | 97,44% | 97,36% | 0,80% |
80001-90000 | 97,39% | 97,30% | 0,90% |
90001-100000 | 97,36% | 97,19% | 1,70% |
-------------+-----------+-----------+--------------+
Figure 12: TopX000 Success Ratio (HOST_ID_BOUCADAIR)
6.1.1.2. Analysis
o For the top 100,000 sites, connection failures occur for 2249 HTTP
sites. These failures were reported as being caused by DNS issues
(servers not mounted), connection timeouts (servers down...),
connection resets by peers, connection problems and empty replies
from servers. The 2249 failures occur, whether HOST_ID options
are injected or not.
o When any HOST_ID TCP option is conveyed, 103 servers did not
respond; however when no option is injected, all these servers
responded normally.
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o Same results were obtained for HOST_ID_WING and HOST_ID_ENABLED.
o Same results were obtained for all the HOST_ID_BOUCADAIR options
(source port, IPv6 prefix, etc.).
When HOST_ID_BOUCADAIR is enabled, six (6) additional servers did not
respond:
o Three (3) servers (www.teufel.de - www.1001fonts.com - www.sigur-
ros.co.uk) did not respond to the SYN packets sent by the host.
o Three (3) servers (www.lawyers.com, www.lexis.com, www.nexis.com)
responded with "strange" SYN/ACK packets with same TCP options
length including a part of the HOST_ID options that was sent.
This part of HOST_ID option caused an erroneous SYN/ACK packet
received by the host: in fact the second byte of the HOST_ID part
is considered as its length and this length does not really fit
with the real length of the part. So the machine does not respond
back to the server with an ACK packet. This is why we have no
response for these servers.
When HOST_ID_WING or HOST_ID_ENABLED is enabled, also strange SYN/
ACKs were received by the host but no errors in these packets (a long
series of NOP options). This justifies the connection success for
these 2 options.
The results show that including a HOST_ID TCP option does not
systematically imply an extra delay for the establishment of the TCP
session. Based on the average of session establishment with the top
100 000 sites, the following results have been obtained:
o delay(HOST_ID_WING) < delay(NO_OPTION): 42,55 %
o delay(HOST_ID_BOUCADAIR ) < delay(NO_OPTION): 48,16 %
o delay(HOST_ID_ENABLED) < delay(NO_OPTION): 51,28 %
6.1.2. Configuration 2: In a lab behind a firewall
When a HTTP proxy is in the path, the injection of HOST_ID TCP option
does not impact the success ratio. This is due to that the HTTP
proxy strips the HOST_ID TCP options; these options are not leaked to
remote Internet servers. The testing has been done by observing
packets received to a server installed with a public IP address (no
HOST_ID options were seen in the received SYN packets).
6.1.3. Configuration 3: Connected to two commercial ISP networks
The results obtained when testing was performed by connecting to two
ISP networks confirmed the results obtained in the testing described
in Section 6.1.1
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6.1.4. Additional Results
In one of our testing for top 1000 sites, when padding was badly
implemented for HOST_ID_BOUCADAIR (padding was implemented as a
prefix so option's Length does not correspond to the real length
because the padding was not counted), we got for configuration(1) in
the lab and for one of the ISP the following results:
+-------------+-------------+--------------+
| No-Option | O-BOUCADAIR | Failure Ratio|
--------+-------------+-------------+--------------+
Top10 | 100,00000% | 100,00000% | 0,00000% |
Top100 | 100,00000% | 100,00000% | 0,00000% |
Top200 | 100,00000% | 100,00000% | 0,00000% |
Top300 | 100,00000% | 99,66667% | 0,33333% |
Top400 | 99,75000% | 99,00000% | 0,75000% |
Top500 | 99,80000% | 99,00000% | 0,80000% |
Top600 | 99,83333% | 98,66667% | 1,16667% |
Top700 | 99,85714% | 98,14286% | 1,71429% |
Top800 | 99,75000% | 98,00000% | 1,75000% |
Top900 | 99.66667% | 97,33333% | 2,33333% |
Top1000 | 99,70000% | 97,10000% | 2,60000% |
--------+-------------+-------------+--------------+
Cumulated Success ratio (HOST_ID_Boucadair with wrong padding)
The results for HOST_ID_WING for all three configurations are the
same as Section 6 (this option was correctly coded). Results
obtained for HOST_ID_BOUCADAIR are not the same.
For the configuration (2) behind a firewall, we did not face any
rejection because of parsing the TCP options (the HOST_ID options
were retrieved from the packet).
6.1.5. Analysis
Configuration (1) in Lab and for one of the two CPEs lead to the
results because 2.6% of these 1000 servers perform parsing validation
for the received options so when the bad HOST_ID_BOUCADAIR option is
sent, 2.6% of the servers treat the received SYN packets as erroneous
packets and discard them.
For the connection behind the second ISP, we didn't get a response
for any of the servers. After investigation, the reason was that the
Box validates the received packets before sending them to the
Internet. The erroneous SYN packets holding badly encoded options
(HOST_ID_BOUCADAIR in this case) were dropped and no connection was
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established. On the other hand, the other box did not validate
options length for received packets before sending them to the
Internet.
6.2. FTP
Various combinations of the HOST_ID TCP options have been tested:
1. HOST_ID_WING
2. HOST_ID_BOUCADAIR (source port)
3. HOST_ID_BOUCADAIR (source port:IPv4 address)
A list of 5591 FTP servers has been used to conduct these testings.
Among this list, only 2045 were reachable:
o Failure to reach 942 FTP servers due to connection timeout
o Failure to reach 1286 FTP servers due to DNS errors
o Failure to reach 717 FTP servers because access was denied
o Could not connect to 500 FTP servers
o Response reading failed for 81 servers
o Bad response from server for 20 servers
When HOST_ID TCP options are injected, 9 errors are observed
(connection timeout).
Figure 13 and Figure 14 provide more data about the error
distribution.
+-----------+-----------+--------------+
| NOB | HOST_ID | Failure Ratio|
-----------+-----------+-----------+--------------+
1-100 | 100% | 100% | 0,000% |
101-200 | 100% | 99% | 1,000% |
201-300 | 100% | 99% | 1,000% |
301-400 | 100% | 100% | 0,000% |
401-500 | 100% | 100% | 0,000% |
501-600 | 100% | 100% | 0,000% |
601-700 | 100% | 100% | 0,000% |
701-800 | 100% | 100% | 0,000% |
801-900 | 100% | 99% | 1,000% |
901-1000 | 100% | 99% | 1,000% |
1001-2000 | 100% | 99,5% | 0,500% |
2000-2045 | 100% | 100% | 0,000% |
-----------+-----------+-----------+--------------+
Figure 13: Cumulated Success Ratio (FTP)
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+-----------+-----------+--------------+
| NOB | HOST_ID | Failure Ratio|
----------+-----------+-----------+--------------+
first 10 | 100,000% | 100,000% | 0,000% |
first 100 | 100,000% | 100,000% | 0,000% |
first 200 | 100,000% | 99,500% | 0,500% |
first 300 | 100,000% | 99,333% | 0,667% |
first 400 | 100,000% | 99,500% | 0,500% |
first 500 | 100,000% | 99,600% | 0,400% |
first 600 | 100,000% | 99,667% | 0,333% |
first 700 | 100,000% | 99,714% | 0,286% |
first 800 | 100,000% | 99,750% | 0,250% |
first 900 | 100,000% | 99,667% | 0,333% |
first 1000| 100,000% | 99,600% | 0,400% |
first 2000| 100,000% | 99,550% | 0,450% |
first 2045| 100,000% | 99,560% | 0,440% |
----------+-----------+-----------+--------------+
Figure 14: FirstXXX FTP Servers
The results show that including a HOST_ID TCP option does not
systematically imply an extra delay for the establishment of the TCP
session with remote FTP servers. Based upon the average of the
session establishment with the 2045 FTP sites, the following results
have been obtained:
o delay(HOST_ID_WING) < delay(NO_OPTION): 49,36585 %
o delay(HOST_ID_BOUCADAIR (source port:IPv4 address)) <
delay(NO_OPTION): 48,41076%
o delay(HOST_ID_BOUCADAIR (source port)) < delay(NO_OPTION):
48,43902 %
6.3. SSH
The secure shell service has been tested between a host and a SSH
server connected to the same network.
SSH connections have been successfully established with the server
for all the HOST_ID TCP options. Same results were obtained using
configuration (1) and configuration (2).
6.4. Telnet
Telnet sessions have been successfully initiated for all HOST_ID TCP
options with a server (the CGN used in Figure 9).
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7. AFTR Module Modifications
This section highlights the support the HOST_ID functionalities in
the AFTR element of the DS-Lite model (Figure 9) and presents the
testing results in order to conclude about the HOST_ID TCP options
impacts on the performance of the CGN.
We used ISC AFTR implementation.
7.1. Specification
All privately-addressed IPv4 packets sent from DS-Lite serviced hosts
go through an AFTR device where an isc_aftr daemon program is
responsible for establishing the tunnel, configuring network
interfaces and processing received packets.
The aftr.c source code controls all functionalities to be included or
modified on packets received by the CGN, e.g., patching TCP MSS
values, fix MTU, etc.
In order to activate/deactivate such functionalities, the
corresponding parameters can be configured in a specific
configuration file called "aftr.conf". In this file, other
parameters are configured, e.g., the IPv6 addresses assigned to the
tunnel endpoint and the global IPv4 address pool maintained by the
CGN.
To support the injection of HOST_ID TCP options, "aftr.c" must be
updated to inject, retrieve or verify the HOST_ID options depending
on the HOST_ID parameters defined in "aftr.conf" file. Four HOST_ID
parameters are defined in the configuration file:
1. hostid: to enable the injection, retrieval, matching... of
HOST_ID options
2. hostid_wing: to enable injection/verification of HOST_ID_WING -
to disable injection or to remove HOST_ID_WING
3. hostid_boucadair: to enable injection/verification of
HOST_ID_BOUCADAIR - to disable injection or to remove
HOST_ID_BOUCADAIR
4. hostid_enabled: to enable or disable HOST_ID_ENABLED injection
hostid, hostid_wing and hostid_enabled can be simply enabled or
disabled. hostid_boucadair can be disabled or enabled with the
corresponding Origin as HOST_ID data can be:
o Source Port Number
o Source IPv4 Address
o Source IPv4 Address + Source Port Number
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o 56 bits of Tunnel Softwire IPv6 Source Address.
Based on different HOST_ID parameters, the "aftr.c" code has been
modified to control HOST_ID options; the AFTR is able to:
o Inject the enabled HOST_ID TCP option if it is not already present
in the packet
o Retrieve an existing HOST_ID TCP option if this option is not
enabled
o Check an existing HOST_ID option's content if it is enabled; if
the content's verification failed, the AFTR replaces the HOST_ID
contents with the suitable information
The implementation takes into consideration the SYN mode for all the
HOST_ID options (even for HOST_ID_enabled). The Support of
HOST_ID_BOUCADAIR in the ACK mode needs implementation on the
server's side and since both Enabled and Boucadair's options have
been tested and no impact observed; the ACK mode should not imply any
complication in implementation or impact on the performance.
7.2. Verification
The verification of HOST_ID implementation in the CGN has taken place
using the testbed setup shown in Figure 9. The host used in this
testing is a modified Linux machine that can inject HOST_ID options.
The objective of the testing is to verify the different
functionalities implemented in the AFTR. Verification has occurred
using a local server where all the received packets were observed to
make sure that the content of the HOST_ID fields is consistent with
the enabled option.
The testing consists in observing the SYN packets (as SYN mode is
supported) sent by the host and in comparing these packets to those
received by the server. Different combinations of HOST_ID options
sent by the host and HOST_ID configured options at the CGN level have
been used.
The results show that once the host sends packets without any HOST_ID
option injected, the SYN packets received by the server contain the
correct option that has been enabled by the CGN (if any). Once
HOST_ID_WING or HOST_ID_BOUCADAIR are injected by the host, if the
hostid parameter in aftr.conf is enabled, the enabled (in
"aftr.conf") HOST_ID option will be injected if not already present,
or else its content will be verified and corrected (if wrong); the
other disabled option will be discarded if it has already been sent
by the host.
One additional case has been tested when both Wing's and Boucadair's
HOST_ID options are sent by the host, the contents of the enabled
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option are checked and corrected (if wrong), the other option is
retrieved from the packet. The two options are dropped from the
packet if they are both disabled.
The testing has been repeated for all the HOST_ID options sent by the
host and enabled by the CGN. Verification also occurred for
HOST_ID_ENABLED option.
7.3. CGN Performance Testing
To conclude about the impact of using HOST_ID, a commercial testing
product has been used. This tool supports multiple application
protocols such as HTTP and FTP for both IPv4 and IPv6 (including
encapsulation). The DS-Lite model can be built directly from a port
of this product: IPv4 packets are directly encapsulated in an IPv6
tunnel; the client's port emulates hosts and B4 elements at the same
time. This port is directly connected to the AFTR tunnel endpoint.
The AFTR's IPv4 interface is connected to the testing product server
side where servers are assigned IPv4 addresses.
The testbed setup of this testing is shown in Figure 15:
clients' port +------------------+ servers' side
+------------------+ Testing Tool +------------------+
| +------------------+ |
| |
| |
|IPv4-in-IPv6 tunnel |
| |
| |
| +------------------+ |
+------------------+ AFTR +------------------+
+------------------+
Figure 15: Platform Testbed
7.3.1. Configuration
At the IP level, the testing client port was configured with IPv6
addresses representing the B4. The testing tool also supports the
DS-Lite "level" where the number of clients connected to each B4 and
their addresses are configured. The AFTR address is defined at this
level.
In the current testing, the total number of B4 elements is 5000
behind; One client is connected to each B4 (in total, 5000 clients
are configured). However, the number of active users varies from 10
to 100, 500, 1000 and 10,000 during each testing simulation.
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From the server standpoint, five servers have been assigned IPv4
addresses. These servers support HTTP and FTP traffic. For each
HOST_ID TCP option, the testing was repeated for a different number
of active users (N=10, 100, 500, 1000 and 10,000) and for HTTP and
FTP traffic.
The HOST_ID options are injected by the CGN.
7.3.2. HTTP Testing
The testing duration was about 50 seconds during which the number of
active users varies as a function of time: during the first 10s, the
number of active users reaches the maximum and remains the same for
the next 20 s. Then it decreases to zero during the next 20s.
Hereafter are provided some testing statistics providing some details
about connections' success ratio, latency and other information that
can be useful to evaluate the impact of HOST_ID on the CGN.
+-------+-------+------------+---------+
|No-Opt |O-WING |O-BOUCADAIR3|O-ENABLED|
-----------------------------+-------+-------+------------+---------+
TCP connection established | 1378 | 1267 | 1363 | 1369 |
TCP SYN SENT | 1378 | 1267 | 1363 | 1369 |
Success Ratio | 100 | 100 | 100 | 100 |
TCP Retries | 193 | 193 | 197 | 177 |
TCP timeouts | 140 | 136 | 152 | 111 |
HTTP connect' latencies t=20s| 0,11 | 0,21 | 0,20 | 0,1 |
t=40s| 0,40 | 0,50 | 0,50 | 0,45 |
t=60s| 0,60 | 0,60 | 0,50 | 0,6 |
HTTP throughput received | 46,47 | 45,31 | 45,88 | 46,12 |
TCP Connections Established/s| 20,29 | 19,88 | 20,06 | 20,18 |
-----------------------------+-------+-------+------------+---------+
Figure 16: Results HTTP (N=10)
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+-------+-------+------------+---------+
|No-Opt |O-WING |O-BOUCADAIR3|O-ENABLED|
-----------------------------+-------+-------+------------+---------+
TCP connection established | 1662 | 1739 | 1813 | 1679 |
TCP SYN SENT | 1718 | 1770 | 1819 | 1729 |
Success Ratio | 96 | 98 | 99 | 97 |
TCP Retries | 1577 | 1569 | 1783 | 1576 |
TCP timeouts | 798 | 806 | 934 | 808 |
HTTP connect' latencies t=20s| 1,70 | 2,00 | 1,90 | 1,80 |
t=30s| 3,30 | 2,40 | 2,25 | 3,30 |
t=40s| 4,20 | 3,70 | 3,75 | 4,00 |
t=50s| 5,00 | 4,80 | 4,50 | 5,00 |
HTTP throughput received | 47,56 | 46,65 | 48,59 | 48,06 |
TCP Connections Established/s| 20,94 | 20,53 | 21,35 | 21,19 |
-----------------------------+-------+-------+------------+---------+
Figure 17: Results HTTP (N=100)
+-------+-------+------------+---------+
|No-Opt |O-WING |O-BOUCADAIR3|O-ENABLED|
-----------------------------+-------+-------+------------+---------+
TCP connection established | 1956 | 1923 | 1944 | 1873 |
TCP SYN SENT | 2088 | 2095 | 2137 | 1986 |
Success Ratio | 93 | 91 | 90 | 94 |
TCP Retries | 2734 | 2576 | 2453 | 2773 |
TCP timeouts | 1261 | 1110 | 995 | 1213 |
HTTP connect' latencies t=20s| 2,00 | 1,80 | 1,50 | 2,30 |
t=40s| 4,00 | 3,30 | 2,80 | 4,30 |
t=50s| 6,50 | 6,90 | 6,00 | 8,00 |
HTTP throughput received | 70,19 | 65,00 | 69,81 | 67,13 |
TCP Connections Established/s| 30,69 | 28,41 | 30,50 | 29,38 |
-----------------------------+-------+-------+------------+---------+
Figure 18: Results HTTP (N=1000)
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+-------+-------+------------+---------+
|No-Opt |O-WING |O-BOUCADAIR4|O-ENABLED|
-----------------------------+-------+-------+------------+---------+
TCP connection established | 1576 | 2000 | 1796 | 1998 |
TCP SYN SENT | 2088 | 2304 | 2009 | 2262 |
Success Ratio | 87 | 86 | 89 | 88 |
TCP Retries | 3018 | 3101 | 3013 | 3148 |
TCP timeouts | 1167 | 1298 | 1213 | 1417 |
HTTP connect' latencies t=20s| 2,20 | 3,00 | 2,20 | 2,50 |
t=40s| 3,70 | 3,00 | 3,30 | 3,00 |
t=60s| 7,80 | 5,00 | 7,00 | 5,60 |
t=70s| 9,60 | 6,00 | 8,70 | 7,00 |
HTTP throughput received | 45,00 | 54,52 | 51,45 | 57,20 |
TCP Connections Established/s| 19,98 | 24,05 | 22,45 | 25,04 |
-----------------------------+-------+-------+------------+---------+
Figure 19: Results HTTP (N=10000)
7.3.2.1. Analysis of results
The results clearly show that there is no impact of any HOST_ID
option on session establishment success ratio, which is quite similar
to the success ratio when packets do not hold options or when HOST_ID
options are not used. Also, the number of established connections
does not decrease when any HOST_ID option is injected, so the CGN
performance is not impacted by the fact of adding the HOST_ID
options.
Another important factor to study is the latency that can be caused
by HOST_ID injection. As the results show, the HTTP connection
latency does not increase when HOST_ID is present if we compare the
latency measured at different times for the different options.
As a result, we clearly see that the average throughput measured at
servers is identical, whether HOST_ID options are used or not (given
that the number of session established is quite the same).
Another consequence is that the TCP connection establishment rate at
servers is not decreasing when a HOST_ID option is taken into
account.
7.3.2.2. Conclusion
The results that have been obtained show that the performance of the
CGN is not impacted by HOST_ID option injection even when the number
of active users is high (10,000 is not negligible for a CGN run on an
ordinary Linux machine): neither the session success ratio, nor the
connection latency are impacted by the presence of the HOST_ID in SYN
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packets.
7.3.3. FTP
The same testing was also run for FTP traffic. No particular impact
on the performance of the CGN has been observed.
8. IPTABLES: Modifications to Enforce Policies at the Server Side
8.1. Overview
iptables module has been updated to:
o Log the content of TCP header with HOST_ID
o Drop packets holding a HOST_ID option
o Match any HOST_ID value
o Drop packets holding a specific HOST_ID value
o Strip any existing HOST_ID option
To support the above functionalities, modification should take into
consideration stripping and matching options as described below:
1. To strip the content of any existing HOST_ID option, the shared
library "libxt_TCPOPTSTRIP.so" is modified: the HOST_ID_WING and
HOST_ID_BOUCADAIR Kinds' numbers were defined in the
corresponding source file (libxt_TCPOPTSTRIP.c) with the
corresponding names to enforce the iptables stripping rule.
After enforcing these changes, the shared library must be created
to replace the existing one and to allow applying the rule of
stripping of the HOST_ID options. Once modifications have taken
place, the following command should be used to strip the HOST_ID
options:
iptables -t mangle -A INPUT -j TCPOPTSTRIP -p tcp --strip-options
hostid_wing, hostid_boucadair
2. In order to allow blocking, logging or applying any rule based
upon the HOST_ID_WING or HOST_ID_BOUCADAIR values or range of
values, a HOST_ID shared library must be created to:
* Match HOST_ID options values entered in corresponding iptables
rules,
* Print the HOST_ID rules on screen,
* Save values,
* Check the values (or range values) entered by user if they
respect the limit values of these options.
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In addition to the shared library: a specific Kernel module must
be built to apply HOST_ID matching rules on the packets passing
through the network interfaces. This module compares the HOST_ID
options' values held by packets with the HOST_ID values specified
in the iptables rule table: when a packet matches the HOST_ID's
range, the corresponding rule will be applied for this packet.
The HOST_ID_WING matching value is 2 bytes long corresponding to
HOST_ID_WING data.
The HOST_ID_BOUCADAIR matching value is 8 bytes long corresponding
to Lifetime + Origin field (1 byte) and HOST_ID_WING data (7
bytes).
8.2. Validation
After having updated the iptables package with the suitable HOST_ID
libraries and module, different HOST_ID policies should be applied
and tested on the server side. The testing has been done using a
simple configuration as shown below (Figure 20).
+--------+ +--------+ +--------+ +--------------+
| HOST |-----| B4 |-----| AFTR |-----| local server |
+--------+ +--------+ +--------+ +--------------+
Figure 20: Platform configuration: HOST_ID enforcing policies
In the current testing, the AFTR supports HOST_ID options injection
and iptables is modified at the local server. Logging
recommendations consists of logging the IPv4 address and the HOST_ID
option for each connection. Because HOST_ID is sent only in SYN
packets (in the current implementation), only SYN packets will be
logged to a specific file called iptables.log: the rsyslog.d must be
updated with the corresponding command to log iptables messages into
the specific file. Then rsyslog must be reloaded to apply changes.
8.3. Stripping HOST_ID Options
To strip a certain HOST_ID option, TCPOPTSTRIP rule must be called.
Verification consists in logging and then checking the SYN packets
and more precisely the corresponding TCP options, e.g., the following
rules must be applied to strip HOST_ID_WING:
iptables -t mangle -A INPUT -j TCPOPTSTRIP -p tcp --strip-options
hostid_wing
iptables -A INPUT -j LOG --log-tcp-options -p tcp --syn
The first rule applies for the mangle table. This table allows
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stripping HOST_ID_WING whose role is to remove option Wing's fields
and replaces them by NOP options (NOP=No Operation=0x01). The second
rule enables the logging of SYN packets with the corresponding TCP
options.
After applying these rules (to strip and log HOST_ID_WING) on the
local server, we tried to access the server's HTTP pages from the
host. The test is repeated several times and a different HOST_ID
option is enabled by the AFTR each time.
Then the "iptables.log" file is checked: only one SYN packet is
logged with 4 bytes stripped out in the TCP option part. All IPv4
packets going through the AFTR are also logged to be compared with
the server's logged stripped packets.
The comparison of the SYN packets logged by the server with the SYN
packets sent by the AFTR clearly shows that the stripped option is
HOST_ID_WING (all the header fields have been verified to ensure
packet matching): the 4 bytes corresponding to the HOST_ID_WING
option are replaced with NOP options (each one of the 4 bytes is
equal to '1' = NOP).
The same testing was repeated with HOST_ID_BOUCADAIR. The testing
shows that the 10 bytes corresponding to this option were
successfully stripped.
8.4. Logging a Specific HOST_ID Option Value
The remote server should be able to track connections coming from
different clients; it should log packets headers including the
HOST_ID TCP option information. This can be enforced using the
following command:
iptables -t mangle -A INPUT -j TCPOPTSTRIP -p tcp --strip-options
hostid_wing
Now, to log packets matching a certain HOST_ID value or range of
values, the following rule must be applied:
iptables -A INPUT -p tcp --syn -m hostid --hostid_wing value[:value]
-j LOG -log-tcp-options
This command matches the HOST_ID_WING values held by SYN packets with
the specific value [or the specific range of values] determined by
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the rule.
The testing configuration in Figure 20 was used. The HOST_ID_WING
data are implemented as being the last 16 bits of the IPv4 private
source address. When the HOST_ID_WING option is injected by the CGN,
if the data field value corresponds to the iptables value (or range
of values), the packet header is logged. Otherwise, if the
HOST_ID_WING data is said out of range or the packet does not hold
the HOST_ID_WING option, the packet is not logged.
The same testing was repeated to match HOST_ID_BOUCADAIR data
information:
iptables -A INPUT -p tcp --syn -m hostid --hostid_boucadair value
[:value] -j LOG -log-tcp-options
To verify the logging of a specific Boucadair's value, the
Boucadair's options holding source IP address (Origin=2) or IPv6
prefix (Origin=4) were tested successfully; these data values are
fixed since they depend on the host's address. The two other options
that include source port numbers (variable) cannot be tested by value
because the port number varies for each connection.
The iptables rules to log HOST_ID_BOUCADAIR range values have been
verified successfully for all four HOST_ID_BOUCADAIR options.
8.5. Dropping a specific HOST_ID Option Value
The same testing methodology described in the previous section was
repeated to drop packets matching HOST_ID value (or a range of
values); e.g. to drop SYN packets matching a particular HOST_ID_WING
value:
iptables -A INPUT -p tcp --syn -m hostid --hostid_wing value[:value]
-j DROP
In this testing, the HOST_ID_WING option is enabled at the CGN level.
After applying the previous rule where Wing's specified value
corresponds to the HOST_ID_WING data value (last 16 bits of the
host's IPv4 source address), the hosts tries to access HTTP pages of
the local server. It sends SYN packets but the server does not
respond. Because this packet matches the iptables matching value,
the corresponding rule is applied to the SYN packets: a SYN packet is
dropped so the host does not receive any packet in return.
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When the host is still trying to retrieve pages by sending SYN
packets, the command 'iptables -F' will flush all iptables rules.
Once applied, this command will let the host retrieve the required
pages and the connection is therefore established successfully.
The same testing was repeated for HOST_ID_BOUCADAIR options. SYN
packets matching the corresponding rule value or range of values were
dropped. Once iptables rules are flushed, connection is established
normally.
9. IANA Considerations
This document makes no request of IANA.
10. Security Considerations
Security considerations discussed in [I-D.wing-nat-reveal-option]
should be taken into account.
11. Acknowledgments
Many thanks to M. Meulle, P. Ng Tung and L. Valeyre for their help
and review. Special thanks to C. Jacquenet for his careful review.
12. References
12.1. Normative References
[I-D.wing-nat-reveal-option]
Yourtchenko, A. and D. Wing, "Revealing hosts sharing an
IP address using TCP option",
draft-wing-nat-reveal-option-03 (work in progress),
December 2011.
[RFC6250] Thaler, D., "Evolution of the IP Model", RFC 6250,
May 2011.
12.2. Informative References
[I-D.boucadair-intarea-nat-reveal-analysis]
Boucadair, M., Touch, J., Levis, P., and R. Penno,
"Analysis of Solution Candidates to Reveal a Host
Identifier in Shared Address Deployments",
draft-boucadair-intarea-nat-reveal-analysis-04 (work in
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Internet-Draft Report of NAT Reveal TCP Options July 2012
progress), September 2011.
[RFC6269] Ford, M., Boucadair, M., Durand, A., Levis, P., and P.
Roberts, "Issues with IP Address Sharing", RFC 6269,
June 2011.
Authors' Addresses
Elie Abdo
France Telecom
Issy-les-Moulineaux
Email: elie.abdo@orange.com
Mohamed Boucadair
France Telecom
Email: mohamed.boucadair@orange.com
Jaqueline Queiroz
France Telecom
Issy-les-Moulineaux
Email: jaqueline.queiroz@orange.com
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