wdiff draft-ietf-i2nsf-applicability-02.txt draft-ietf-i2nsf-applicability-03.txt

Network
I2NSF Working Group J. Jeong
Internet-Draft S. Hyun Sungkyunkwan University
Intended status: Informational Sungkyunkwan University S. Hyun
Expires: September 6, 2018 January 3, 2019 Chosun University
T. Ahn
Korea Telecom
S. Hares
Huawei
D. Lopez
Telefonica I+D
March 5,
July 2, 2018

Applicability of Interfaces to Network Security Functions to Network-
Based Security Services
draft-ietf-i2nsf-applicability-02
draft-ietf-i2nsf-applicability-03

Abstract

This document describes the applicability of Interface to Network
Security Functions (I2NSF) to network-based security services in
Network Functions Virtualization (NFV) environments, such as
firewall, deep packet inspection, or attack mitigation engines.

Status of This Memo

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provisions of BCP 78 and BCP 79.

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Task Force (IETF). Note that other groups may also distribute
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and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
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This Internet-Draft will expire on September 6, 2018. January 3, 2019.

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(https://trustee.ietf.org/license-info) in effect on the date of
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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. I2NSF Framework . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Time-dependent Web Access Control Service . . . . . . . . 5
4. I2NSF Framework with SDN SFC . . . . . . . . . . . . . . . . . . 7
4.1.
5. I2NSF Framework with SDN . . . . . . . . . . . . . . . . . . 9
5.1. Firewall: Centralized Firewall System . . . . . . . . . . 10
4.2. 11
5.2. Deep Packet Inspection: Centralized VoIP/VoLTE Security
System . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.3. 12
5.3. Attack Mitigation: Centralized DDoS-attack Mitigation
System . . . . . . . . . . . . . . . . . . . . . . . . . 13
5. 14
6. I2NSF Framework with NFV . . . . . . . . . . . . . . . . . . 16
7. Security Considerations . . . . . . . . . . . . . . . . . . . 15
6. 18
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 15
7. 18
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 15
8. 18
10. Informative References . . . . . . . . . . . . . . . . . . . 15 19
Appendix A. Changes from draft-ietf-i2nsf-applicability-01 draft-ietf-i2nsf-applicability-02 . . . 19 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 22

1. Introduction

Interface to Network Security Functions (I2NSF) defined a framework
and interfaces for interacting with Network Security Functions
(NSFs). The I2NSF framework allows heterogeneous NSFs developed by
different security solution vendors to be used in the NFV environment
by utilizing the capabilities of such products and the virtualization
of security functions in the NFV platform. In the I2NSF framework,
each NSF initially registers the profile of its own capabilities into
the system in order for themselves to be available in the system. In
addition, the Security Controller registers itself to the I2NSF user
so that the user can request security services to the Security
Controller.

This document describes the applicability of I2NSF framework to
network-based security services with a use case of time-dependent web
access control. This document also describes integrating I2NSF
framework with Software-Defined Networking (SDN) technology for
efficient security services and use cases, such as firewall

[opsawg-firewalls], Deep Packet Inspection (DPI), and Distributed
Denial of Service (DDoS) attack mitigation. We implemented the I2NSF
framework based on SDN for these use cases, and the implementation
successfully verified the effectiveness of the I2NSF framework.

2. Terminology

This document uses the terminology described in [RFC7149],
[ITU-T.Y.3300], [ONF-OpenFlow], [ONF-SDN-Architecture],
[ITU-T.X.1252], [ITU-T.X.800], [RFC8329], [i2nsf-terminology],
[consumer-facing-inf-im], [consumer-facing-inf-dm],
[i2nsf-nsf-cap-im], [nsf-facing-inf-dm], [registration-inf-im],
[registration-inf-dm], and [nsf-triggered-steering]. In addition,
the following terms are defined below:

o Software-Defined Networking (SDN): A set of techniques that
enables to directly program, orchestrate, control, and manage
network resources, which facilitates the design, delivery and
operation of network services in a dynamic and scalable manner
[ITU-T.Y.3300].

o Firewall: A service function at the junction of two network
segments that inspects every packet that attempts to cross the
boundary. It also rejects any packet that does not satisfy
certain criteria for, for example, disallowed port numbers or IP
addresses.

o Centralized Firewall System: A centralized firewall that can
establish and distribute policy rules into network resources for
efficient firewall management. These rules can be managed
dynamically by a centralized server for firewall. SDN can work as
a network-based firewall system through a standard interface
between an SDN switch and a firewall function as a vitual network
function (VNF).

o Centralized VoIP Security System: A centralized security system
that handles the security functions required for VoIP and VoLTE
services. SDN can work as a network-based security system through
a standard interface between an SDN switch and a VoIP/VoLTE
security function as a VNF.

o Centralized DDoS-attack Mitigation System: A centralized mitigator
that can establish and distribute access control policy rules into
network resources for efficient DDoS-attack mitigation. These
rules can be managed dynamically by a centralized server for DDoS-
attack mitigation. The SDN controller and switches can
cooperatively work as a network-based firewall system through a
standard interface between an SDN switch and a firewall function
as a VNF running in the SDN controller.

3. I2NSF Framework

This section describes an I2NSF framework and its use case. Figure 1
shows an I2NSF framework [RFC8329] to support network-based security
services. As shown in Figure 1, I2NSF User can use security
functions by delivering high-level security policies, which specify
security requirements the I2NSF user wants to enforce, to the
Security Controller via the Consumer-Facing Interface
[consumer-facing-inf-im][consumer-facing-inf-dm].

The Security Controller receives and analyzes the high-level security
policies from an I2NSF User, and identifies what types of security
capabilities are required to meet these high-level security policies.
The Security Controller then identifies NSFs that have the required
security capabilities, and generates low-level security policies for
each of the NSFs so that the high-level security policies are
eventually enforced by those NSFs. Finally, the Security Controller
sends the generated low-level security policies to the NSFs
[i2nsf-nsf-cap-im][nsf-facing-inf-dm].

The Security Controller requests NSFs to perform low-level security
services via the NSF-Facing Interface. The NSFs are enabled as
Virtual Network Functions (VNFs) on top of virtual machines through
Network Functions Virtualization (NFV) [ETSI-NFV]. In addition, the
Security Controller uses the I2NSF Registration Interface
[registration-inf-im][registration-inf-dm] to communicate with
Developer's Management System (called Developer's Mgmt System) for
registering (or deregistering) the developer's NSFs into (or from)
the NFV system using the I2NSF framework.

The Consumer-Facing Interface between an I2NSF User and the Security
Controller can be implemented using, for example, RESTCONF [RFC8040].
Data models specified by YANG [RFC6020] describe high-level security
policies to be specified by an I2NSF User. The data model defined in
[consumer-facing-inf-dm] can be used for the I2NSF Consumer-Facing
Interface.

Figure 1: I2NSF Framework

The NSF-Facing Interface between Security Controller and NSFs can be
implemented using NETCONF [RFC6241]. YANG data models describe low-
level security policies for the sake of NSFs, which are translated
from the high-level security policies by the Security Controller.
The data model defined in [nsf-facing-inf-dm] can be used for the
I2NSF NSF-Facing Interface.

The Registration Interface between the Security Controller and the
Developer's Mgmt System can be implemented by RESTCONF [RFC8040].
The data model defined in [registration-inf-dm] can be used for the
I2NSF Registration Interface.

Also, the I2NSF framework can enforce multiple chained NSFs for the
low-level security policies by means of service function chaining
(SFC) techniques for the I2NSF architecture described in
[nsf-triggered-steering].

The following describes a security service scenario using the I2NSF
framework.

3.1. Time-dependent Web Access Control Service

This service scenario assumes that an enterprise network
administrator wants to control the staff members' access to Facebook
during business hours. The following is an example high-level
security policy rule that the administrator requests: Block the staff
members' access to Facebook from 9 am to 6 pm. The administrator
sends this high-level security policy to the security controller,
then the security controller identifies required secuity
capabilities, e.g., IP address and port number inspection
capabilities and URL inspection capability. In this scenario, it is
assumed that the IP address and port number inspection capabilities
are required to check whether a received packet is an HTTP packet
from a staff member. The URL inspection capability is required to
check whether the target URL of a received packet is facebook.com or
not.

The Security Controller maintains the security capabilities of each
NSF running in the I2NSF system, which have been reported by the
Developer's Management System via the Registation interface. Based
on this information, the Security Controller identifies NSFs that can
perform the IP address and port number inspection and URL inspection.
In this scenario, it is assumed that an NSF of firewall has the IP
address and port number inspection capabilities and an NSF of web
filter has URL inspection capability.

The Security Controller generates low-level security rules for the
NSFs to perform IP address and port number inspection, URL
inspection, and time checking. Specifically, the Security Controller
may interoperate with an access control server in the enterprise
network in order to retrieve the information (e.g., IP address in
use, company ID, identifier (ID), and role) of each employee that is
currently using the network. Based on the retrieved information, the
Security Controller generates low-level security rules to check
whether the source IP address of a received packet matches any one
being used by a staff member. In addition, the low-level security
rules should be able to determine that a received packet is of HTTP
protocol. The low-level security rules for web filter checks that
the target URL field of a received packet is equal to facebook.com.
Finally, the Security Controller sends the low-level security rules
of the IP address and port number inspection to the NSF of firewall
and the low-level rules for URL inspection to the NSF of web filter.

The following describes how the time-dependent web access control
service is enforced by the NSFs of firewall and web filter.

1. A staff member tries to access Fackbook.com during business
hours, e.g., 10 am.

2. The packet is forwarded from the staff member's device to the
firewall, and the firewall checks the source IP address and port
number. Now the firewall identifies the received packet is an
HTTP packet from the staff member.

3. The firewall triggers the web filter to further inspect the
packet, and the packet is forwarded from the firewall to the web
filter. Service Function Chaining (SFC) technology can be
utilized to support such packet forwarding in the I2NSF framework
[nsf-triggered-steering].

4. The web filter checks the target URL field of the received
packet, and realizes the packet is toward Facebook.com. The web
filter then checks that the current time is in business hours.
If so, the web filter drops the packet, and consequently the
staff member's access to Facebook during business hours is
blocked.

4. I2NSF Framework with SDN

This section describes an I2NSF framework with SDN for SFC

In the I2NSF
applicability architecture, an NSF can trigger an advanced security
action (e.g., DPI and use cases, such as firewall, deep DDoS attack mitigation) on a packet
inspection, and DDoS-attack mitigation functions. SDN enables some based on
the result of its own security inspection of the packet. For
example, a firewall triggers further inspection of a suspicious
packet filtering rules with DPI. For this advanced security action to be enforced in fulfilled,
the network switches by
controlling their suspicious packet forwarding rules. By taking advantage of
this capability of SDN, it is possible should be forwarded from the current NSF to optimize the process of
successor NSF. Service Function Chaining (SFC) [RFC7665] is a
technology that enables this advanced security action by steering a
packet with multiple service enforcement in functions (e.g., NSFs), and this
technology can be utilized by the I2NSF system.

Figure 2 shows an I2NSF framework [RFC8329] with SDN networks architecture to support network-based security services. In this system, the
enforcement of
advanced security policy rules is divided into the SDN switches action.

SFC generally requires classifiers and NSFs. Especially, SDN switches enforce simple service function forwarders
(SFFs); classifiers are responsible for determining which service
function path (SFP) (i.e., an ordered sequence of service functions)
a given packet filtering
rules that can be translated into their packet forwarding should pass through, according to pre-configured
classification rules,
whereas NSFs enforce NSF-related security rules requiring and SFFs perform forwarding the
security capabilities of given packet to
the NSFs. For this purpose, next service function (e.g., NSF) on the Security
Controller instructs SFP of the Switch Controller via NSF-Facing Interface
so that SDN switches can perform packet by
referring to their forwarding tables. In the required security services I2NSF architecture with
flow tables under the supervision of
SFC, the Switch Controller (i.e., SDN
Controller).

As an example, let us consider two different types of security rules:
Rule A is a simple packet fltering rule that checks only the IP
address and port number controller can take responsibilities of a given packet, whereas rule B is a time-
consuming packet inspection rule generating
classification rules for classifiers and forwarding tables for SFFs.
In particular, by analyzing whether an attached
file being transmitted over a flow of packets contains malware. Rule
A high-level security policies from I2NSF
users, the security controller can be translated into packet forwarding construct SFPs that are required
to meet the high-level security policies, generates classification
rules of SDN switches and
thus be enforced by the switches. In contrast, rule B cannot be
enforced by switches, but it can be enforced by NSFs SFPs, and then configures classifiers with anti-
malware capability. Specifically, a flow of the
classification rules so that relevant traffic packets is forwarded to
and reassembled by an NSF to reconstruct can follow the attached file stored in
SFPs. Also, based on the flow global view of packets. The NSF then analyzes the file to check instances available in
the
existence of malware. If system, the file contains malware, security controller can construct forwarding tables
required for SFFs to forward a given packet to the next NSF drops over the packets.

In an I2NSF framework with SDN, the Security Controller can analyze
given security policy rules and automatically determine which of the
given security policy rules should be enforced by SDN switches and
which should be enforced by NSFs. If some of the given rules
requires security capabilities that can be provided by SDN switches,
then the Security Controller instructs the Switch Controller via NSF-
Facing Interface so that SDN switches can enforce those security
policy rules with flow tables under the supervision of the Switch
Controller (i.e., SDN Controller). Or if some rules require security
capabilities that can be provided by not SDN switches but NSFs, then
the Security Controller instructs relevant NSFs to enforce those
rules.

+------------+
|
SFP.

+------------+
| I2NSF User |
+------------+
^
| Consumer-Facing Interface
v
+-------------------+ Registration +-----------------------+
|Security Controller|<-------------------->|Developer's Mgmt System|
+-------------------+ Interface +-----------------------+
^ ^
| | NSF-Facing Interface
| v |-------------------------
| +----------------+ +---------------+ +-----------------------+ |
+-+-+-v-+-+-+-+-+-+ +------v-------+
| NSF-1 |-| NSF-2 |...| NSF-n +-----------+ | ------>| NSF-1 |
| (Firewall) |Classifier | | (DPI) | |(DDoS-Attack Mitigator)| | +----------------+ +---------------+ +-----------------------+ (Firewall) | ^
| +-----------+ | | v +--------------+
| +--------+ +-----+ |<-----| +--------------+
| | SFF | | +--------+
| ^
| |
| V SDN Network
+--|----------------------------------------------------------------+
| V NSF-Facing Interface |
| +-----------------+ |
| |Switch Controller| |
| +-----------------+ |
| ^ |----->| NSF-2 |
| +-----+ | SDN Southbound Interface | | v (DPI) |
+-+-+-+-+-+-+-+-+-+ | +--------+ +--------+ +--------+ +--------+ +--------------+
| .
| |Switch 1|-|Switch 2|-|Switch 3|......|Switch m| .
| .
| +--------+ +--------+ +--------+ +--------+ +-----------------------+
------>| NSF-n |
+-------------------------------------------------------------------+
|(DDoS-Attack Mitigator)|
+-----------------------+

Figure 2: An I2NSF Framework with SDN Network

The following subsections introduce three use cases for cloud-based SFC

To trigger an advanced security services: (i) firewall system, (ii) deep packet inspection
system, and (iii) attack mitigation system. [RFC8192]

4.1. Firewall: Centralized Firewall System

A centralized network firewall can manage each network resource and
firewall rules can be managed flexibly by action in the I2NSF architecture, the
current NSF appends a centralized server for
firewall (called Firewall). The centralized network firewall
controls each switch metadata describing the security capability
required for the network resource management advanced action to the suspicious packet and sends
the
firewall rules can be added or deleted dynamically.

The procedure of firewall operations in this system is as follows:

1. A switch forwards an unknown flow's packet to one of the Switch
Controllers.

2. The Switch Controller forwards classifier. Based on the unknown flow's packet to metadata information, the
classifier searches an
appropriate security service application, such as SFP which includes an NSF with the Firewall.

3. The Firewall analyzes, typically, required
security capability, changes the headers SFP-related information (e.g.,
service path identifier and contents service index [RFC8300]) of the
packet.

4. If the Firewall regards the packet as a malicious one
with a
suspicious pattern, it reports the malicious new SFP that has been found, and then forwards the packet to
the Switch
Controller.

5. The Switch Controller installs new rules (e.g., drop packets with SFF. When receiving the suspicious pattern) into underlying switches.

6. The suspected packets are dropped by these switches.

Existing SDN protocols can be used through standard interfaces
between packet, the firewall application and switches
[RFC7149][ITU-T.Y.3300][ONF-OpenFlow] [ONF-SDN-Architecture].

Legacy firewalls have some challenges SFF checks the SFP-related
information such as the expensive cost,
performance, management of access control, establishment of policy, service path identifier and packet-based access mechanism. The proposed framework can
resolve service index
contained in the challenges through packet and forwards the above centralized firewall system
based packet to the next NSF on SDN as follows:

o Cost: The cost
the SFP of adding firewalls the packet, according to network resources its forwarding table.

5. I2NSF Framework with SDN

This section describes an I2NSF framework with SDN for I2NSF
applicability and use cases, such as
routers, gateways, firewall, deep packet
inspection, and switches is substantial due DDoS-attack mitigation functions. SDN enables some
packet filtering rules to be enforced in the reason
that we need to add firewall on each network resource. To solve
this, each network resource can be managed centrally such that a
single firewall is manipulated switches by a centralized server.

o Performance: The performance
controlling their packet forwarding rules. By taking advantage of firewalls is often slower than the
link speed
this capability of network interfaces. Every network resource for
firewall needs to check firewall rules according SDN, it is possible to network
conditions. Firewalls can be adaptively deployed among network
switches, depending on network conditions in optimize the framework.

o The management of access control: Since there may be hundreds process of
network resources
security service enforcement in a network, the dynamic management of access
control for I2NSF system.

Figure 3 shows an I2NSF framework [RFC8329] with SDN networks to
support network-based security services like firewall is a challenge. services. In this system, the framework, firewall rules can be dynamically added for new
malware.

o The establishment
enforcement of policy: Policy should be established for each
network resource. However, it is difficult to describe what flows
are permitted or denied for firewall within a specific
organization network under management. Thus, a centralized view
is helpful to determine security policies for such a network.

o Packet-based access mechanism: Packet-based access mechanism policy rules is
not enough for firewall in practice since divided into the basic unit of access
control is usually users or applications. Therefore, application
level SDN switches
and NSFs. Especially, SDN switches enforce simple packet filtering
rules that can be defined and added to translated into their packet forwarding rules,
whereas NSFs enforce NSF-related security rules requiring the firewall system
through
security capabilities of the NSFs. For this purpose, the centralized server.

4.2. Deep Packet Inspection: Centralized VoIP/VoLTE Security System

A centralized VoIP/VoLTE security system
Controller instructs the Switch Controller via NSF-Facing Interface
so that SDN switches can monitor each VoIP/VoLTE perform the required security services with
flow and manage VoIP/VoLTE tables under the supervision of the Switch Controller (i.e., SDN
Controller).

As an example, let us consider two different types of security rules controlled by rules:
Rule A is a centralized
server for VoIP/VoLTE security service called VoIP Intrusion
Prevention System (IPS). The VoIP/VoLTE security system controls
each switch for simple packet fltering rule that checks only the VoIP/VoLTE call IP
address and port number of a given packet, whereas rule B is a time-
consuming packet inspection rule for analyzing whether an attached
file being transmitted over a flow management of packets contains malware. Rule
A can be translated into packet forwarding rules of SDN switches and
thus be enforced by manipulating the rules that can switches. In contrast, rule B cannot be added, deleted or modified dynamically.

A centralized VoIP/VoLTE security system
enforced by switches, but it can cooperate be enforced by NSFs with a network
firewall to realize VoIP/VoLTE security service. anti-
malware capability. Specifically, a
network firewall performs basic security checks flow of an unknown flow's
packet observed packets is forwarded to
and reassembled by a switch. If an NSF to reconstruct the network firewall detects that attached file stored in
the packet is an unknown VoIP call flow's packet that exhibits some
suspicious patterns, flow of packets. The NSF then it triggers analyzes the VoIP/VoLTE security system
for more specialized security analysis of the suspicious VoIP call
packet.

The procedure of VoIP/VoLTE security operations in this system is as
follows:

1. A switch forwards an unknown flow's packet to the Switch
Controller, and the Switch Controller further forwards the
unknown flow's packet file to check the Firewall for basic security
inspection.

2. The Firewall analyzes the header fields of the packet, and
figures out that this is an unknown VoIP call flow's signal
packet (e.g., SIP packet) of a suspicious pattern.

3. The Firewall triggers an appropriate security service function,
such as VoIP IPS, for detailed security analysis
existence of malware. If the
suspicious signal packet. That is, the firewall sends the packet
to file contains malware, the Service Function Forwarder (SFF) in NSF drops
the packets.

In an I2NSF framework
[nsf-triggered-steering], as shown in Figure 2. The SFF forwards
the suspicious signal packet to the VoIP IPS.

4. The VoIP IPS analyzes with SDN, the headers Security Controller can analyze
given security policy rules and contents automatically determine which of the signal
packet, such as calling number
given security policy rules should be enforced by SDN switches and session description headers
[RFC4566].

5. If, for example, the VoIP IPS regards the packet as a spoofed
packet
which should be enforced by hackers or a scanning packet searching for VoIP/VoLTE
devices, it drops NSFs. If some of the packet. In addition, given rules
requires security capabilities that can be provided by SDN switches,
then the VoIP IPS requests Security Controller instructs the Switch Controller to block via NSF-
Facing Interface so that packet and SDN switches can enforce those security
policy rules with flow tables under the subsequent
packets that have supervision of the same call-id.

6. The Switch
Controller installs new rules (e.g., drop packets)
into underlying switches.

7. The illegal packets are dropped by these switches.

Existing SDN protocols can be used through standard interfaces
between the VoIP IPS application and switches [RFC7149][ITU-T.Y.3300]
[ONF-OpenFlow][ONF-SDN-Architecture].

Legacy hardware based VoIP IPS has some challenges, such as
provisioning time, the granularity of security, expensive cost, and
the establishment of policy. The I2NSF framework can resolve the
challenges through the above centralized VoIP/VoLTE security system
based on (i.e., SDN as follows:

o Provisioning: The provisioning time of setting up a legacy VoIP
IPS to network is substantial because it takes from some hours to Controller). Or if some days. By managing the network resources centrally, VoIP IPS
can provide more agility in provisioning both virtual and physical
network resources from a central location.

o The granularity of security: The security rules of a legacy VoIP
IPS are compounded considering the granularity of security. The
proposed framework can provide more granular security by
centralizing security control into a switch controller. The VoIP
IPS can effectively manage require security rules throughout the network.

o Cost: The cost of adding VoIP IPS to network resources, such as
routers, gateways, and switches is substantial due to the reason
capabilities that we need to add VoIP IPS on each network resource. To solve
this, each network resource can be managed centrally such that a
single VoIP IPS is manipulated provided by a centralized server.

o The establishment of policy: Policy should be established for each
network resource. However, it not SDN switches but NSFs, then
the Security Controller instructs relevant NSFs to enforce those
rules.

+------------+
| I2NSF User |
+------------+
^
| Consumer-Facing Interface
v
+-------------------+ Registration +-----------------------+
|Security Controller|<-------------------->|Developer's Mgmt System|
+-------------------+ Interface +-----------------------+
^ ^
| | NSF-Facing Interface
| v
| +----------------+ +---------------+ +-----------------------+
| | NSF-1 |-| NSF-2 |...| NSF-n |
| | (Firewall) | | (DPI) | |(DDoS-Attack Mitigator)|
| +----------------+ +---------------+ +-----------------------+
| ^
| |
| v
| +--------+
| | SFF |
| +--------+
| ^
| |
| V SDN Network
+--|----------------------------------------------------------------+
| V NSF-Facing Interface |
| +-----------------+ |
| |Switch Controller| |
| +-----------------+ |
| ^ |
| | SDN Southbound Interface |
| v |
| +--------+ +--------+ +--------+ +--------+ |
| |Switch 1|-|Switch 2|-|Switch 3|......|Switch m| |
| +--------+ +--------+ +--------+ +--------+ |
+-------------------------------------------------------------------+

Figure 3: An I2NSF Framework with SDN Network

The following subsections introduce three use cases for cloud-based
security services: (i) firewall system, (ii) deep packet inspection
system, and (iii) attack mitigation system. [RFC8192]

5.1. Firewall: Centralized Firewall System

A centralized network firewall can manage each network resource and
firewall rules can be managed flexibly by a centralized server for
firewall (called Firewall). The centralized network firewall
controls each switch for the network resource management and the
firewall rules can be added or deleted dynamically.

The procedure of firewall operations in this system is as follows:

1. A switch forwards an unknown flow's packet to one of the Switch
Controllers.

2. The Switch Controller forwards the unknown flow's packet to an
appropriate security service application, such as the Firewall.

3. The Firewall analyzes, typically, the headers and contents of the
packet.

4. If the Firewall regards the packet as a malicious one with a
suspicious pattern, it reports the malicious packet to the Switch
Controller.

5. The Switch Controller installs new rules (e.g., drop packets with
the suspicious pattern) into underlying switches.

6. The suspected packets are dropped by these switches.

Existing SDN protocols can be used through standard interfaces
between the firewall application and switches
[RFC7149][ITU-T.Y.3300][ONF-OpenFlow] [ONF-SDN-Architecture].

Legacy firewalls have some challenges such as the expensive cost,
performance, management of access control, establishment of policy,
and packet-based access mechanism. The proposed framework can
resolve the challenges through the above centralized firewall system
based on SDN as follows:

o Cost: The cost of adding firewalls to network resources such as
routers, gateways, and switches is substantial due to the reason
that we need to add firewall on each network resource. To solve
this, each network resource can be managed centrally such that a
single firewall is manipulated by a centralized server.

o Performance: The performance of firewalls is often slower than the
link speed of network interfaces. Every network resource for
firewall needs to check firewall rules according to network
conditions. Firewalls can be adaptively deployed among network
switches, depending on network conditions in the framework.

o The management of access control: Since there may be hundreds of
network resources in a network, the dynamic management of access
control for security services like firewall is a challenge. In
the framework, firewall rules can be dynamically added for new
malware.

o The establishment of policy: Policy should be established for each
network resource. However, it is difficult to describe what flows
are permitted or denied for firewall within a specific
organization network under management. Thus, a centralized view
is helpful to determine security policies for such a network.

o Packet-based access mechanism: Packet-based access mechanism is
not enough for firewall in practice since the basic unit of access
control is usually users or applications. Therefore, application
level rules can be defined and added to the firewall system
through the centralized server.

5.2. Deep Packet Inspection: Centralized VoIP/VoLTE Security System

A centralized VoIP/VoLTE security system can monitor each VoIP/VoLTE
flow and manage VoIP/VoLTE security rules controlled by a centralized
server for VoIP/VoLTE security service called VoIP Intrusion
Prevention System (IPS). The VoIP/VoLTE security system controls
each switch for the VoIP/VoLTE call flow management by manipulating
the rules that can be added, deleted or modified dynamically.

A centralized VoIP/VoLTE security system can cooperate with a network
firewall to realize VoIP/VoLTE security service. Specifically, a
network firewall performs basic security checks of an unknown flow's
packet observed by a switch. If the network firewall detects that
the packet is an unknown VoIP call flow's packet that exhibits some
suspicious patterns, then it triggers the VoIP/VoLTE security system
for more specialized security analysis of the suspicious VoIP call
packet.

The procedure of VoIP/VoLTE security operations in this system is as
follows:

1. A switch forwards an unknown flow's packet to the Switch
Controller, and the Switch Controller further forwards the
unknown flow's packet to the Firewall for basic security
inspection.

2. The Firewall analyzes the header fields of the packet, and
figures out that this is an unknown VoIP call flow's signal
packet (e.g., SIP packet) of a suspicious pattern.

3. The Firewall triggers an appropriate security service function,
such as VoIP IPS, for detailed security analysis of the
suspicious signal packet. That is, the firewall sends the packet
to the Service Function Forwarder (SFF) in the I2NSF framework
[nsf-triggered-steering], as shown in Figure 3. The SFF forwards
the suspicious signal packet to the VoIP IPS.

4. The VoIP IPS analyzes the headers and contents of the signal
packet, such as calling number and session description headers
[RFC4566].

5. If, for example, the VoIP IPS regards the packet as a spoofed
packet by hackers or a scanning packet searching for VoIP/VoLTE
devices, it drops the packet. In addition, the VoIP IPS requests
the Switch Controller to block that packet and the subsequent
packets that have the same call-id.

6. The Switch Controller installs new rules (e.g., drop packets)
into underlying switches.

7. The illegal packets are dropped by these switches.

Existing SDN protocols can be used through standard interfaces
between the VoIP IPS application and switches [RFC7149][ITU-T.Y.3300]
[ONF-OpenFlow][ONF-SDN-Architecture].

o Provisioning: The provisioning time of setting up a legacy VoIP
IPS to network is substantial because it takes from some hours to
some days. By managing the network resources centrally, VoIP IPS
can provide more agility in provisioning both virtual and physical
network resources from a central location.

o Cost: The cost of adding VoIP IPS to network resources, such as
routers, gateways, and switches is substantial due to the reason
that we need to add VoIP IPS on each network resource. To solve
this, each network resource can be managed centrally such that a
single VoIP IPS is manipulated by a centralized server.

o The establishment of policy: Policy should be established for each
network resource. However, it is difficult to describe what flows
are permitted or denied for VoIP IPS within a specific
organization network under management. Thus, a centralized view
is helpful to determine security policies for such a network.

5.3. Attack Mitigation: Centralized DDoS-attack Mitigation System

A centralized DDoS-attack mitigation can manage each network resource
and manipulate rules to each switch through a centralized server for
DDoS-attack mitigation (called DDoS-attack Mitigator). The
centralized DDoS-attack mitigation system defends servers against
DDoS attacks outside private network, that is, from public network.

Servers are categorized into stateless servers (e.g., DNS servers)
and stateful servers (e.g., web servers). For DDoS-attack
mitigation, traffic flows in switches are dynamically configured by
traffic flow forwarding path management according to the category of
servers [AVANT-GUARD]. Such a managenent should consider the load
balance among the switches for the defense against DDoS attacks.

The procedure of DDoS-attack mitigation operations in this system is
as follows:

1. A Switch periodically reports an inter-arrival pattern of a
flow's packets to one of the Switch Controllers.

2. The Switch Controller forwards the flow's inter-arrival pattern
to an appropriate security service application, such as DDoS-
attack Mitigator.

3. The DDoS-attack Mitigator analyzes the reported pattern for the
flow.

4. If the DDoS-attack Mitigator regards the pattern as a DDoS
attack, it computes a packet dropping probability corresponding
to suspiciousness level and reports this DDoS-attack flow to
Switch Controller.

5. The Switch Controller installs new rules into switches (e.g.,
forward packets with the suspicious inter-arrival pattern with a
dropping probability).

6. The suspicious flow's packets are randomly dropped by switches
with the dropping probability.

For the above centralized DDoS-attack mitigation system, the existing
SDN protocols can be used through standard interfaces between the
DDoS-attack mitigator application and switches [RFC7149]
[ITU-T.Y.3300][ONF-OpenFlow][ONF-SDN-Architecture].

The centralized DDoS-attack mitigation system has challenges similar
to the centralized firewall system. The proposed framework can
resolve the challenges through the above centralized DDoS-attack
mitigation system based on SDN as follows:

o Cost: The cost of adding DDoS-attack mitigators to network
resources such as routers, gateways, and switches is substantial
due to the reason that we need to add DDoS-attack mitigator on
each network resource. To solve this, each network resource can
be managed centrally such that a single DDoS-attack mitigator is
manipulated by a centralized server.

o Performance: The performance of DDoS-attack mitigators is often
slower than the link speed of network interfaces. The checking of
DDoS attacks may reduce the performance of the network interfaces.
DDoS-attack mitigators can be adaptively deployed among network
switches, depending on network conditions in the framework.

o The management of network resources: Since there may be hundreds
of network resources in an administered network, the dynamic
management of network resources for performance (e.g., load
balancing) is a challenge for DDoS-attack mitigation. In the
framework, as dynamic network resource management, traffic flow
forwarding path management can handle the load balancing of
network switches [AVANT-GUARD]. With this management, the current
and near-future workload can be spread among the network switches
for DDoS-attack mitigation. In addition, DDoS-attack mitigation
rules can be dynamically added for new DDoS attacks.

o The establishment of policy: Policy should be established for each
network resource. However, it is difficult to describe what flows
are permitted or denied for new DDoS-attacks (e.g., DNS reflection
attack) within a specific organization network under management.
Thus, a centralized view is helpful to determine security policies
for such a network.

So far this document has described the procedure and impact of the
three use cases for network-based security services using the I2NSF
framework with SDN networks. To support these use cases in the
proposed data-driven security service framework, YANG data models
described in [consumer-facing-inf-dm], [nsf-facing-inf-dm], and
[registration-inf-dm] can be used as Consumer-Facing Interface, NSF-
Facing Interface, and Registration Interface, respectively, along
with RESTCONF [RFC8040] and NETCONF [RFC6241].

6. I2NSF Framework with NFV

This section discusses the implementation of the I2NSF framework with
Network Functions Virtualization (called NFV).

+--------------------+
+-------------------------------------------+ | ---------------- |
| I2NSF User (OSS/BSS) | | | NFV | |
+------+------------------------------------+ | | Orchestrator +-+ |
| Consumer-Facing Interface | ---+------------ | |
+------|------------------------------------+ | | | |
| ----+-------------------------------- | | | | |
| | Security Controller(EM) | | | | | |
| ----+-------------+-------------+---- | | ---+---------- | |
| | NSF-Facing Interface | |(a)-| Developer's| | |
| ----+---- ----+---- ----+---- | | Mgmt System| | |
| |NSF(VNF)| |NSF(VNF)| |NSF(VNF)| |(b)-| (VNFM) | | |
| ----+---- ----+---- ----+---- | | ---+---------- | |
| | | | | | | | |
+------|-------------|-------------|--------+ | | | |
| | | | | | |
+------+-------------+-------------+--------+ | | | |
| NFV Infrastructure (NFVI) | | | | |
| ----------- ----------- ----------- | | | | |
| | Virtual | | Virtual | | Virtual | | | | | |
| | Compute | | Storage | | Network | | | | | |
| ----------- ----------- ----------- | | ---+------ | |
| +---------------------------------------+ | | | | | |
| | Virtualization Layer | |--|-| VIM(s) +-------- |
| +---------------------------------------+ | | | | |
| +---------------------------------------+ | | ---------- |
| | ----------- ----------- ----------- | | | |
| | | Compute | | Storage | | Network | | | | |
| | | hardware| | hardware| | hardware| | | | |
| | ----------- ----------- ----------- | | | |
| | Hardware resources | | | NFV Management |
| +---------------------------------------+ | | and Orchestration |
+-------------------------------------------+ +--------------------+
(a) = Registration Interface
(b) = Ve-Vnfm Interface

Figure 4: I2NSF Framework Implementation in NFV Reference
Architectural Framework

NFV is difficult to describe what flows
are permitted or denied for VoIP IPS within a specific
organization network under management. Thus, a centralized view
is helpful to determine security policies promising technology for such a network.

4.3. Attack Mitigation: Centralized DDoS-attack Mitigation System

A centralized DDoS-attack mitigation can manage each improving the elasticity and
efficiency of network resource
and manipulate rules utilization. In NFV environments,
NSFs can be deployed in the forms of software-based virtual instances
rather than physical appliances. Virtualizing NSFs makes it possible
to each switch through a centralized server for
DDoS-attack mitigation (called DDoS-attack Mitigator). The
centralized DDoS-attack mitigation system defends servers against
DDoS attacks outside private network, that is, from public network.

Servers are categorized into stateless servers (e.g., DNS servers) rapidly and stateful servers (e.g., web servers). For DDoS-attack
mitigation, traffic flows in switches are dynamically configured flexibly respond to the amount of service requests by
traffic flow forwarding path management
dynamically increasing or decreasing the number of NSF instances.
Moreover, NFV technology facilitates flexibly including or excluding
NSFs from multiple security solution vendors according to the category changes
on security requirements. In order to take advantages of
servers [AVANT-GUARD]. Such a managenent should consider the load
balance among the switches for NFV
technology, the defense against DDoS attacks.

The procedure I2NSF framework can be implemented on top of DDoS-attack mitigation operations in this system is an NFV
infrastructure as follows:

1. A Switch periodically reports show in Figure 4.

Figure 4 shows an inter-arrival pattern of a
flow's packets to one of I2NSF framework implementation based on the Switch Controllers.

2. The Switch Controller forwards NFV
reference architecture that the flow's inter-arrival pattern
to an appropriate security service application, such as DDoS-
attack Mitigator.

3. European Telecommunications Standards
Institute (ETSI) defines [ETSI-NFV]. The NSFs are deployed as
virtual network functions (VNFs) in Figure 4. The DDoS-attack Mitigator analyzes Developer's
Management System in the reported pattern I2NSF framework is responsible for creating
or removing NSF instances, and can be implemented as the
flow.

4. If virtual
network functions manager (VNFM) in the DDoS-attack Mitigator regards NFV architecture that
performs the pattern as a DDoS
attack, it computes a packet dropping probability corresponding
to suspiciousness level and reports this DDoS-attack flow to
Switch Controller.

5. life-cycle management of VNFs. The Switch Security Controller installs new rules into switches (e.g.,
forward packets with
can be implemented as the suspicious inter-arrival pattern with a
dropping probability).

6. The suspicious flow's packets are randomly dropped by switches
with Element Management (EM) in the dropping probability.

For NFV
architecture that controls and monitors the above centralized DDoS-attack mitigation system, configurations (e.g.,
function parameters and security policy rules) of VNFs. Finally, the existing
SDN protocols
I2NSF User can be used through standard interfaces between implemented as OSS/BSS (Operational Support
Systems/Business Support Systems) in the
DDoS-attack mitigator application and switches [RFC7149]
[ITU-T.Y.3300][ONF-OpenFlow][ONF-SDN-Architecture].

The centralized DDoS-attack mitigation system has challenges similar
to NFV architecture that
provides interfaces for users in the centralized firewall NFV system.

The proposed framework can
resolve the challenges through operation procedure in the above centralized DDoS-attack
mitigation system I2NSF framework based on SDN the NFV
architecture is as follows:

o Cost:

1. The cost of adding DDoS-attack mitigators to network
resources such as routers, gateways, and switches is substantial
due to the reason that we need to add DDoS-attack mitigator on
each network resource. To solve this, each network resource can
be managed centrally such that a single DDoS-attack mitigator is
manipulated by Developer's Mgmt System (DMS) has a centralized server.

o Performance: The performance set of DDoS-attack mitigators is often
slower than the link speed virtual machine
(VM) images of network interfaces. NSFs, and each VM image can be used to create an
NSF instance that provides a set of security capabilities. The checking
DMS initially registers a mapping table of
DDoS attacks may reduce the performance ID of each VM
image and the network interfaces.
DDoS-attack mitigators can be adaptively deployed among network
switches, depending on network conditions in the framework.

o The management set of network resources: Since there may capabilities that can be hundreds
of network resources in provided by an administered network, NSF
instance created from the dynamic
management of network resources for performance (e.g., load
balancing) is a challenge for DDoS-attack mitigation. In VM image into the
framework, as dynamic network resource management, traffic flow
forwarding path management can handle Security Controller.

2. If the load balancing Security Controller does not have any instantiated NSF
that has the set of
network switches [AVANT-GUARD]. With this management, capabilities required to meet the current
and near-future workload can be spread among security
requirements from users, it searches the network switches
for DDoS-attack mitigation. In addition, DDoS-attack mitigation
rules can be dynamically added mapping table
(registered by the DMS) for new DDoS attacks.

o The establishment the VM image ID corresponding to the
required set of policy: Policy should be established for each
network resource. However, it is difficult capabilities.

3. The Security Controller requests the DMS to describe what flows
are permitted or denied instantiate an NSF
with the VM image ID.

4. When receiving the instantiation request, the DMS first asks the
NFV orchestrator for new DDoS-attacks (e.g., DNS reflection
attack) within a specific organization network under management.
Thus, a centralized view is helpful the permission required to determine security policies create the NSF
instance, requests the VIM to allocate resources for such a network.

So far this document the NSF
instance, and finally creates the NSF instance based on the
allocated resources.

5. Once the NSF instance has described been created, the DMS performs the
initial configurations of the procedure NSF instance and impact then notifies the
Security Controller of the
three use cases for network-based NSF instance.

6. After being notified of the created NSF instance, the Security
Controller delivers low-level security services using policy rules to the NSF
instance for policy enforcement.

The I2NSF framework with SDN networks. To support these use cases in the
proposed data-driven security service framework, YANG data models
described in [consumer-facing-inf-dm], [nsf-facing-inf-dm], and
[registration-inf-dm] can be used as Consumer-Facing Interface, NSF-
Facing Interface, and implemented based on the NFV architecture.
Note that the registration of the capabilities of NSFs is performed
through the Registration Interface, respectively, along
with RESTCONF [RFC8040] Interface and NETCONF [RFC6241].

5. the life-cycle management for
NSFs (VNFs) is performed through the Ve-Vnfm interface, as shown in
Figure 4. More details about the I2NSF framework based on the NFV
reference architecture are described in [i2nsf-nfv-architecture].

7. Security Considerations

The I2NSF framework with SDN networks in this document is derived
from the I2NSF framework [RFC8329], so the security considerations of
the I2NSF framework should be included in this document. Therefore,
proper secure communication channels should be used the delivery of
control or management messages among the components in the proposed
framework.

This document shares all the security issues of SDN that are
specified in the "Security Considerations" section of [ITU-T.Y.3300].

8. Acknowledgments

This work was supported by Institute for Information & communications
Technology Promotion (IITP) grant funded by the Korea government
(MSIP) (No.R-20160222-002755, Cloud based Security Intelligence
Technology Development for the Customized Security Service
Provisioning).

9. Contributors

I2NSF is a group effort. I2NSF has had a number of contributing
authors. The following are considered co-authors:

o Hyoungshick Kim (Sungkyunkwan University)

o Jinyong Tim Kim (Sungkyunkwan University)
o Hyunsik Yang (Soongsil University)

o Younghan Kim (Soongsil University)

o Jung-Soo Park (ETRI)

o Se-Hui Lee (Korea Telecom)

o Mohamed Boucadair (Orange)

10. Informative References

[AVANT-GUARD]
Shin, S., Yegneswaran, V., Porras, P., and G. Gu, "AVANT-
GUARD: Scalable and Vigilant Switch Flow Management in
Software-Defined Networks", ACM CCS, November 2013.

[consumer-facing-inf-dm]
Jeong, J., Kim, E., Ahn, T., Kumar, R., and S. Hares,
"I2NSF Consumer-Facing Interface YANG Data Model", draft-
ietf-i2nsf-consumer-facing-interface-dm-00
ietf-i2nsf-consumer-facing-interface-dm-01 (work in
progress), March July 2018.

[consumer-facing-inf-im]
Kumar, R., Lohiya, A., Qi, D., Bitar, N., Palislamovic,
S., Xia, L., and J. Jeong, "Information Model for
Consumer-Facing Interface to Security Controller", draft-
kumar-i2nsf-client-facing-interface-im-04
kumar-i2nsf-client-facing-interface-im-06 (work in
progress), October 2017. July 2018.

[ETSI-NFV]
ETSI GS NFV 002 V1.1.1, "Network Functions Virtualisation Virtualization
(NFV); Architectural Framework", October 2013.

[i2nsf-nfv-architecture]
Yang, H. and Y. Kim, "I2NSF on the NFV Reference
Architecture", draft-yang-i2nsf-nfv-architecture-02 (work
in progress), June 2018.

[i2nsf-nsf-cap-im]
Xia, L., Strassner, J., Basile, C., and D. Lopez,
"Information Model of NSFs Capabilities", draft-ietf-
i2nsf-capability-00
i2nsf-capability-02 (work in progress), September 2017. July 2018.

[i2nsf-terminology]
Hares, S., Strassner, J., Lopez, D., Xia, L., and H.
Birkholz, "Interface to Network Security Functions (I2NSF)
Terminology", draft-ietf-i2nsf-terminology-05 (work in
progress), January 2018.

[ITU-T.X.1252]
Recommendation ITU-T X.1252, "Baseline Identity Management
Terms and Definitions", April 2010.

[ITU-T.X.800]
Recommendation ITU-T X.800, "Security Architecture for
Open Systems Interconnection for CCITT Applications",
March 1991.

[ITU-T.Y.3300]
Recommendation ITU-T Y.3300, "Framework of Software-
Defined Networking", June 2014.

[nsf-facing-inf-dm]
Kim, J., Jeong, J., Park, J., Hares, S., and Q. Lin,
"I2NSF Network Security Function-Facing Interface YANG
Data Model", draft-ietf-i2nsf-nsf-facing-interface-data-
model-00
model-01 (work in progress), March July 2018.

[nsf-triggered-steering]
Hyun, S., Jeong, J., Park, J., and S. Hares, "Service
Function Chaining-Enabled I2NSF Architecture", draft-hyun-
i2nsf-nsf-triggered-steering-05
i2nsf-nsf-triggered-steering-06 (work in progress), March July
2018.

[ONF-OpenFlow]
ONF, "OpenFlow Switch Specification (Version 1.4.0)",
October 2013.

[ONF-SDN-Architecture]
ONF, "SDN Architecture", June 2014.

[opsawg-firewalls]
Baker, F. and P. Hoffman, "On Firewalls in Internet
Security", draft-ietf-opsawg-firewalls-01 (work in
progress), October 2012.

[registration-inf-dm]
Hyun, S., Jeong, J., Roh, T., Wi, S., and J. Park, "I2NSF
Registration Interface YANG Data Model", draft-hyun-i2nsf-
registration-dm-03
registration-dm-04 (work in progress), March July 2018.

[registration-inf-im]
Hyun, S., Jeong, J., Roh, T., Wi, S., and J. Park, "I2NSF
Registration Interface Information Model", draft-hyun-
i2nsf-registration-interface-im-04
i2nsf-registration-interface-im-05 (work in progress),
March
July 2018.

[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006.

[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the
Network Configuration Protocol (NETCONF)", RFC 6020,
October 2010.

[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
Bierman, "Network Configuration Protocol (NETCONF)",
RFC 6241, June 2011.

[RFC7149] Boucadair, M. and C. Jacquenet, "Software-Defined
Networking: A Perspective from within a Service Provider
Environment", RFC 7149, March 2014.

[RFC7665] Halpern, J. and C. Pignataro, "Service Function Chaining
(SFC) Architecture", RFC 7665, October 2015.

[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, January 2017.

[RFC8192] Hares, S., Lopez, D., Zarny, M., Jacquenet, C., Kumar, R.,
and J. Jeong, "Interface to Network Security Functions
(I2NSF): Problem Statement and Use Cases", RFC 8192, July
2017.

[RFC8300] Quinn, P., Elzur, U., and C. Pignataro, "Network Service
Header (NSH)", RFC 8300, January 2018.

[RFC8329] Lopez, D., Lopez, E., Dunbar, L., Strassner, J., and R.
Kumar, "Framework for Interface to Network Security
Functions", RFC 8329, February 2018.

Appendix A. Changes from draft-ietf-i2nsf-applicability-01 draft-ietf-i2nsf-applicability-02

The following changes have been made from draft-ietf-i2nsf-
applicability-01:
applicability-02:

o In Section 4, it is clarified what types of security policy rules
can be enforced by SDN switches or NSFs in explained how the environment of I2NSF framework with SDN. and SFC can
be combined to support chaining NSFs.

o In Section 4, 6, it is explained what should be done by the Security
Controller in order to divide the enforcement of security policy
rules into the SDN switches and NSFs in how the I2NSF framework with
SDN. can be
implemented based on the NFV reference architecture.

Authors' Addresses

Jaehoon Paul Jeong
Department of Software
Sungkyunkwan University
2066 Seobu-Ro, Jangan-Gu
Suwon, Gyeonggi-Do 16419
Republic of Korea

Phone: +82 31 299 4957
Fax: +82 31 290 7996
EMail: pauljeong@skku.edu
URI: http://iotlab.skku.edu/people-jaehoon-jeong.php

Sangwon Hyun
Department of Software
Sungkyunkwan Computer Engineering
Chosun University
2066 Seobu-Ro, Jangan-Gu
Suwon, Gyeonggi-Do 16419
309 Pilmun-daero, Dong-Gu
Gwangju 61452
Republic of Korea

Phone: +82 31 290 7222
Fax: +82 31 299 6673 62 230 7473
EMail: swhyun77@skku.edu
URI: http://imtl.skku.ac.kr/ shyun@chosun.ac.kr

Tae-Jin Ahn
Korea Telecom
70 Yuseong-Ro, Yuseong-Gu
Daejeon 305-811
Republic of Korea

Phone: +82 42 870 8409
EMail: taejin.ahn@kt.com
Susan Hares
Huawei
7453 Hickory Hill
Saline, MI 48176
USA

Phone: +1-734-604-0332
EMail: shares@ndzh.com

Diego R. Lopez
Telefonica I+D
Jose Manuel Lara, 9
Seville 41013
Spain

Phone: +34 682 051 091
EMail: diego.r.lopez@telefonica.com