< draft-ietf-i2nsf-applicability-11.txt   draft-ietf-i2nsf-applicability-12.txt >
I2NSF Working Group J. Jeong I2NSF Working Group J. Jeong
Internet-Draft Sungkyunkwan University Internet-Draft Sungkyunkwan University
Intended status: Informational S. Hyun Intended status: Informational S. Hyun
Expires: November 17, 2019 Chosun University Expires: December 20, 2019 Chosun University
T. Ahn T. Ahn
Korea Telecom Korea Telecom
S. Hares S. Hares
Huawei Huawei
D. Lopez D. Lopez
Telefonica I+D Telefonica I+D
May 16, 2019 June 18, 2019
Applicability of Interfaces to Network Security Functions to Network- Applicability of Interfaces to Network Security Functions to Network-
Based Security Services Based Security Services
draft-ietf-i2nsf-applicability-11 draft-ietf-i2nsf-applicability-12
Abstract Abstract
This document describes the applicability of Interface to Network This document describes the applicability of Interface to Network
Security Functions (I2NSF) to network-based security services in Security Functions (I2NSF) to network-based security services in
Network Functions Virtualization (NFV) environments, such as Network Functions Virtualization (NFV) environments, such as
firewall, deep packet inspection, or attack mitigation engines. firewall, deep packet inspection, or attack mitigation engines.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 17, 2019. This Internet-Draft will expire on December 20, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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publication of this document. Please review these documents publication of this document. Please review these documents
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. I2NSF Framework . . . . . . . . . . . . . . . . . . . . . . . 5 3. I2NSF Framework . . . . . . . . . . . . . . . . . . . . . . . 5
4. Time-dependent Web Access Control Service . . . . . . . . . . 7 4. Time-dependent Web Access Control Service . . . . . . . . . . 6
5. I2NSF Framework with SFC . . . . . . . . . . . . . . . . . . 10 5. I2NSF Framework with SFC . . . . . . . . . . . . . . . . . . 9
6. I2NSF Framework with SDN . . . . . . . . . . . . . . . . . . 12 6. I2NSF Framework with SDN . . . . . . . . . . . . . . . . . . 11
6.1. Firewall: Centralized Firewall System . . . . . . . . . . 15 6.1. Firewall: Centralized Firewall System . . . . . . . . . . 13
6.2. Deep Packet Inspection: Centralized VoIP/VoLTE Security 6.2. Deep Packet Inspection: Centralized VoIP/VoLTE Security
System . . . . . . . . . . . . . . . . . . . . . . . . . 15 System . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.3. Attack Mitigation: Centralized DDoS-attack Mitigation 6.3. Attack Mitigation: Centralized DDoS-attack Mitigation
System . . . . . . . . . . . . . . . . . . . . . . . . . 15 System . . . . . . . . . . . . . . . . . . . . . . . . . 14
7. I2NSF Framework with NFV . . . . . . . . . . . . . . . . . . 17 7. I2NSF Framework with NFV . . . . . . . . . . . . . . . . . . 15
8. Security Considerations . . . . . . . . . . . . . . . . . . . 19 8. Security Considerations . . . . . . . . . . . . . . . . . . . 17
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 19 10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 18
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 20 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
11.1. Normative References . . . . . . . . . . . . . . . . . . 20 11.1. Normative References . . . . . . . . . . . . . . . . . . 19
11.2. Informative References . . . . . . . . . . . . . . . . . 21 11.2. Informative References . . . . . . . . . . . . . . . . . 20
Appendix A. Changes from draft-ietf-i2nsf-applicability-10 . . . 23 Appendix A. Changes from draft-ietf-i2nsf-applicability-10 . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction 1. Introduction
Interface to Network Security Functions (I2NSF) defines a framework Interface to Network Security Functions (I2NSF) defines a framework
and interfaces for interacting with Network Security Functions and interfaces for interacting with Network Security Functions
(NSFs). Note that an NSF is defined as software that provides a set (NSFs). Note that an NSF is defined as software that provides a set
of security-related services, such as (i) detecting unwanted of security-related services, such as (i) detecting unwanted
activity, (ii) blocking or mitigating the effect of such unwanted activity, (ii) blocking or mitigating the effect of such unwanted
activity in order to fulfil service requirements, and (iii) activity in order to fulfil service requirements, and (iii)
supporting communication stream integrity and confidentiality supporting communication stream integrity and confidentiality
[i2nsf-terminology]. [i2nsf-terminology].
The I2NSF framework allows heterogeneous NSFs developed by different The I2NSF framework allows heterogeneous NSFs developed by different
security solution vendors to be used in the Network Functions security solution vendors to be used in the Network Functions
Virtualization (NFV) environment [ETSI-NFV] by utilizing the Virtualization (NFV) environment [ETSI-NFV] by utilizing the
capabilities of such NSFs through I2NSF interfaces such as Customer- capabilities of such NSFs through I2NSF interfaces such as Customer-
Facing Interface [consumer-facing-inf-dm] and NSF-Facing Interface Facing Interface [consumer-facing-inf-dm] and NSF-Facing Interface
[nsf-facing-inf-dm]. In the I2NSF framework, each NSF initially [nsf-facing-inf-dm]. In the I2NSF framework, each NSF initially
registers the profile of its own capabilities into the Security registers the profile of its own capabilities with the Security
Controller (i.e., network operator management system [RFC8329]) in Controller (i.e., network operator management system [RFC8329]) of
the I2NSF system via Registration Interface [registration-inf-dm] so the I2NSF system via the Registration Interface
that each NSF can be selected and used to enforce a given security [registration-inf-dm]. This registration enables an I2NSF User
policy from I2NSF User (i.e., network security administrator). Note (i.e., network security administrator) to select and use the NSF to
that Developer's Management System (DMS) is management software that enforce a given security policy. Note that Developer's Management
provides a vendor's security service software as a Virtual Network System (DMS) is management software that provides a vendor's security
Function (VNF) in an NFV environment (or middlebox in the legacy service software as a Virtual Network Function (VNF) in an NFV
network) as an NSF, and registers the capabilities of an NSF into environment (or middlebox in the legacy network) as an NSF, and
Security Controller via Registration Interface for a security service registers the capabilities of an NSF into Security Controller via
[RFC8329]. Registration Interface for a security service [RFC8329].
Security Controller is defined as a management component that Security Controller maintains the mapping between a capability and an
contains control plane functions to manage NSFs and facilitate NSF, so it can perform to translate a high-level security policy
information sharing among other components (e.g., NSFs and I2NSF received from I2NSF User to a low-level security policy configured
User) in an I2NSF system [i2nsf-terminology]. Security Controller and enforced in an NSF [policy-translation]. Security Controller can
maintains the mapping between a capability and an NSF, so it can monitor the states and security attacks in NSFs through NSF
perform to translate a high-level security policy received from I2NSF monitoring [nsf-monitoring-dm].
User to a low-level security policy configured and enforced in an NSF
[policy-translation]. Security Controller can monitor the states and
security attacks in NSFs through NSF monitoring [nsf-monitoring-dm].
This document illustrates the applicability of the I2NSF framework This document illustrates the applicability of the I2NSF framework
with four different scenarios: with four different scenarios:
1. The enforcement of time-dependent web access control. 1. The enforcement of time-dependent web access control.
2. The application of I2NSF to a Service Function Chaining (SFC) 2. The application of I2NSF to a Service Function Chaining (SFC)
environment [RFC7665]. environment [RFC7665].
3. The integration of the I2NSF framework with Software-Defined 3. The integration of the I2NSF framework with Software-Defined
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security capabilities, and generates low-level security policies for security capabilities, and generates low-level security policies for
each of the NSFs so that the high-level security policies are each of the NSFs so that the high-level security policies are
eventually enforced by those NSFs [policy-translation]. Finally, the eventually enforced by those NSFs [policy-translation]. Finally, the
Security Controller sends the generated low-level security policies Security Controller sends the generated low-level security policies
to the NSFs via the NSF-Facing Interface [nsf-facing-inf-dm]. to the NSFs via the NSF-Facing Interface [nsf-facing-inf-dm].
As shown in Figure 1, with a Developer's Management System (called As shown in Figure 1, with a Developer's Management System (called
DMS), developers (or vendors) inform the Security Controller of the DMS), developers (or vendors) inform the Security Controller of the
capabilities of the NSFs through the Registration Interface capabilities of the NSFs through the Registration Interface
[registration-inf-dm] for registering (or deregistering) the [registration-inf-dm] for registering (or deregistering) the
corresponding NSFs. Note that an inside attacker at the DMS can corresponding NSFs.
seriously weaken the I2NSF system's security. That is, DMS can be
compromised to attack the Security Controller by providing the
Security Controller with malicious NSFs, and controlling those NSFs
in real time. To deal with this type of threat, the role of the DMS
should be restricted to providing an I2NSF system with the software
package/image for NSF execution, and the DMS should never be able to
access NSFs in online/activated status for the I2NSF system's
security. On the other hand, an access to active NSFs should be
allowed only to the Security Controller, not the DMS during the
provisioning time of those NSFs to the I2NSF system. However, note
that an inside attacker can access the active NSFs, which are being
executed as either VNFs or middleboxes in the I2NSF system, through a
back door (i.e., an IP address and a port number that are known to
the DMS to control an NSF). However, the Security Controller can
detect and prevent inside attacks by monitoring the activities of all
the DMSs as well as the NSFs through the I2NSF NSF monitoring
functionality [nsf-monitoring-dm]. Through the NSF monitoring, the
Security Controller can monitor the activities and states of NSFs,
and then can make a diagnosis to see whether the NSFs are working in
normal conditions or in abnormal conditions including the insider
threat. Note that the monitoring of the DMSs is out of scope for
I2NSF.
The Consumer-Facing Interface can be implemented as an XML file based The Consumer-Facing Interface can be implemented with the Consumer-
on the Consumer-Facing Interface data model [consumer-facing-inf-dm] Facing Interface YANG data model [consumer-facing-inf-dm] using
along with RESTCONF [RFC8040], which befits a web-based user RESTCONF [RFC8040] which befits a web-based user interface for an
interface for an I2NSF User to send a Security Controller a high- I2NSF User to send a Security Controller a high-level security
level security policy. Data models specified by YANG [RFC6020] policy. Data models specified by YANG [RFC6020] describe high-level
describe high-level security policies to be specified by an I2NSF security policies to be specified by an I2NSF User. The data model
User. The data model defined in [consumer-facing-inf-dm] can be used defined in [consumer-facing-inf-dm] can be used for the I2NSF
for the I2NSF Consumer-Facing Interface. Note that an inside Consumer-Facing Interface. Note that an inside attacker at the I2NSF
attacker at the I2NSF User can misuse the I2NSF system so that the User can misuse the I2NSF system so that the network system under the
network system under the I2NSF system is vulnerable to security I2NSF system is vulnerable to security attacks. To handle this type
attacks. To handle this type of threat, the Security Controller of threat, the Security Controller needs to monitor the activities of
needs to monitor the activities of all the I2NSF Users as well as the all the I2NSF Users as well as the NSFs through the I2NSF NSF
NSFs through the I2NSF NSF monitoring functionality monitoring functionality [nsf-monitoring-dm]. Note that the
[nsf-monitoring-dm]. Note that the monitoring of the I2NSF Users is monitoring of the I2NSF Users is out of scope of I2NSF.
out of scope for I2NSF.
The NSF-Facing Interface can be implemented as an XML file based on The NSF-Facing Interface can be implemented with the NSF-Facing
the NSF-Facing Interface YANG data model [nsf-facing-inf-dm] along Interface YANG data model [nsf-facing-inf-dm] using NETCONF [RFC6241]
with NETCONF [RFC6241], which befits a command-line-based remote- which befits a command-line-based remote-procedure call for a
procedure call for a Security Controller to configure an NSF with a Security Controller to configure an NSF with a low-level security
low-level security policy. Data models specified by YANG [RFC6020] policy. Data models specified by YANG [RFC6020] describe low-level
describe low-level security policies for the sake of NSFs, which are security policies for the sake of NSFs, which are translated from the
translated from the high-level security policies by the Security high-level security policies by the Security Controller. The data
Controller. The data model defined in [nsf-facing-inf-dm] can be model defined in [nsf-facing-inf-dm] can be used for the I2NSF NSF-
used for the I2NSF NSF-Facing Interface. Facing Interface.
The Registration Interface can be implemented as an XML file based on The Registration Interface can be implemented with the Registration
the Registration Interface YANG data model [registration-inf-dm] Interface YANG data model [registration-inf-dm] using NETCONF
along with NETCONF [RFC6241], which befits a command-line-based [RFC6241] which befits a command-line-based remote-procedure call for
remote-procedure call for a DMS to send a Security Controller an a DMS to send a Security Controller an NSF's capability information.
NSF's capability information. Data models specified by YANG Data models specified by YANG [RFC6020] describe the registration of
[RFC6020] describe the registration of an NSF's capabilities to an NSF's capabilities to enforce security services at the NSF. The
enforce security services at the NSF. The data model defined in data model defined in [registration-inf-dm] can be used for the I2NSF
[registration-inf-dm] can be used for the I2NSF Registration Registration Interface.
Interface.
Also, the I2NSF framework can enforce multiple chained NSFs for the The I2NSF framework can chain multiple NSFs to implement low-level
low-level security policies by means of SFC techniques for the I2NSF security policies with the SFC architecture [RFC7665].
architecture [RFC7665].
The following sections describe different security service scenarios The following sections describe different security service scenarios
illustrating the applicability of the I2NSF framework. illustrating the applicability of the I2NSF framework.
4. Time-dependent Web Access Control Service 4. Time-dependent Web Access Control Service
This service scenario assumes that an enterprise network This service scenario assumes that an enterprise network
administrator wants to control the staff members' access to a administrator wants to control the staff members' access to a
particular Internet service (e.g., Example.com) during business particular Internet service (e.g., Example.com) during business
hours. The following is an example high-level security policy rule hours. The following is an example high-level security policy rule
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After receiving the high-level security policy, the Security After receiving the high-level security policy, the Security
Controller identifies required security capabilities, e.g., IP Controller identifies required security capabilities, e.g., IP
address and port number inspection capabilities and URL inspection address and port number inspection capabilities and URL inspection
capability. In this scenario, it is assumed that the IP address and capability. In this scenario, it is assumed that the IP address and
port number inspection capabilities are required to check whether a port number inspection capabilities are required to check whether a
received packet is an HTTP packet from a staff member. The URL received packet is an HTTP packet from a staff member. The URL
inspection capability is required to check whether the target URL of inspection capability is required to check whether the target URL of
a received packet is in the Example.com domain or not. a received packet is in the Example.com domain or not.
The Security Controller maintains the security capabilities of each The Security Controller maintains the security capabilities of each
NSF running in the I2NSF system, which have been reported by the active NSF in the I2NSF system, which have been reported by the
Developer's Management System via the Registration interface. Based Developer's Management System via the Registration interface. Based
on this information, the Security Controller identifies NSFs that can on this information, the Security Controller identifies NSFs that can
perform the IP address and port number inspection and URL inspection perform the IP address and port number inspection and URL inspection
[policy-translation]. In this scenario, it is assumed that a [policy-translation]. In this scenario, it is assumed that a
firewall NSF has the IP address and port number inspection firewall NSF has the IP address and port number inspection
capabilities and a web filter NSF has URL inspection capability. capabilities and a web filter NSF has URL inspection capability.
The Security Controller generates low-level security rules for the The Security Controller generates low-level security rules for the
NSFs to perform IP address and port number inspection, URL NSFs to perform IP address and port number inspection, URL
inspection, and time checking. Specifically, the Security Controller inspection, and time checking. Specifically, the Security Controller
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1. A staff member tries to access Example.com during business hours, 1. A staff member tries to access Example.com during business hours,
e.g., 10 AM. e.g., 10 AM.
2. The packet is forwarded from the staff member's device to the 2. The packet is forwarded from the staff member's device to the
firewall, and the firewall checks the source IP address and port firewall, and the firewall checks the source IP address and port
number. Now the firewall identifies the received packet is an number. Now the firewall identifies the received packet is an
HTTP packet from the staff member. HTTP packet from the staff member.
3. The firewall triggers the web filter to further inspect the 3. The firewall triggers the web filter to further inspect the
packet, and the packet is forwarded from the firewall to the web packet, and the packet is forwarded from the firewall to the web
filter. SFC technology can be utilized to support such packet filter. The SFC architecture [RFC7665] can be utilized to
forwarding in the I2NSF framework [RFC7665]. support such packet forwarding in the I2NSF framework.
4. The web filter checks the target URL field of the received 4. The web filter checks the target URL field of the received
packet, and realizes the packet is toward Example.com. The web packet, and realizes the packet is toward Example.com. The web
filter then checks that the current time is in business hours. filter then checks that the current time is in business hours.
If so, the web filter drops the packet, and consequently the If so, the web filter drops the packet, and consequently the
staff member's access to Example.com during business hours is staff member's access to Example.com during business hours is
blocked. blocked.
+------------+ +------------+
| I2NSF User | | I2NSF User |
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with the classification rules over NSF-Facing Interface so that with the classification rules over NSF-Facing Interface so that
relevant traffic packets can follow the SFPs. Also, based on the relevant traffic packets can follow the SFPs. Also, based on the
global view of NSF instances available in the system, the Security global view of NSF instances available in the system, the Security
Controller constructs forwarding tables, which are required for SFFs Controller constructs forwarding tables, which are required for SFFs
to forward a given packet to the next NSF over the SFP, and to forward a given packet to the next NSF over the SFP, and
configures SFFs with those forwarding tables over NSF-Facing configures SFFs with those forwarding tables over NSF-Facing
Interface. Interface.
To trigger an advanced security action in the I2NSF architecture, the To trigger an advanced security action in the I2NSF architecture, the
current NSF appends metadata describing the security capability current NSF appends metadata describing the security capability
required for the advanced action to the suspicious packet to the required to the suspicious packet via a network service header (NSH)
network service header (NSH) of the packet [RFC8300]. It then sends [RFC8300]. It then sends the packet to the classifier. Based on the
the packet to the classifier. Based on the metadata information, the metadata information, the classifier searches an SFP which includes
classifier searches an SFP which includes an NSF with the required an NSF with the required security capability, changes the SFP-related
security capability, changes the SFP-related information (e.g., information (e.g., service path identifier and service index
service path identifier and service index [RFC8300]) of the packet [RFC8300]) of the packet with the new SFP that has been found, and
with the new SFP that has been found, and then forwards the packet to then forwards the packet to the SFF. When receiving the packet, the
the SFF. When receiving the packet, the SFF checks the SFP-related SFF checks the SFP-related information such as the service path
information such as the service path identifier and service index identifier and service index contained in the packet and forwards the
contained in the packet and forwards the packet to the next NSF on packet to the next NSF on the SFP of the packet, according to its
the SFP of the packet, according to its forwarding table. forwarding table.
+------------+ +------------+
| I2NSF User | | I2NSF User |
+------------+ +------------+
^ ^
| Consumer-Facing Interface | Consumer-Facing Interface
v v
+-------------------+ Registration +-----------------------+ +-------------------+ Registration +-----------------------+
|Security Controller|<-------------------->|Developer's Mgmt System| |Security Controller|<-------------------->|Developer's Mgmt System|
+-------------------+ Interface +-----------------------+ +-------------------+ Interface +-----------------------+
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both SDN forwarding elements and a firewall NSF is more efficient both SDN forwarding elements and a firewall NSF is more efficient
than a firewall where SDN forwarding elements forward all the packets than a firewall where SDN forwarding elements forward all the packets
to a firewall NSF for packet filtering. This is because packets to to a firewall NSF for packet filtering. This is because packets to
be filtered out can be early dropped by SDN forwarding elements be filtered out can be early dropped by SDN forwarding elements
without consuming further network bandwidth due to the forwarding of without consuming further network bandwidth due to the forwarding of
the packets to the firewall NSF. the packets to the firewall NSF.
Figure 4 shows an I2NSF framework [RFC8329] with SDN networks to Figure 4 shows an I2NSF framework [RFC8329] with SDN networks to
support network-based security services. In this system, the support network-based security services. In this system, the
enforcement of security policy rules is divided into the SDN enforcement of security policy rules is divided into the SDN
forwarding elements (e.g., switch running as either a hardware middle forwarding elements (e.g., a switch running as either a hardware
box or a software virtual switch) and NSFs (e.g., firewall running in middle box or a software virtual switch) and NSFs (e.g., a firewall
a form of a virtual network function (VNF) [ETSI-NFV]). Note that running in a form of a VNF [ETSI-NFV]). Note that NSFs are created
NSFs are created or removed by the NFV Management and Orchestration or removed by the NFV Management and Orchestration (MANO)
(MANO) [ETSI-NFV-MANO], performing the life-cycle management of NSFs [ETSI-NFV-MANO], performing the lifecycle management of NSFs as VNFs.
as VNFs. Refer to Section 7 for the detailed discussion of the NSF Refer to Section 7 for the detailed discussion of the NSF lifecycle
life-cycle management in the NFV MANO for I2NSF. SDN forwarding management in the NFV MANO for I2NSF. For security policy
elements enforce simple packet filtering rules that can be translated enforcement (e.g., packet filtering), the Security Controller
into their packet forwarding rules, whereas NSFs enforce complicated instructs the SDN Controller via NSF-Facing Interface so that SDN
NSF-related security rules requiring the security capabilities of the forwarding elements can perform the required security services with
NSFs. Note that SDN packet forwarding rules are for packet flow tables under the supervision of the SDN Controller.
forwarding or filtering by flow table entries at SDN forwarding
elements, and NSF rules are for security enforcement at NSFs (e.g.,
firewall). Thus, simple firewall rules can be enforced by SDN packet
forwarding rules at SDN forwarding elements (e.g., switches). For
the tasks for security enforcement (e.g., packet filtering), the
Security Controller instructs the SDN Controller via NSF-Facing
Interface so that SDN forwarding elements can perform the required
security services with flow tables under the supervision of the SDN
Controller.
As an example, let us consider two different types of security rules: As an example, let us consider two different types of security rules:
Rule A is a simple packet filtering rule that checks only the IP Rule A is a simple packet filtering rule that checks only the IP
address and port number of a given packet, whereas rule B is a time- address and port number of a given packet, whereas rule B is a time-
consuming packet inspection rule for analyzing whether an attached consuming packet inspection rule for analyzing whether an attached
file being transmitted over a flow of packets contains malware. Rule file being transmitted over a flow of packets contains malware. Rule
A can be translated into packet forwarding rules of SDN forwarding A can be translated into packet forwarding rules of SDN forwarding
elements and thus be enforced by these elements. In contrast, rule B elements and thus be enforced by these elements. In contrast, rule B
cannot be enforced by forwarding elements, but it has to be enforced cannot be enforced by forwarding elements, but it has to be enforced
by NSFs with anti-malware capability. Specifically, a flow of by NSFs with anti-malware capability. Specifically, a flow of
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rules requires security capabilities that can be provided by SDN rules requires security capabilities that can be provided by SDN
forwarding elements, then the Security Controller instructs the SDN forwarding elements, then the Security Controller instructs the SDN
Controller via NSF-Facing Interface so that SDN forwarding elements Controller via NSF-Facing Interface so that SDN forwarding elements
can enforce those security policy rules with flow tables under the can enforce those security policy rules with flow tables under the
supervision of the SDN Controller. Or if some rules require security supervision of the SDN Controller. Or if some rules require security
capabilities that cannot be provided by SDN forwarding elements but capabilities that cannot be provided by SDN forwarding elements but
by NSFs, then the Security Controller instructs relevant NSFs to by NSFs, then the Security Controller instructs relevant NSFs to
enforce those rules. enforce those rules.
The distinction between software-based SDN forwarding elements and The distinction between software-based SDN forwarding elements and
NSFs, which can both run as virtual network functions (VNFs), may be NSFs, which can both run as VNFs, may be necessary for some
necessary for some management purposes in this system. Note that an management purposes in this system. Note that an SDN forwarding
SDN forwarding element (i.e., switch) is a specific type of VNF element (i.e., switch) is a specific type of VNF rather than an NSF
rather than an NSF because an NSF is for security services rather because an NSF is for security services rather than for packet
than for packet forwarding. For this distinction, we can take forwarding. For this distinction, we can take advantage of the NFV
advantage of the NFV MANO where there is a subsystem that maintains MANO where there is a subsystem that maintains the descriptions of
the descriptions of the capabilities each VNF can offer the capabilities each VNF can offer [ETSI-NFV-MANO]. This subsystem
[ETSI-NFV-MANO]. This subsystem can determine whether a given can determine whether a given software element (VNF instance) is an
software element (VNF instance) is an NSF or a virtualized SDN NSF or a virtualized SDN switch. For example, if a VNF instance has
switch. For example, if a VNF instance has anti-malware capability anti-malware capability according to the description of the VNF, it
according to the description of the VNF, it could be considered as an could be considered as an NSF. A VNF onboarding system
NSF. A VNF onboarding system [VNF-ONBOARDING] can be used as such a [VNF-ONBOARDING] can be used as such a subsystem that maintains the
subsystem that maintains the descriptions of each VNF to tell whether descriptions of each VNF to tell whether a VNF instance is for an NSF
a VNF instance is for an NSF or for a virtualized SDN switch. or for a virtualized SDN switch.
For the support of SFC in the I2NSF framework with SDN, as shown in For the support of SFC in the I2NSF framework with SDN, as shown in
Figure 4, network forwarding elements (e.g., switch) can play the Figure 4, network forwarding elements (e.g., switch) can play the
role of either SFC Classifier or SFF, which are explained in role of either SFC Classifier or SFF, which are explained in
Section 5. Classifier and SFF have an NSF-Facing Interface with Section 5. Classifier and SFF have an NSF-Facing Interface with
Security Controller. This interface is used to update security Security Controller. This interface is used to update security
service function chaining information for traffic flows. For service function chaining information for traffic flows. For
example, when it needs to update an SFP for a traffic flow in an SDN example, when it needs to update an SFP for a traffic flow in an SDN
network, as shown in Figure 4, SFF (denoted as Switch-3) asks network, as shown in Figure 4, SFF (denoted as Switch-3) asks
Security Controller to update the SFP for the traffic flow (needing Security Controller to update the SFP for the traffic flow (needing
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to rapidly and flexibly respond to the amount of service requests by to rapidly and flexibly respond to the amount of service requests by
dynamically increasing or decreasing the number of NSF instances. dynamically increasing or decreasing the number of NSF instances.
Moreover, NFV technology facilitates flexibly including or excluding Moreover, NFV technology facilitates flexibly including or excluding
NSFs from multiple security solution vendors according to the changes NSFs from multiple security solution vendors according to the changes
on security requirements. In order to take advantages of the NFV on security requirements. In order to take advantages of the NFV
technology, the I2NSF framework can be implemented on top of an NFV technology, the I2NSF framework can be implemented on top of an NFV
infrastructure as show in Figure 5. infrastructure as show in Figure 5.
Figure 5 shows an I2NSF framework implementation based on the NFV Figure 5 shows an I2NSF framework implementation based on the NFV
reference architecture that the European Telecommunications Standards reference architecture that the European Telecommunications Standards
Institute (ETSI) defines [ETSI-NFV]. The NSFs are deployed as Institute (ETSI) defines [ETSI-NFV]. The NSFs are deployed as VNFs
virtual network functions (VNFs) in Figure 5. The Developer's in Figure 5. The Developer's Management System (DMS) in the I2NSF
Management System (DMS) in the I2NSF framework is responsible for framework is responsible for registering capability information of
registering capability information of NSFs into the Security NSFs into the Security Controller. However, those NSFs are created
Controller. However, those NSFs are created or removed by a virtual or removed by a virtual network function manager (VNFM) in the NFV
network functions manager (VNFM) in the NFV MANO that performs the MANO that performs the lifecycle management of VNFs. Note that the
life-cycle management of VNFs. Note that the life-cycle management lifecycle management of VNFs is out of scope of I2NSF. The Security
of VNFs are out of scope for I2NSF. The Security Controller controls Controller controls and monitors the configurations (e.g., function
and monitors the configurations (e.g., function parameters and parameters and security policy rules) of VNFs via the NSF-Facing
security policy rules) of VNFs via NSF-Facing Interface along with Interface along with the NSF monitoring capability
NSF monitoring capability [nsf-facing-inf-dm][nsf-monitoring-dm]. [nsf-facing-inf-dm][nsf-monitoring-dm]. Both the DMS and Security
Both the DMS and Security Controller can be implemented as the Controller can be implemented as the Element Managements (EMs) in the
Element Managements (EMs) in the NFV architecture. Finally, the NFV architecture. Finally, the I2NSF User can be implemented as OSS/
I2NSF User can be implemented as OSS/BSS (Operational Support BSS (Operational Support Systems/Business Support Systems) in the NFV
Systems/Business Support Systems) in the NFV architecture that architecture that provides interfaces for users in the NFV system.
provides interfaces for users in the NFV system.
The operation procedure in the I2NSF framework based on the NFV The operation procedure in the I2NSF framework based on the NFV
architecture is as follows: architecture is as follows:
1. The VNFM has a set of virtual machine (VM) images of NSFs, and 1. The VNFM has a set of virtual machine (VM) images of NSFs, and
each VM image can be used to create an NSF instance that provides each VM image can be used to create an NSF instance that provides
a set of security capabilities. The DMS initially registers a a set of security capabilities. The DMS initially registers a
mapping table of the ID of each VM image and the set of mapping table of the ID of each VM image and the set of
capabilities that can be provided by an NSF instance created from capabilities that can be provided by an NSF instance created from
the VM image into the Security Controller. the VM image into the Security Controller.
skipping to change at page 19, line 33 skipping to change at page 17, line 33
Ve-Vnfm interface between the DMS and VNFM, as shown in Figure 5. Ve-Vnfm interface between the DMS and VNFM, as shown in Figure 5.
8. Security Considerations 8. Security Considerations
The same security considerations for the I2NSF framework [RFC8329] The same security considerations for the I2NSF framework [RFC8329]
are applicable to this document. are applicable to this document.
This document shares all the security issues of SDN that are This document shares all the security issues of SDN that are
specified in the "Security Considerations" section of [ITU-T.Y.3300]. specified in the "Security Considerations" section of [ITU-T.Y.3300].
Note that an inside attacker (or supply chain attacker) at the DMS
can seriously weaken the I2NSF system's security. Note that a
malicious NSF provider (as a DMS) is relevant to an insider attack,
and a compromised NSF provider is relevant to a supply chain attack.
Also, note that a malicious (or compromised) DMS sending the wrong
NSF may not modify the original code of the NSF but may alter the
sent NSF as an instant. As a result, a malicious (or compromised)
DMS can attack the Security Controller by providing the Security
Controller with malicious (or compromised) NSFs, and controlling
those NSFs in real time. Also, an unwitting DMS vendor could be
compromised and their infrastructure could be coerced into
distributing modified NSFs. To deal with these types of threats, the
role of the DMS should be restricted to providing an I2NSF system
with the software package/image for NSF execution, and the DMS should
never be able to access NSFs in activated status for the I2NSF
system's security. On the other hand, an access to active NSFs
should be allowed only to the Security Controller, not the DMS during
the provisioning time of those NSFs to the I2NSF system. However,
note that an inside attacker (or supply chain attacker) can access
the active NSFs, which are being executed as either VNFs or
middleboxes in the I2NSF system, through a back door (i.e., an IP
address and a port number that are known to the DMS to control an
NSF). However, the Security Controller may detect and prevent those
inside attacks (or supply chain attacks) by monitoring the activities
of all the DMSs as well as the NSFs through the I2NSF NSF Monitoring
Interface [nsf-monitoring-dm] as part of the I2NSF NSF-Facing
Interface. Through the NSF Monitoring Interface, the Security
Controller can monitor the activities and states of NSFs, and then
can make a diagnosis to see whether the NSFs are working in normal
conditions or in abnormal conditions including the insider threats
(or supply chain threats). Note that the monitoring of the DMSs is
out of scope of I2NSF. However, as a general caution, a mitigation
strategy for insider attacks and supply chain attacks is not to use
an NSF without prior testing for an automated security action in the
I2NSF system.
9. Acknowledgments 9. Acknowledgments
This work was supported by Institute for Information & communications This work was supported by Institute for Information & communications
Technology Promotion (IITP) grant funded by the Korea government Technology Promotion (IITP) grant funded by the Korea government
(MSIP) (No.R-20160222-002755, Cloud based Security Intelligence (MSIP) (No.R-20160222-002755, Cloud based Security Intelligence
Technology Development for the Customized Security Service Technology Development for the Customized Security Service
Provisioning). Provisioning).
This work has been partially supported by the European Commission This work has been partially supported by the European Commission
under Horizon 2020 grant agreement no. 700199 "Securing against under Horizon 2020 grant agreement no. 700199 "Securing against
skipping to change at page 21, line 37 skipping to change at page 20, line 27
11.2. Informative References 11.2. Informative References
[AVANT-GUARD] [AVANT-GUARD]
Shin, S., Yegneswaran, V., Porras, P., and G. Gu, "AVANT- Shin, S., Yegneswaran, V., Porras, P., and G. Gu, "AVANT-
GUARD: Scalable and Vigilant Switch Flow Management in GUARD: Scalable and Vigilant Switch Flow Management in
Software-Defined Networks", ACM CCS, November 2013. Software-Defined Networks", ACM CCS, November 2013.
[consumer-facing-inf-dm] [consumer-facing-inf-dm]
Jeong, J., Kim, E., Ahn, T., Kumar, R., and S. Hares, Jeong, J., Kim, E., Ahn, T., Kumar, R., and S. Hares,
"I2NSF Consumer-Facing Interface YANG Data Model", draft- "I2NSF Consumer-Facing Interface YANG Data Model", draft-
ietf-i2nsf-consumer-facing-interface-dm-04 (work in ietf-i2nsf-consumer-facing-interface-dm-05 (work in
progress), April 2019. progress), June 2019.
[ETSI-NFV-MANO] [ETSI-NFV-MANO]
"Network Functions Virtualisation (NFV); Management and "Network Functions Virtualisation (NFV); Management and
Orchestration", Available: Orchestration", Available:
https://www.etsi.org/deliver/etsi_gs/nfv- https://www.etsi.org/deliver/etsi_gs/nfv-
man/001_099/001/01.01.01_60/gs_nfv-man001v010101p.pdf, man/001_099/001/01.01.01_60/gs_nfv-man001v010101p.pdf,
December 2014. December 2014.
[i2nsf-terminology] [i2nsf-terminology]
Hares, S., Strassner, J., Lopez, D., Xia, L., and H. Hares, S., Strassner, J., Lopez, D., Xia, L., and H.
skipping to change at page 22, line 12 skipping to change at page 20, line 50
Terminology", draft-ietf-i2nsf-terminology-07 (work in Terminology", draft-ietf-i2nsf-terminology-07 (work in
progress), January 2019. progress), January 2019.
[ITU-T.X.800] [ITU-T.X.800]
"Security Architecture for Open Systems Interconnection "Security Architecture for Open Systems Interconnection
for CCITT Applications", March 1991. for CCITT Applications", March 1991.
[nsf-facing-inf-dm] [nsf-facing-inf-dm]
Kim, J., Jeong, J., Park, J., Hares, S., and Q. Lin, Kim, J., Jeong, J., Park, J., Hares, S., and Q. Lin,
"I2NSF Network Security Function-Facing Interface YANG "I2NSF Network Security Function-Facing Interface YANG
Data Model", draft-ietf-i2nsf-nsf-facing-interface-dm-05 Data Model", draft-ietf-i2nsf-nsf-facing-interface-dm-06
(work in progress), March 2019. (work in progress), June 2019.
[nsf-monitoring-dm] [nsf-monitoring-dm]
Jeong, J., Chung, C., Hares, S., Xia, L., and H. Birkholz, Jeong, J., Chung, C., Hares, S., Xia, L., and H. Birkholz,
"I2NSF NSF Monitoring YANG Data Model", draft-ietf-i2nsf- "I2NSF NSF Monitoring YANG Data Model", draft-ietf-i2nsf-
nsf-monitoring-data-model-00 (work in progress), March nsf-monitoring-data-model-00 (work in progress), March
2019. 2019.
[opsawg-firewalls] [opsawg-firewalls]
Baker, F. and P. Hoffman, "On Firewalls in Internet Baker, F. and P. Hoffman, "On Firewalls in Internet
Security", draft-ietf-opsawg-firewalls-01 (work in Security", draft-ietf-opsawg-firewalls-01 (work in
skipping to change at page 22, line 35 skipping to change at page 21, line 25
[policy-translation] [policy-translation]
Yang, J., Jeong, J., and J. Kim, "Security Policy Yang, J., Jeong, J., and J. Kim, "Security Policy
Translation in Interface to Network Security Functions", Translation in Interface to Network Security Functions",
draft-yang-i2nsf-security-policy-translation-03 (work in draft-yang-i2nsf-security-policy-translation-03 (work in
progress), March 2019. progress), March 2019.
[registration-inf-dm] [registration-inf-dm]
Hyun, S., Jeong, J., Roh, T., Wi, S., and J. Park, "I2NSF Hyun, S., Jeong, J., Roh, T., Wi, S., and J. Park, "I2NSF
Registration Interface YANG Data Model", draft-ietf-i2nsf- Registration Interface YANG Data Model", draft-ietf-i2nsf-
registration-interface-dm-03 (work in progress), March registration-interface-dm-04 (work in progress), June
2019. 2019.
[VNF-ONBOARDING] [VNF-ONBOARDING]
"VNF Onboarding", Available: "VNF Onboarding", Available:
https://wiki.opnfv.org/display/mano/VNF+Onboarding, https://wiki.opnfv.org/display/mano/VNF+Onboarding,
November 2016. November 2016.
Appendix A. Changes from draft-ietf-i2nsf-applicability-10 Appendix A. Changes from draft-ietf-i2nsf-applicability-10
The following changes have been made from draft-ietf-i2nsf- The following changes have been made from draft-ietf-i2nsf-
applicability-10: applicability-11:
o In Section 1, "Network Security Function (NSF)" is replaced with o This version has reflected further questions and comments from
"an NSF" because the abbreviation of "Network Security Function" Roman Danyliw who is a Security Area Director.
is defined as "NSF" in the previous sentence.
o In Section 2, a typo in "funcional block" is corrected as o The security issues and discussion related to Developer's
"functional block". Management System (DMS) are moved to Section 8. The monitoring of
DMSs is out of scope of I2NSF.
o Some typos are corrected.
Authors' Addresses Authors' Addresses
Jaehoon Paul Jeong Jaehoon Paul Jeong
Department of Software Department of Computer Science and Engineering
Sungkyunkwan University Sungkyunkwan University
2066 Seobu-Ro, Jangan-Gu 2066 Seobu-Ro, Jangan-Gu
Suwon, Gyeonggi-Do 16419 Suwon, Gyeonggi-Do 16419
Republic of Korea Republic of Korea
Phone: +82 31 299 4957 Phone: +82 31 299 4957
Fax: +82 31 290 7996 Fax: +82 31 290 7996
EMail: pauljeong@skku.edu EMail: pauljeong@skku.edu
URI: http://iotlab.skku.edu/people-jaehoon-jeong.php URI: http://iotlab.skku.edu/people-jaehoon-jeong.php
 End of changes. 28 change blocks. 
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