--- 1/draft-ietf-i2nsf-applicability-09.txt 2019-05-02 02:13:13.191989579 -0700 +++ 2/draft-ietf-i2nsf-applicability-10.txt 2019-05-02 02:13:13.243990892 -0700 @@ -1,26 +1,26 @@ I2NSF Working Group J. Jeong Internet-Draft Sungkyunkwan University Intended status: Informational S. Hyun -Expires: September 12, 2019 Chosun University +Expires: November 3, 2019 Chosun University T. Ahn Korea Telecom S. Hares Huawei D. Lopez Telefonica I+D - March 11, 2019 + May 2, 2019 Applicability of Interfaces to Network Security Functions to Network- Based Security Services - draft-ietf-i2nsf-applicability-09 + draft-ietf-i2nsf-applicability-10 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 @@ -30,21 +30,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on September 12, 2019. + This Internet-Draft will expire on November 3, 2019. Copyright Notice Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -52,58 +52,76 @@ to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. I2NSF Framework . . . . . . . . . . . . . . . . . . . . . . . 5 - 4. Time-dependent Web Access Control Service . . . . . . . . . . 6 - 5. I2NSF Framework with SFC . . . . . . . . . . . . . . . . . . 8 - 6. I2NSF Framework with SDN . . . . . . . . . . . . . . . . . . 10 - 6.1. Firewall: Centralized Firewall System . . . . . . . . . . 13 + 4. Time-dependent Web Access Control Service . . . . . . . . . . 7 + 5. I2NSF Framework with SFC . . . . . . . . . . . . . . . . . . 10 + 6. I2NSF Framework with SDN . . . . . . . . . . . . . . . . . . 12 + 6.1. Firewall: Centralized Firewall System . . . . . . . . . . 15 6.2. Deep Packet Inspection: Centralized VoIP/VoLTE Security - System . . . . . . . . . . . . . . . . . . . . . . . . . 14 + System . . . . . . . . . . . . . . . . . . . . . . . . . 15 6.3. Attack Mitigation: Centralized DDoS-attack Mitigation - System . . . . . . . . . . . . . . . . . . . . . . . . . 16 - 7. I2NSF Framework with NFV . . . . . . . . . . . . . . . . . . 19 - 8. Security Considerations . . . . . . . . . . . . . . . . . . . 20 - 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20 - 10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 21 - 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 21 - 11.1. Normative References . . . . . . . . . . . . . . . . . . 21 - 11.2. Informative References . . . . . . . . . . . . . . . . . 22 - Appendix A. Changes from draft-ietf-i2nsf-applicability-08 . . . 25 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25 + System . . . . . . . . . . . . . . . . . . . . . . . . . 15 + 7. I2NSF Framework with NFV . . . . . . . . . . . . . . . . . . 17 + 8. Security Considerations . . . . . . . . . . . . . . . . . . . 19 + 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19 + 10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 19 + 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 20 + 11.1. Normative References . . . . . . . . . . . . . . . . . . 20 + 11.2. Informative References . . . . . . . . . . . . . . . . . 21 + Appendix A. Changes from draft-ietf-i2nsf-applicability-09 . . . 23 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 1. Introduction Interface to Network Security Functions (I2NSF) defines a framework and interfaces for interacting with Network Security Functions - (NSFs). Note that Network Security Function (NSF) is defined as a - funcional block for a security service within an I2NSF framework that - has well-defined I2NSF NSF-facing interface and other external - interfaces and well-defined functional behavior [NFV-Terminology]. + (NSFs). Note that Network Security Function (NSF) is defined as + software that provides a set of security-related services, such as + (i) detecting unwanted activity, (ii) blocking or mitigating the + effect of such unwanted activity in order to fulfil service + requirements, and (iii) supporting communication stream integrity and + confidentiality [i2nsf-terminology]. The I2NSF framework allows heterogeneous NSFs developed by different security solution vendors to be used in the Network Functions Virtualization (NFV) environment [ETSI-NFV] 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 is validated by the I2NSF User - (also called I2NSF Client) that a system administrator (as a user) is - employing, so that the system administrator can request security - services through the Security Controller. + capabilities of such NSFs through I2NSF interfaces such as Customer- + Facing Interface [consumer-facing-inf-dm] and NSF-Facing Interface + [nsf-facing-inf-dm]. In the I2NSF framework, each NSF initially + registers the profile of its own capabilities into the Security + Controller (i.e., network operator management system [RFC8329]) in + the I2NSF system via Registration Interface [registration-inf-dm] so + that each NSF can be selected and used to enforce a given security + policy from I2NSF User (i.e., network security administrator). Note + that Developer's Management System (DMS) is management software that + provides a vendor's security service software as a Virtual Network + Function (VNF) in an NFV environment (or middlebox in the legacy + network) as an NSF, and registers the capabilities of an NSF into + Security Controller via Registration Interface for a security service + [RFC8329]. + + Security Controller is defined as a management component that + contains control plane functions to manage NSFs and facilitate + information sharing among other components (e.g., NSFs and I2NSF + User) in an I2NSF system [i2nsf-terminology]. Security Controller + maintains the mapping between a capability and an NSF, so it can + perform to translate a high-level security policy received from I2NSF + 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 with four different scenarios: 1. The enforcement of time-dependent web access control. 2. The application of I2NSF to a Service Function Chaining (SFC) environment [RFC7665]. 3. The integration of the I2NSF framework with Software-Defined @@ -115,41 +133,41 @@ 4. The use of Network Functions Virtualization (NFV) [ETSI-NFV] as a supporting technology. The implementation of I2NSF in these scenarios has allowed us to verify the applicability and effectiveness of the I2NSF framework for a variety of use cases. 2. Terminology This document uses the terminology described in [RFC7665], [RFC7149], - [ITU-T.Y.3300], [ONF-OpenFlow], [ONF-SDN-Architecture], - [ITU-T.X.1252], [ITU-T.X.800], [NFV-Terminology], [RFC8329], - [i2nsf-terminology], [consumer-facing-inf-dm], [i2nsf-nsf-cap-im], - [nsf-facing-inf-dm], [registration-inf-dm], and - [nsf-triggered-steering]. In addition, the following terms are - defined below: + [ITU-T.Y.3300], [ONF-SDN-Architecture], [ITU-T.X.800], + + [NFV-Terminology], [RFC8329], and [i2nsf-terminology]. 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 Network Function: A funcional block within a network infrastructure that has well-defined external interfaces and well- defined functional behavior [NFV-Terminology]. - o Network Security Function (NSF): A funcional block within a - security service within a network infrastructure that has well- - defined external interfaces and well-defined functional - behavior[NFV-Terminology]. + o Network Security Function (NSF): Software that provides a set of + security-related services. Examples include detecting unwanted + activity and blocking or mitigating the effect of such unwanted + activity in order to fulfil service requirements. The NSF can + also help in supporting communication stream integrity and + confidentiality [i2nsf-terminology]. o Network Functions Virtualization (NFV): A principle of separating network functions (or network security functions) from the hardware they run on by using virtual hardware abstraction [NFV-Terminology]. o Service Function Chaining (SFC): The execution of an ordered set of abstract service functions (i.e., network functions) according to ordering constraints that must be applied to packets, frames, and flows selected as a result of classification. The implied @@ -205,167 +223,207 @@ [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 [policy-translation]. Finally, the Security Controller sends the generated low-level security policies - to the NSFs [i2nsf-nsf-cap-im][nsf-facing-inf-dm]. + to the NSFs via the NSF-Facing Interface [nsf-facing-inf-dm]. - The Security Controller requests NSFs to perform low-level security - services via the NSF-Facing Interface. As shown in Figure 1, with a - Developer's Management System (DMS), developers (or vendors) inform - the Security Controller of the capabilities of the NSFs through the - I2NSF Registration Interface [registration-inf-dm] for registering - (or deregistering) the corresponding NSFs. Note that an inside - attacker at the DMS can seriously weaken the I2NSF system's security. - 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 running (online) NSFs should be allowed - only to the Security Controller, not the DMS. Also, the Security - Controller can detect and prevent inside attacks by monitoring the - activity of all the DMSs as well as the NSFs through the I2NSF NSF - monitoring functionality [nsf-monitoring-dm]. + As shown in Figure 1, with a Developer's Management System (called + DMS), developers (or vendors) inform the Security Controller of the + capabilities of the NSFs through the Registration Interface + [registration-inf-dm] for registering (or deregistering) the + corresponding NSFs. Note that an inside attacker at the DMS can + 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 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. + The Consumer-Facing Interface can be implemented as an XML file based + on the Consumer-Facing Interface data model [consumer-facing-inf-dm] + along with RESTCONF [RFC8040], which befits a web-based user + interface for an I2NSF User to send a Security Controller a high- + level security policy. 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. Note that an inside + attacker at the I2NSF User can misuse the I2NSF system so that the + network system under the I2NSF system is vulnerable to security + attacks. To handle this type of threat, the Security Controller + needs to monitor the activities of all the I2NSF Users as well as the + NSFs through the I2NSF NSF monitoring functionality + [nsf-monitoring-dm]. Note that the monitoring of the I2NSF Users is + out of scope for I2NSF. - The NSF-Facing Interface between the 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 + The NSF-Facing Interface can be implemented as an XML file based on + the NSF-Facing Interface YANG data model [nsf-facing-inf-dm] along + with NETCONF [RFC6241], which befits a command-line-based remote- + procedure call for a Security Controller to configure an NSF with a + low-level security policy. Data models specified by YANG [RFC6020] + 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 Management System can be implemented by RESTCONF - [RFC8040]. The data model defined in [registration-inf-dm] can be - used for the I2NSF Registration Interface. + The Registration Interface can be implemented as an XML file based on + the Registration Interface YANG data model [registration-inf-dm] + along with NETCONF [RFC6241], which befits a command-line-based + remote-procedure call for a DMS to send a Security Controller an + NSF's capability information. Data models specified by YANG + [RFC6020] describe the registration of an NSF's capabilities to + enforce security services at the NSF. 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 SFC techniques for the I2NSF - architecture described in [nsf-triggered-steering]. + architecture [RFC7665]. The following sections describe different security service scenarios illustrating the applicability of the I2NSF framework. 4. Time-dependent Web Access Control Service This service scenario assumes that an enterprise network administrator wants to control the staff members' access to a particular Internet service (e.g., Example.com) during business hours. The following is an example high-level security policy rule for a web filter that the administrator requests: Block the staff - members' access to Example.com from 9 AM to 6 PM. Figure 2 is an - example XML code for this web filter: + members' access to Example.com from 9 AM (i.e., 09:00) to 6 PM (i.e., + 18:00) by dropping their packets. Figure 2 is an example XML code + for this web filter that is sent from the I2NSF User to the Security + Controller via the Consumer-Facing Interface + [consumer-facing-inf-dm]: - - block_website - - Staff_Member's_PC - Example.com - 9:00AM - -6:00PM - - block - + + + block_website + + block_website_during_working_hours + + + 09:00 + 18:00 + + + + + + Staff_Member's_PC + + + + + Example.com + + + + + drop + + + Figure 2: An XML Example for Time-based Web-filter - The security policy name is "block_website" with the tag "name". The - filtering condition has the source group "Staff_Member's_PC" with the - tag "src", the destination website "Example.com" with the tag "dest", - the filtering start time is the time "9:00AM" with the tag " time- - span-start", and the filtering end time is the time "6:00PM" with the - tag "time-span-end". The action is to "block" the packets satisfying - the above condition, that is, to drop those packets. + The security policy name is "block_website" with the tag "policy- + name", and the security policy rule name is + "block_website_during_working_hours" with the tag "rule-name". The + filtering event has the time span where the filtering begin time is + the time "09:00" (i.e., 9:00AM) with the tag "begin-time", and the + filtering end time is the time "18:00" (i.e., 6:00PM) with the tag + "end-time". The filtering condition has the source target of + "Staff_Member's_PC" with the tag "src-target", the destination target + of a website "Example.com" with the tag "dest-target". The action is + to "drop" the packets satisfying the above event and condition with + the tag "primary-action". After receiving the high-level security policy, the Security Controller identifies required security 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 in the Example.com domain 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 Registration interface. Based on this information, the Security Controller identifies NSFs that can perform the IP address and port number inspection and URL inspection - [policy-translation]. 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. + [policy-translation]. In this scenario, it is assumed that a + firewall NSF has the IP address and port number inspection + capabilities and a web filter NSF 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 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 check that the target URL field of a received packet is equal to Example.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. + of the IP address and port number inspection to the firewall NSF and + the low-level rules for URL inspection to the web filter NSF. 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 Example.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. SFC technology can be utilized to support such packet - forwarding in the I2NSF framework [nsf-triggered-steering]. + forwarding in the I2NSF framework [RFC7665]. 4. The web filter checks the target URL field of the received packet, and realizes the packet is toward Example.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 Example.com during business hours is blocked. -5. I2NSF Framework with SFC - - In the I2NSF architecture, an NSF can trigger an advanced security - action (e.g., DPI or DDoS attack mitigation) on a packet based on the - result of its own security inspection of the packet. For example, a - firewall triggers further inspection of a suspicious packet with DPI. - For this advanced security action to be fulfilled, the suspicious - packet should be forwarded from the current NSF to the successor NSF. - SFC [RFC7665] is a technology that enables this advanced security - action by steering a packet with multiple service functions (e.g., - NSFs), and this technology can be utilized by the I2NSF architecture - to support the advanced security action. - +------------+ | I2NSF User | +------------+ ^ | Consumer-Facing Interface v +-------------------+ Registration +-----------------------+ |Security Controller|<-------------------->|Developer's Mgmt System| +-------------------+ Interface +-----------------------+ ^ ^ @@ -384,20 +442,33 @@ | . | . | . | +-----------------------+ ------>| NSF-n | |(DDoS-Attack Mitigator)| +-----------------------+ Figure 3: An I2NSF Framework with SFC +5. I2NSF Framework with SFC + + In the I2NSF architecture, an NSF can trigger an advanced security + action (e.g., DPI or DDoS attack mitigation) on a packet based on the + result of its own security inspection of the packet. For example, a + firewall triggers further inspection of a suspicious packet with DPI. + For this advanced security action to be fulfilled, the suspicious + packet should be forwarded from the current NSF to the successor NSF. + SFC [RFC7665] is a technology that enables this advanced security + action by steering a packet with multiple service functions (e.g., + NSFs), and this technology can be utilized by the I2NSF architecture + to support the advanced security action. + Figure 3 shows an I2NSF framework with the support of SFC. As shown in the figure, SFC generally requires classifiers and 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 should pass through, according to pre-configured classification rules, and SFFs perform forwarding the given packet to the next service function (e.g., NSF) on the SFP of the packet by referring to their forwarding tables. In the I2NSF architecture with SFC, the Security Controller can take responsibilities of generating classification rules for classifiers @@ -407,57 +478,33 @@ classification rules of the SFPs, and then configures classifiers with the classification rules over NSF-Facing Interface so that relevant traffic packets can follow the SFPs. Also, based on the global view of NSF instances available in the system, the Security Controller constructs forwarding tables, which are required for SFFs to forward a given packet to the next NSF over the SFP, and configures SFFs with those forwarding tables over NSF-Facing Interface. To trigger an advanced security action in the I2NSF architecture, the - current NSF appends a metadata describing the security capability - required for the advanced action to the suspicious packet and sends + current NSF appends metadata describing the security capability + required for the advanced action to the suspicious packet to the + network service header (NSH) of the packet [RFC8300]. It then sends the packet to the classifier. Based on the metadata information, the classifier searches an SFP which includes an NSF with the required security capability, changes the SFP-related information (e.g., service path identifier and service index [RFC8300]) of the packet with the new SFP that has been found, and then forwards the packet to the SFF. When receiving the packet, the SFF checks the SFP-related information such as the service path identifier and service index contained in the packet and forwards the packet to the next NSF on the SFP of the packet, according to its forwarding table. -6. I2NSF Framework with SDN - - This section describes an I2NSF framework with SDN for I2NSF - applicability and use cases, such as firewall, deep packet - inspection, and DDoS-attack mitigation functions. SDN enables some - packet filtering rules to be enforced in network forwarding elements - (e.g., switch) by controlling their packet forwarding rules. By - taking advantage of this capability of SDN, it is possible to - optimize the process of security service enforcement in the I2NSF - system. - - Figure 4 shows an I2NSF framework [RFC8329] with SDN networks to - support network-based security services. In this system, the - enforcement of security policy rules is divided into the SDN - forwarding elements (e.g., switch running as either a hardware middle - box or a software virtual switch) and NSFs (e.g., firewall running in - a form of a virtual network function [ETSI-NFV]). Especially, SDN - forwarding elements enforce simple packet filtering rules that can be - translated into their packet forwarding rules, whereas NSFs enforce - NSF-related security rules requiring the security capabilities of the - NSFs. For this purpose, 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. - +------------+ | I2NSF User | +------------+ ^ | Consumer-Facing Interface v +-------------------+ Registration +-----------------------+ |Security Controller|<-------------------->|Developer's Mgmt System| +-------------------+ Interface +-----------------------+ ^ ^ @@ -479,20 +526,64 @@ | | SDN Southbound Interface | | v | | +--------+ +------------+ +--------+ +--------+ | | |Switch-1|-| Switch-2 |-|Switch-3|.......|Switch-m| | | | | |(Classifier)| | (SFF) | | | | | +--------+ +------------+ +--------+ +--------+ | +-------------------------------------------------------------------+ Figure 4: An I2NSF Framework with SDN Network +6. I2NSF Framework with SDN + + This section describes an I2NSF framework with SDN for I2NSF + applicability and use cases, such as firewall, deep packet + inspection, and DDoS-attack mitigation functions. SDN enables some + packet filtering rules to be enforced in network forwarding elements + (e.g., switch) by controlling their packet forwarding rules. By + taking advantage of this capability of SDN, it is possible to + optimize the process of security service enforcement in the I2NSF + system. For example, for efficient firewall services, simple packet + filtering can be performed by SDN forwarding elements (e.g., + switches), and complicated packet filtering based on packet payloads + can be performed by a firewall NSF. This optimized firewall using + both SDN forwarding elements and a firewall NSF is more efficient + than a firewall where SDN forwarding elements forward all the packets + to a firewall NSF for packet filtering. This is because packets to + be filtered out can be early dropped by SDN forwarding elements + without consuming further network bandwidth due to the forwarding of + the packets to the firewall NSF. + + Figure 4 shows an I2NSF framework [RFC8329] with SDN networks to + support network-based security services. In this system, the + enforcement of security policy rules is divided into the SDN + forwarding elements (e.g., switch running as either a hardware middle + box or a software virtual switch) and NSFs (e.g., firewall running in + a form of a virtual network function (VNF) [ETSI-NFV]). Note that + NSFs are created or removed by the NFV Management and Orchestration + (MANO) [ETSI-NFV-MANO], performing the life-cycle management of NSFs + as VNFs. Refer to Section 7 for the detailed discussion of the NSF + life-cycle management in the NFV MANO for I2NSF. SDN forwarding + elements enforce simple packet filtering rules that can be translated + into their packet forwarding rules, whereas NSFs enforce complicated + NSF-related security rules requiring the security capabilities of the + NSFs. Note that SDN packet forwarding rules are for packet + 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: 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- consuming packet inspection rule for analyzing whether an attached file being transmitted over a flow of packets contains malware. Rule A can be translated into packet forwarding rules of SDN forwarding elements and thus be enforced by these elements. In contrast, rule B cannot be enforced by forwarding elements, but it has to be enforced by NSFs with anti-malware capability. Specifically, a flow of packets is forwarded to and reassembled by an NSF to reconstruct the @@ -507,24 +598,27 @@ rules requires security capabilities that can be provided by SDN forwarding elements, then the Security Controller instructs the SDN Controller via NSF-Facing Interface so that SDN forwarding elements can enforce those security policy rules with flow tables under the supervision of the SDN Controller. Or if some rules require security capabilities that cannot be provided by SDN forwarding elements but by NSFs, then the Security Controller instructs relevant NSFs to enforce those rules. The distinction between software-based SDN forwarding elements and - NSFs, which can both run as virtual network functions, may be - necessary for some management purposes in this system. For this, we - can take advantage of the NFV MANO where there is a subsystem that - maintains the descriptions of the capabilities each VNF can offer + NSFs, which can both run as virtual network functions (VNFs), may be + necessary for some management purposes in this system. Note that an + SDN forwarding element (i.e., switch) is a specific type of VNF + rather than an NSF because an NSF is for security services rather + than for packet forwarding. For this distinction, we can take + advantage of the NFV MANO where there is a subsystem that maintains + the descriptions of the capabilities each VNF can offer [ETSI-NFV-MANO]. This subsystem can determine whether a given software element (VNF instance) is an NSF or a virtualized SDN switch. For example, if a VNF instance has anti-malware capability according to the description of the VNF, it could be considered as an NSF. A VNF onboarding system [VNF-ONBOARDING] can be used as such a subsystem that maintains the descriptions of each VNF to tell whether a VNF instance is for an NSF or for a virtualized SDN switch. 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 @@ -533,266 +627,80 @@ Security Controller. This interface is used to update security service function chaining information for traffic flows. For 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 Security Controller to update the SFP for the traffic flow (needing another security service as an NSF) via NSF-Facing Interface. This update lets Security Controller ask Classifier (denoted as Switch-2) to update the mapping between the traffic flow and SFP in Classifier via NSF-Facing Interface. - 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] + The following subsections introduce three use cases from [RFC8192] + for cloud-based security services: (i) firewall system, (ii) deep + packet inspection system, and (iii) attack mitigation system. 6.1. Firewall: Centralized Firewall System A centralized network firewall can manage each network resource and apply common rules to individual network elements (e.g., switch). The centralized network firewall controls each forwarding element, and 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 SDN - Controllers. - - 2. The SDN 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 SDN - Controller. - - 5. The SDN 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. + A time-based firewall can be enforced with packet filtering rules and + a time span (e.g., work hours). With this time-based firewall, a + time-based security policy can be enforced, as explained in + Section 4. For example, employees at a company are allowed to access + social networking service websites during lunch time or after work + hours. 6.2. 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, according to the configuration of a VoIP/VoLTE security service called VoIP Intrusion Prevention System (IPS). This centralized 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. The centralized VoIP/VoLTE security system can cooperate with a network firewall to realize VoIP/VoLTE security service. Specifically, a network firewall performs the basic security check 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 SDN Controller, - and the SDN 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. In order for this triggering of VoIP - IPS to be served, the suspicious packet is sent to the Service - Function Forwarder (SFF) that is usually a switch in an SDN - network, as shown in Figure 4. 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 SDN Controller to block that packet and the subsequent - packets that have the same call-id. - - 6. The SDN Controller installs new rules (e.g., drop packets) into - underlying switches. - - 7. The malicious 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 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 - 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 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 - 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. - 6.3. Attack Mitigation: Centralized DDoS-attack Mitigation System A centralized DDoS-attack mitigation can manage each network resource and configure rules to each switch for DDoS-attack mitigation (called DDoS-attack Mitigator) on a common server. The centralized DDoS- attack mitigation system defends servers against DDoS attacks outside the private network, that is, from public networks. Servers are categorized into stateless servers (e.g., DNS servers) and stateful servers (e.g., web servers). For DDoS-attack mitigation, the forwarding of traffic flows in switches can be dynamically configured such that malicious traffic flows are handled by the paths separated from normal traffic flows in order to minimize - the impact of those malicious traffic on the the servers. This flow - path separation can be done by a flow forwarding path management - scheme based on [AVANT-GUARD]. This management should consider the - load balance among the switches for the defense against DDoS attacks. - - The procedure of DDoS-attack mitigation in this system is as follows: - - 1. A Switch periodically reports an inter-arrival pattern of a - flow's packets to one of the SDN Controllers. - - 2. The SDN 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 the - SDN Controller. - - 5. The SDN 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, for dynamic network resource management, a flow - forwarding path management scheme can handle the load balancing of - network switches [AVANT-GUARD]. With this management scheme, 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. + the impact of those malicious traffic on the servers. This flow path + separation can be done by a flow forwarding path management scheme + based on [AVANT-GUARD]. This management should consider the load + balance among the switches for the defense against DDoS attacks. - So far this section 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 + So far this section has described 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]. +--------------------+ +-------------------------------------------+ | ---------------- | | I2NSF User (OSS/BSS) | | | NFV | | +------+------------------------------------+ | | Orchestrator +-+ | | Consumer-Facing Interface | -----+---------- | | +------|------------------------------------+ | | | | @@ -847,29 +755,32 @@ on security requirements. In order to take advantages of the NFV technology, the I2NSF framework can be implemented on top of an NFV infrastructure as show in Figure 5. Figure 5 shows an I2NSF framework implementation based on the NFV reference architecture that the European Telecommunications Standards Institute (ETSI) defines [ETSI-NFV]. The NSFs are deployed as virtual network functions (VNFs) in Figure 5. The Developer's Management System (DMS) in the I2NSF framework is responsible for registering capability information of NSFs into the Security - Controller. Those NSFs are created or removed by a virtual network - functions manager (VNFM) in the NFV architecture that performs the - life-cycle management of VNFs. The Security Controller controls and - monitors the configurations (e.g., function parameters and security - policy rules) of VNFs. Both the DMS and Security Controller can be - implemented as the Element Managements (EMs) in the NFV architecture. - Finally, the I2NSF User can be implemented as OSS/BSS (Operational - Support Systems/Business Support Systems) in the NFV architecture - that provides interfaces for users in the NFV system. + Controller. However, those NSFs are created or removed by a virtual + network functions manager (VNFM) in the NFV MANO that performs the + life-cycle management of VNFs. Note that the life-cycle management + of VNFs are out of scope for I2NSF. The Security Controller controls + and monitors the configurations (e.g., function parameters and + security policy rules) of VNFs via NSF-Facing Interface along with + NSF monitoring capability [nsf-facing-inf-dm][nsf-monitoring-dm]. + Both the DMS and Security Controller can be implemented as the + Element Managements (EMs) in the NFV architecture. Finally, the + I2NSF User can be implemented as OSS/BSS (Operational Support + Systems/Business Support Systems) in the NFV architecture that + provides interfaces for users in the NFV system. The operation procedure in the I2NSF framework based on the NFV architecture is as follows: 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 a set of security capabilities. The DMS initially registers a mapping table of the ID of each VM image and the set of capabilities that can be provided by an NSF instance created from the VM image into the Security Controller. @@ -895,22 +806,20 @@ 6. After being notified of the created NSF instance, the Security Controller delivers low-level security policy rules to the NSF instance for policy enforcement. We can conclude that the I2NSF framework can be implemented based on the NFV architecture framework. Note that the registration of the capabilities of NSFs is performed through the Registration Interface and the lifecycle management for NSFs (VNFs) is performed through the Ve-Vnfm interface between the DMS and VNFM, as shown in Figure 5. - More details about the I2NSF framework based on the NFV reference - architecture are described in [i2nsf-nfv-architecture]. 8. Security Considerations The same security considerations for the I2NSF framework [RFC8329] are applicable to this document. This document shares all the security issues of SDN that are specified in the "Security Considerations" section of [ITU-T.Y.3300]. 9. Acknowledgments @@ -961,26 +869,20 @@ Available: https://www.itu.int/rec/T-REC-Y.3300-201406-I, June 2014. [NFV-Terminology] "Network Functions Virtualisation (NFV); Terminology for Main Concepts in NFV", Available: https://www.etsi.org/deliver/etsi_gs/ NFV/001_099/003/01.02.01_60/gs_nfv003v010201p.pdf, December 2014. - [ONF-OpenFlow] - "OpenFlow Switch Specification (Version 1.4.0)", - Available: https://www.opennetworking.org/wp- - content/uploads/2014/10/openflow-spec-v1.4.0.pdf, October - 2013. - [ONF-SDN-Architecture] "SDN Architecture (Issue 1.1)", Available: https://www.opennetworking.org/wp- content/uploads/2014/10/TR- 521_SDN_Architecture_issue_1.1.pdf, June 2016. [RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, October 2010. @@ -1023,111 +925,97 @@ ietf-i2nsf-consumer-facing-interface-dm-03 (work in progress), March 2019. [ETSI-NFV-MANO] "Network Functions Virtualisation (NFV); Management and Orchestration", Available: https://www.etsi.org/deliver/etsi_gs/nfv- man/001_099/001/01.01.01_60/gs_nfv-man001v010101p.pdf, December 2014. - [i2nsf-nfv-architecture] - Yang, H., Kim, Y., Jeong, J., and J. Kim, "I2NSF on the - NFV Reference Architecture", draft-yang-i2nsf-nfv- - architecture-04 (work in progress), November 2018. - - [i2nsf-nsf-cap-im] - Xia, L., Strassner, J., Basile, C., and D. Lopez, - "Information Model of NSFs Capabilities", draft-ietf- - i2nsf-capability-04 (work in progress), October 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-07 (work in progress), January 2019. - [ITU-T.X.1252] - "Baseline Identity Management Terms and Definitions", - April 2010. - [ITU-T.X.800] "Security Architecture for Open Systems Interconnection for CCITT Applications", March 1991. [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-dm-03 (work in progress), March 2019. [nsf-monitoring-dm] Jeong, J., Chung, C., Hares, S., Xia, L., and H. Birkholz, "A YANG Data Model for Monitoring I2NSF Network Security Functions", draft-ietf-i2nsf-nsf-monitoring-data-model-00 (work in progress), March 2019. - [nsf-triggered-steering] - Hyun, S., Jeong, J., Park, J., and S. Hares, "Service - Function Chaining-Enabled I2NSF Architecture", draft-hyun- - i2nsf-nsf-triggered-steering-06 (work in progress), July - 2018. - [opsawg-firewalls] Baker, F. and P. Hoffman, "On Firewalls in Internet Security", draft-ietf-opsawg-firewalls-01 (work in progress), October 2012. [policy-translation] Yang, J., Jeong, J., and J. Kim, "Security Policy Translation in Interface to Network Security Functions", draft-yang-i2nsf-security-policy-translation-03 (work in progress), March 2019. [registration-inf-dm] Hyun, S., Jeong, J., Roh, T., Wi, S., and J. Park, "I2NSF Registration Interface YANG Data Model", draft-ietf-i2nsf- registration-interface-dm-02 (work in progress), March 2019. - [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session - Description Protocol", RFC 4566, July 2006. - [VNF-ONBOARDING] "VNF Onboarding", Available: https://wiki.opnfv.org/display/mano/VNF+Onboarding, November 2016. -Appendix A. Changes from draft-ietf-i2nsf-applicability-08 +Appendix A. Changes from draft-ietf-i2nsf-applicability-09 The following changes have been made from draft-ietf-i2nsf- - applicability-08: + applicability-09: - o This version has reflected the additional comments from Eric - Rescorla who is a Security Area Director as follows. + o This version has reflected the questions and comments from Roman + Danyliw who is a Security Area Director as follows. - o In Section 3, for a Developer's Management System, the problem of - an inside attacker is addressed, and a possible solution for the - inside attacks is suggested through I2NSF NSF monitoring - functionality. Also, some restrictions on the role of the DMS are - required to deal with the inside attacks. + o In Section 1, the description of I2NSF components and interfaces + is clarified with typo correction. - o In Section 4, an XML code for the time-dependent web access - control is explained as an example. + o In Section 2, unnecessary references are deleted, and the + definition of a term "NSF" is clarified with the I2NSF terminology + draft [i2nsf-terminology]. + + o In Section 3, inside attacks at DMS or I2NSF User are described + clearly along with feasible counterattacks against those inside + attacks. Also, the usage of RESTCONF and NETCONF with YANG data + model language is clarified for three I2NSF interfaces such as the + Consumer-Facing Interface, NSF-Facing Interface, and Registration + Interface. + + o In Section 4, a real XML code for the time-dependent web access + control is added for the Consumer-Facing Interface as an example. + + o In Section 5, the network service header (NSH) as a reference is + added for the metadata format for I2NSF traffic steering based on + SFC. o In Section 6, the definitions of an SDN forwarding element and an - NSF are clarified such that an SDN forwarding element is a switch - running as either a hardware middle box or a software virtual - switch, and an NSF is a virtual network function for a security - service. It also discusses about how to determine whether a given - software element in virtualized environments is an NSF or a - virtualized switch. + NSF are clarified. Also, the optimization of an SDN-and-NFV-based + firewall is explained clearly in terms of delay and network + bandwidth saving. Authors' Addresses Jaehoon Paul Jeong Department of Software Sungkyunkwan University 2066 Seobu-Ro, Jangan-Gu Suwon, Gyeonggi-Do 16419 Republic of Korea