| I2NSF Working Group | J. Jeong |
| Internet-Draft | Sungkyunkwan University |
| Intended status: Informational | S. Hyun |
| Expires: April 25, 2019 | Chosun University |
| T. Ahn | |
| Korea Telecom | |
| S. Hares | |
| Huawei | |
| D. Lopez | |
| Telefonica I+D | |
| October 22, 2018 |
Applicability of Interfaces to Network Security Functions to Network-Based Security Services
draft-ietf-i2nsf-applicability-06
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.
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Interface to Network Security Functions (I2NSF) defines a framework and interfaces for interacting with Network Security Functions (NSFs). The I2NSF framework allows heterogeneous NSFs developed by different security solution vendors to be used in the 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 Client (also called I2NSF User) that the user is employing, so that the user can request security services through the Security Controller.
This document illustrates the applicability of the I2NSF framework with four different scenarios: (i) the enforcement of time-dependent web access control; (ii) the application of I2NSF to a Service Function Chaining (SFC) environment [RFC7665]; (iii) the integration of the I2NSF framework with Software-Defined Networking (SDN) [RFC7149] to provide different security functionality such as firewalls [opsawg-firewalls], Deep Packet Inspection (DPI), and Distributed Denial of Service (DDoS) attack mitigation; (iv) the use of NFV as 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.
This document uses the terminology described in [RFC7149], [ITU-T.Y.3300], [ONF-OpenFlow], [ONF-SDN-Architecture], [ITU-T.X.1252], [ITU-T.X.800], [RFC8329], [i2nsf-terminology], [consumer-facing-inf-im], [consumer-facing-inf-dm], [i2nsf-nsf-cap-im], [nsf-facing-inf-dm], [registration-inf-dm], and [nsf-triggered-steering]. In addition, the following terms are defined below:
+------------+
| I2NSF User |
+------------+
^
| Consumer-Facing Interface
v
+-------------------+ Registration +-----------------------+
|Security Controller|<-------------------->|Developer's Mgmt System|
+-------------------+ Interface +-----------------------+
^
| NSF-Facing Interface
v
+----------------+ +---------------+ +-----------------------+
| NSF-1 |-| NSF-2 |...| NSF-n |
| (Firewall) | | (Web Filter) | |(DDoS-Attack Mitigator)|
+----------------+ +---------------+ +-----------------------+
Figure 1: I2NSF Framework
This section summarizes the I2NSF framework as defined in [RFC8329]. As shown in Figure 1, an I2NSF User can use security functions by delivering high-level security policies, which specify security requirements that the I2NSF user wants to enforce, to the Security Controller via the Consumer-Facing Interface [consumer-facing-inf-im][consumer-facing-inf-dm].
The Security Controller receives and analyzes the high-level security policies from an I2NSF User, and identifies what types of security capabilities are required to meet these high-level security policies. The Security Controller then identifies NSFs that have the required security capabilities, and generates low-level security policies for each of the NSFs so that the high-level security policies are eventually enforced by those NSFs [policy-translation]. Finally, the Security Controller sends the generated low-level security policies to the NSFs [i2nsf-nsf-cap-im][nsf-facing-inf-dm].
The Security Controller requests NSFs to perform low-level security services via the NSF-Facing Interface. The 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.
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 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 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.
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].
The following sections describe different security service scenarios illustrating the applicability of the I2NSF framework.
This service scenario assumes that an enterprise network administrator wants to control the staff members' access to a particular Interner service (e.g., Example.com) during business hours. The following is an example high-level security policy rule that the administrator requests: Block the staff members' access to Example.com from 9 AM to 6 PM. The administrator sends this high-level security policy to the Security Controller, then 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 Registation 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.
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 checks 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.
The following describes how the time-dependent web access control service is enforced by the NSFs of firewall and web filter.
+------------+
| I2NSF User |
+------------+
^
| Consumer-Facing Interface
v
+-------------------+ Registration +-----------------------+
|Security Controller|<-------------------->|Developer's Mgmt System|
+-------------------+ Interface +-----------------------+
^ ^
| | NSF-Facing Interface
| |-------------------------
| |
| NSF-Facing Interface |
+-----v-----------+ +------v-------+
| +-----------+ | ------>| NSF-1 |
| |Classifier | | | | (Firewall) |
| +-----------+ | | +--------------+
| +-----+ |<-----| +--------------+
| | SFF | | |----->| NSF-2 |
| +-----+ | | | (DPI) |
+-----------------+ | +--------------+
| .
| .
| .
| +-----------------------+
------>| NSF-n |
|(DDoS-Attack Mitigator)|
+-----------------------+
Figure 2: An 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 2 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 and forwarding tables for SFFs. By analyzing high-level security policies from I2NSF users, the Security Controller can construct SFPs that are required to meet the high-level security policies, generates 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 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.
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.
+------------+
| I2NSF User |
+------------+
^
| Consumer-Facing Interface
v
+-------------------+ Registration +-----------------------+
|Security Controller|<-------------------->|Developer's Mgmt System|
+-------------------+ Interface +-----------------------+
^ ^
| | NSF-Facing Interface
| v
| +----------------+ +---------------+ +-----------------------+
| | NSF-1 |-| NSF-2 |...| NSF-n |
| | (Firewall) | | (DPI) | |(DDoS-Attack Mitigator)|
| +----------------+ +---------------+ +-----------------------+
|
|
| SDN Network
+--|----------------------------------------------------------------+
| V NSF-Facing Interface |
| +----------------+ |
| | SDN Controller | |
| +----------------+ |
| ^ |
| | SDN Southbound Interface |
| v |
| +--------+ +------------+ +--------+ +--------+ |
| |Switch-1|-| Switch-2 |-|Switch-3|.......|Switch-m| |
| | | |(Classifier)| | (SFF) | | | |
| +--------+ +------------+ +--------+ +--------+ |
+-------------------------------------------------------------------+
Figure 3: An I2NSF Framework with SDN Network
Figure 3 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) and NSFs. 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.
As an example, let us consider two different types of security rules: Rule A is a simple packet fltering rule that checks only the IP address and port number 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 attached file stored in the flow of packets. The NSF then analyzes the file to check the existence of malware. If the file contains malware, the NSF drops the packets.
In an I2NSF framework with SDN, the Security Controller can analyze given security policy rules and automatically determine which of the given security policy rules should be enforced by SDN forwarding elements and which should be enforced by NSFs. If some of the given 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.
For the support of SFC in the I2NSF framework with SDN, as shown in Figure 3, network forwarding elements (e.g., switch) can play the role of either SFC Classifier or SFF, which are explained in Section 5. Classifier and SFF have an NSF-Facing Interface with 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 3, 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]
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:
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:
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 basic security checks of an unknown flow's packet observed by a switch. If the network firewall detects that the packet is an unknown VoIP call flow's packet that exhibits some suspicious patterns, then it triggers the VoIP/VoLTE security system for more specialized security analysis of the suspicious VoIP call packet.
The procedure of VoIP/VoLTE security operations in this system is as follows:
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:
A centralized DDoS-attack mitigation can manage each network resource and manipulate rules to each switch through a common server for DDoS-attack mitigation (called DDoS-attack Mitigator). 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, traffic flows in switches are dynamically configured by traffic flow forwarding path management according to the category of servers [AVANT-GUARD]. Such a managenent should consider the load balance among the switches for the defense against DDoS attacks.
The procedure of DDoS-attack mitigation operations in this system is as follows:
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:
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 [registration-inf-dm] can be used as Consumer-Facing Interface, NSF-Facing Interface, and Registration Interface, respectively, along with RESTCONF [RFC8040] and NETCONF [RFC6241].
This section discusses the implementation of the I2NSF framework using Network Functions Virtualization (NFV).
+--------------------+
+-------------------------------------------+ | ---------------- |
| I2NSF User (OSS/BSS) | | | NFV | |
+------+------------------------------------+ | | Orchestrator +-+ |
| Consumer-Facing Interface | -----+---------- | |
+------|------------------------------------+ | | | |
| -----+---------- (a) ----------------- | | ----+----- | |
| | Security +-------+ Developer's | | | | | | |
| |Controller(EM)| |Mgmt System(EM)| +-(b)-+ VNFM(s)| | |
| -----+---------- ----------------- | | | | | |
| | NSF-Facing Interface | | ----+----- | |
| ----+----- ----+----- ----+----- | | | | |
| |NSF(VNF)| |NSF(VNF)| |NSF(VNF)| | | | | |
| ----+----- ----+----- ----+----- | | | | |
| | | | | | | | |
+------|-------------|-------------|--------+ | | | |
| | | | | | |
+------+-------------+-------------+--------+ | | | |
| NFV Infrastructure (NFVI) | | | | |
| ----------- ----------- ----------- | | | | |
| | Virtual | | Virtual | | Virtual | | | | | |
| | Compute | | Storage | | Network | | | | | |
| ----------- ----------- ----------- | | ----+----- | |
| +---------------------------------------+ | | | | | |
| | Virtualization Layer | +-----+ VIM(s) +------+ |
| +---------------------------------------+ | | | | |
| +---------------------------------------+ | | ---------- |
| | ----------- ----------- ----------- | | | |
| | | Compute | | Storage | | Network | | | | |
| | | Hardware| | Hardware| | Hardware| | | | |
| | ----------- ----------- ----------- | | | |
| | Hardware Resources | | | NFV Management |
| +---------------------------------------+ | | and Orchestration |
| | | (MANO) |
+-------------------------------------------+ +--------------------+
(a) = Registration Interface
(b) = Ve-Vnfm Interface
Figure 4: I2NSF Framework Implementation with respect to the NFV Reference Architectural Framework
NFV is a promising technology for improving the elasticity and efficiency of network resource utilization. In NFV environments, NSFs can be deployed in the forms of software-based virtual instances rather than physical appliances. Virtualizing NSFs makes it possible to rapidly and flexibly respond to the amount of service requests by dynamically increasing or decreasing the number of NSF instances. Moreover, NFV technology facilitates flexibly including or excluding NSFs from multiple security solution vendors according to the changes 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 4.
Figure 4 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 4. 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.
The operation procedure in the I2NSF framework based on the NFV architecture is as follows: Figure 4. More details about the I2NSF framework based on the NFV reference architecture are described in [i2nsf-nfv-architecture].
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
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].
This work was supported by Institute for Information & communications Technology Promotion (IITP) grant funded by the Korea government (MSIP) (No.R-20160222-002755, Cloud based Security Intelligence Technology Development for the Customized Security Service Provisioning).
I2NSF is a group effort. I2NSF has had a number of contributing authors. The following are considered co-authors:
The following change has been made from draft-ietf-i2nsf-applicability-05: