None. G. Jones, Editor Internet-Draft The MITRE Corporation Expires: April 24, 2004 October 25, 2003 Operational Security Requirements for IP Network Infrastructure: Best-Current-Practices draft-jones-opsec-02 Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. 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." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 24, 2004. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This document defines a list of operational security requirements for the infrastructure of large IP networks (routers and switches) which are considered to be best current practice (BCP). A framework is defined for specifying "profiles", which are collections of requirements applicable to certain classes of devices (all, core-only, edge-only...). The goal is to provide consumers of network equipment a clear, concise way of communicating their security requirements to vendors of such equipment. The requirements in this document are considered to be best current practice (BCP). Comments to: "opsec-comment@ops.ietf.org". Jones, Editor Expires April 24, 2004 [Page 1] Internet-Draft Operational Security Requirements October 2003 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 5 1.1 Goals . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.2 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.3 Definition of a Secure Network . . . . . . . . . . . . . . 5 1.4 Intended Audience . . . . . . . . . . . . . . . . . . . . 6 1.5 Format . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.6 Intended Use . . . . . . . . . . . . . . . . . . . . . . . 7 1.7 Definitions . . . . . . . . . . . . . . . . . . . . . . . 7 2. Functional Requirements . . . . . . . . . . . . . . . . . 8 2.1 Device Management Requirements . . . . . . . . . . . . . . 8 2.1.1 Support Secure Management Channels . . . . . . . . . . . . 8 2.2 In-Band Management Requirements . . . . . . . . . . . . . 8 2.2.1 Use Encryption Algorithms Subject To Open Review . . . . . 9 2.2.2 Use Strong Encryption . . . . . . . . . . . . . . . . . . 9 2.3 Out-of-Band (OoB) Management Requirements . . . . . . . . 10 2.3.1 Support a Non-IP 'Console' interface . . . . . . . . . . . 10 2.3.2 Support A Simple Default Communication Profile On The 'Console' . . . . . . . . . . . . . . . . . . . . . . . . 10 2.3.3 Support Separate Management Plane IP Interfaces . . . . . 11 2.3.4 No Forwarding Between Management Plane And Other Interfaces . . . . . . . . . . . . . . . . . . . . . . . . 12 2.3.5 Provide Separate Resources For The Management Plane . . . 12 2.4 Configuration and Management Interface Requirements . . . 12 2.4.1 CLI Provides Access to All Configuration and Management Functions . . . . . . . . . . . . . . . . . . . 13 2.4.2 CLI Uses Existing Authentication Mechanisms . . . . . . . 13 2.4.3 CLI Supports Scripting of Configuration . . . . . . . . . 13 2.4.4 CLI Supports Management Over 'Slow' Links . . . . . . . . 14 2.4.5 Support Software Installation . . . . . . . . . . . . . . 14 2.4.6 Support Remote Configuration Backup . . . . . . . . . . . 15 2.4.7 Support Remote Configuration Restore . . . . . . . . . . . 16 2.4.8 Support Human-Readable Configuration File . . . . . . . . 16 2.5 IP Stack Requirements . . . . . . . . . . . . . . . . . . 16 2.5.1 Ability to Identify All Listening Services . . . . . . . . 17 2.5.2 Ability to Disable Any and All Services . . . . . . . . . 17 2.5.3 Listening Services Should Be Off By Default . . . . . . . 17 2.5.4 Ability to Control Service Bindings for Listening Services . . . . . . . . . . . . . . . . . . . . . . . . . 18 2.5.5 Ability to Control Service Source Address . . . . . . . . 18 2.5.6 Support Automatic Anti-spoofing for Single-Homed Networks . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.5.7 Directed Broadcasts Disabled by Default . . . . . . . . . 20 2.6 Rate Limiting Requirements . . . . . . . . . . . . . . . . 20 2.6.1 Support Rate Limiting . . . . . . . . . . . . . . . . . . 20 2.6.2 Support Rate Limiting Based on State . . . . . . . . . . . 21 2.7 Basic Filtering Capabilities . . . . . . . . . . . . . . . 21 Jones, Editor Expires April 24, 2004 [Page 2] Internet-Draft Operational Security Requirements October 2003 2.7.1 Ability to Filter Traffic . . . . . . . . . . . . . . . . 21 2.7.2 Ability to Filter Traffic TO the Device . . . . . . . . . 22 2.7.3 Ability to Filter Traffic THROUGH the Device . . . . . . . 22 2.7.4 Ability to Filter Without Performance Degradation . . . . 22 2.7.5 Ability to Filter Updates . . . . . . . . . . . . . . . . 23 2.7.6 Ability to Specify Filter Actions . . . . . . . . . . . . 24 2.7.7 Ability to Log Filter Actions . . . . . . . . . . . . . . 24 2.8 Packet Filtering Criteria . . . . . . . . . . . . . . . . 25 2.8.1 Ability to Filter on Protocols . . . . . . . . . . . . . . 25 2.8.2 Ability to Filter on Addresses . . . . . . . . . . . . . . 25 2.8.3 Ability to Filter on Any Protocol Header Fields . . . . . 25 2.8.4 Ability to Filter Inbound and Outbound . . . . . . . . . . 26 2.9 Packet Filtering Counter Requirements . . . . . . . . . . 26 2.9.1 Ability to Accurately Count Filter Hits . . . . . . . . . 26 2.9.2 Ability to Display Filter Counters . . . . . . . . . . . . 27 2.9.3 Ability to Display Filter Counters per Rule . . . . . . . 27 2.9.4 Ability to Display Filter Counters per Filter Application . . . . . . . . . . . . . . . . . . . . . . . 28 2.9.5 Ability to Reset Filter Counters . . . . . . . . . . . . . 28 2.9.6 Filter Counters Must Be Accurate . . . . . . . . . . . . . 28 2.10 Other Packet Filtering Requirements . . . . . . . . . . . 29 2.10.1 Filter, Counters, and Filter Log Must Have Minimal Performance Impact . . . . . . . . . . . . . . . . . . . . 29 2.10.2 Ability to Specify Filter Log Granularity . . . . . . . . 30 2.11 Event Logging Requirements . . . . . . . . . . . . . . . . 30 2.11.1 Logging Facility Conforms to Open Standards . . . . . . . 30 2.11.2 Ability to Log to Remote Server . . . . . . . . . . . . . 31 2.11.3 Ability to Log Locally . . . . . . . . . . . . . . . . . . 31 2.11.4 Ability to Maintain Accurate System Time . . . . . . . . . 31 2.11.5 Logs Must Be Timestamped . . . . . . . . . . . . . . . . . 32 2.11.6 Logs Contain Untranslated Addresses . . . . . . . . . . . 32 2.12 Authentication, Authorization, and Accounting (AAA) Requirements . . . . . . . . . . . . . . . . . . . . . . . 33 2.12.1 Authenticate All User Access . . . . . . . . . . . . . . . 33 2.12.2 Support Authentication of Individual Users . . . . . . . . 33 2.12.3 Support Simultaneous Connections . . . . . . . . . . . . . 34 2.12.4 Ability to Disable All Local Accounts . . . . . . . . . . 34 2.12.5 Support Centralized User Authentication Methods . . . . . 35 2.12.6 Support Local User Authentication Method . . . . . . . . . 35 2.12.7 Support Configuration of Order of Authentication Methods . . . . . . . . . . . . . . . . . . . . . . . . . 36 2.12.8 No Unencrypted Transmission of Reusable Plain-text Passwords . . . . . . . . . . . . . . . . . . . . . . . . 36 2.12.9 No Default Passwords . . . . . . . . . . . . . . . . . . . 37 2.12.10 Passwords Must Be Explicitly Configured Prior To Use . . . 37 2.12.11 Ability to Define Privilege Levels . . . . . . . . . . . . 38 2.12.12 Ability to Assign Privilege Levels to Users . . . . . . . 38 2.12.13 Default Privilege Level Must Be Read Only . . . . . . . . 39 Jones, Editor Expires April 24, 2004 [Page 3] Internet-Draft Operational Security Requirements October 2003 2.12.14 Change in Privilege Levels Requires Re-Authentication . . 39 2.12.15 Support Recovery Of Privileged Access . . . . . . . . . . 39 2.12.16 Accounting Records . . . . . . . . . . . . . . . . . . . . 40 2.13 Layer 2 Devices Must Meet Higher Layer Requirements . . . 41 3. Documentation Requirements . . . . . . . . . . . . . . . . 42 3.1 Document Listening Services . . . . . . . . . . . . . . . 42 4. Assurance Requirements . . . . . . . . . . . . . . . . . . 43 4.1 Comply With Relevant IETF RFCs on All Protocols Implemented . . . . . . . . . . . . . . . . . . . . . . . 43 4.2 Identify Origin of IP Stack . . . . . . . . . . . . . . . 44 4.3 Identify Origin of Operating System . . . . . . . . . . . 44 5. Security Considerations . . . . . . . . . . . . . . . . . 46 References . . . . . . . . . . . . . . . . . . . . . . . . 47 Author's Address . . . . . . . . . . . . . . . . . . . . . 48 A. Requirement Profiles . . . . . . . . . . . . . . . . . . . 49 A.1 Minimum Requirements Profile . . . . . . . . . . . . . . . 49 A.1.1 Functional Requirements . . . . . . . . . . . . . . . . . 49 A.1.2 Documentation Requirements . . . . . . . . . . . . . . . . 52 A.1.3 Assurance Requirements . . . . . . . . . . . . . . . . . . 53 A.2 Layer 3 Network Core Profile . . . . . . . . . . . . . . . 53 A.2.1 Functional Requirements . . . . . . . . . . . . . . . . . 53 A.3 Layer 3 Network Edge Profile . . . . . . . . . . . . . . . 53 A.3.1 Functional Requirements . . . . . . . . . . . . . . . . . 53 B. Acknowledgments . . . . . . . . . . . . . . . . . . . . . 55 Intellectual Property and Copyright Statements . . . . . . 56 Jones, Editor Expires April 24, 2004 [Page 4] Internet-Draft Operational Security Requirements October 2003 1. Introduction 1.1 Goals This document defines a list of operational security requirements for the infrastructure of large IP networks (routers and switches) which are considered to be best current practice (BCP). The goal is to provide consumers of IP network infrastructure a clear, concise way of communicating their security requirements to equipment vendors. 1.2 Scope The primary scope of these requirements is intended to cover the infrastructure of large IP networks (e.g. routers and switches). Certain groups (or "profiles", see below) apply only in specific situations (e.g. all, edge-only, core-only). The requirements listed in the minimum profile are intended to apply to all managed infrastructure devices. General purpose hosts (including infrastructure hosts such as name/ time/log/AA servers, etc.), unmanaged, or customer managed devices (e.g. firewalls, Intrusion Detection System, dedicated VPN devices, etc.) are explicitly out of scope. This means that while the requirements in the minimum profile (and others) may apply, additional requirements will not be added to account for their unique needs. Confidentiality and integrity of customer data are outside the scope. While, the examples given are written with IPv4 in mind, most of the requirements are general enough to apply to IPv6. 1.3 Definition of a Secure Network For the purposes of this document, a secure network is one in which: o the network keeps passing legitimate customer traffic (availability) o traffic goes where its supposed to go (availability,confidentiality) o the network elements remain manageable (availability) o only authorized users can manage network elements (authorization) o there is record of all security related events (accountability) Jones, Editor Expires April 24, 2004 [Page 5] Internet-Draft Operational Security Requirements October 2003 o the network operator has the necessary tools to detect and respond to illegitimate traffic The following assumptions are made: o Devices are physically secure. o The management infrastructure (AAA/DNS/log server, SNMP management stations, etc.) is secure. 1.4 Intended Audience There are two intended audiences: the end user (consumer) who selects, purchases, and operates IP network equipment, and the vendors who create them. 1.5 Format The individual requirements are listed in one of the three sections listed below. o Section 2 lists functional requirements. o Section 3 lists documentation requirements. o Section 4 lists assurance requirements. Within these areas, requirements are grouped in major functional areas (e.g., logging, authentication, filtering, etc.) Each requirement has the following subsections: o The Requirement (What) o The Justification (Why) o Examples (How) o Warnings (if applicable) The requirement describes a policy to be supported by the device. The justification tells why and in what context the requirement is important. The examples section is intended to give examples of implementations that may meet the requirement. Examples cite technology and standards current at the time of this writing. It is expected that the choice of implementations to meet the requirements will change over time. The warnings list operational concerns, Jones, Editor Expires April 24, 2004 [Page 6] Internet-Draft Operational Security Requirements October 2003 deviation from standards, caveats, etc. Security requirements will vary across different device types and different organizations, depending on policy and other factors. A desired feature in one environment may be a requirement in another. Classifications must be made according to local need. In order to assist in classification, the Appendix Appendix A defines several requirement "profiles" for different types of devices. Profiles are simply collections of requirements. They provide a concise list of the requirements that apply to certain classes of devices. The profiles in this document should be reviewed to determine if they are appropriate the local environment. 1.6 Intended Use It is anticipated that this document will be used in the following manners: Security Capability Checklist The requirements in this document may be used as a checklist when evaluating networked products. Composing Profiles Different subsets of these requirements may be compiled to describe the needs of different devices, organizations, and operating environments. Communicating Requirements This document may be referenced, along with profiles, to clearly communicate security requirements. Basis For Testing and Certification This document may form the basis for testing and certification of security features of networked products. 1.7 Definitions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Unless otherwise indicated, "IP" refers to IPv4 Jones, Editor Expires April 24, 2004 [Page 7] Internet-Draft Operational Security Requirements October 2003 2. Functional Requirements The requirements in this section are intended to list testable, functional requirements that are needed to operate devices securely. 2.1 Device Management Requirements 2.1.1 Support Secure Management Channels Requirement. The device MUST provide secure end-to-end channels for all network traffic and protocols used to support management functions. This MUST include at least protocols used for configuration, monitoring, configuration backup, logging, time synchronization, authentication, and routing. This requirement MAY be satisfied using either In-Band or Out-of-Band management. See Section 2.2 and Section 2.3. Justification. Secure channels ensure confidentiality and integrity of management traffic. Examples. Different mechanisms may be used with different protocols to satisfy this requirement. Secure management can be achieved by the use of in-band protocols that support encryption, by using insecure protocols over top of secure transports such as TLS or IPsec or by the use of out-of-band management. For example Secure protocols: SSH, SFTP, SNMPv3, BGP, NTP, Kerberos. Insecure protocols tunneled: telnet, TFTP, SNMPv1 syslog, over TLS or IPsec Warnings. None. 2.2 In-Band Management Requirements This section lists security requirements for devices that are managed In-band. "In-band management" is defined as any management done over the same channels and interfaces used for user/customer data. Examples would include using SSH for management via customer or Internet facing network interfaces. In-band management has the advantage of lower cost (no extra interfaces or lines), but has significant security disadvantages: o saturation of customer lines or interfaces can make the device unmanageable o since public interfaces/channels are used, it is possible for Jones, Editor Expires April 24, 2004 [Page 8] Internet-Draft Operational Security Requirements October 2003 attackers to directly address and reach the device and to attempt management functions o in-band management traffic on public interfaces may be intercepted o Since the same networking code and interfaces are shared for management and customer data, it is not possible to isolate management functions from failures in other areas (for example, a "magic packet" or buffer overrun that causes the data forwarding portions of a router to crash will also likely make it impossible to manage...this would not necessarily be the case if the management and data forwarding elements were completely separated) 2.2.1 Use Encryption Algorithms Subject To Open Review Requirement. If encryption is used to satisfy the Section 2.1.1 requirements, then the encryption algorithms used MUST be subject to open review. Justification. Proprietary encryption algorithms and protocols that have not been subjected to public/peer review are more likely to have undiscovered weaknesses or flaws than open standards and publicly reviewed algorithms. Examples. For applications requiring symmetric encryption AES or 3DES satisfy the requirement. For applications requiring asymmetric encryption RSA and Elliptic Curve satisfy the requirement. For key exchange Diffie-Hellman meets the requirement. For message digests MD5 and SHA meet the requirement. Warnings. Open review is necessary but not sufficient. The strength of the algorithm and key length must also be considered. For example, 56-bit DES meets the open review requirement, but is today considered too weak and is therefore not recommended. 2.2.2 Use Strong Encryption Requirement. If encryption is used to satisfy the Section 2.1.1 requirements, then the key lengths and algorithms SHOULD be "strong". Justification. Short keys and weak algorithms threaten the confidentiality and integrity of communications. Jones, Editor Expires April 24, 2004 [Page 9] Internet-Draft Operational Security Requirements October 2003 Examples. This document explicitly does not attempt to make any authoritative statement about what key lengths and algorithms constitute "strong" encryption. The reader is encouraged to consult the literature and to seek advice from trusted third parties to determine which algorithms and key lengths provide sufficiently "strong" encryption at any given time to protect data of a given value. Warnings. "Strong" is a relative term. Long keys and strong algorithms are intended to increase the work factor required to compromise the security of the data protected. Over time, as processing power increases, the security provided by a given algorithm and key length will degrade. The definition of "Strong" must be constantly reevaluated. There may be legal issues governing the use of encryption and the strength of encryption used. 2.3 Out-of-Band (OoB) Management Requirements See Section 2.2 for a discussion of the advantages and disadvantages of In-band vs. Out-of-Band management. 2.3.1 Support a Non-IP 'Console' interface Requirement. The device MUST support complete configuration and management via a non-IP interface. Justification. There are times when the device *must* be managed or configured, even when the network is unavailable, routing and network interfaces are incorrectly configured, the IP stack and/or operating system may not be working (or may be vulnerable to recently discovered exploits that make their use impossible/ inadvisable), or when high bandwidth paths to the device are unavailable. In such situations, non-IP interfaces can provide a way to manage and configure the device. Examples. One example would be an RS232 (EIA232) interface that provides the capability to load new versions of the system software and to perform configuration via a command line interface. RS232 interfaces are ubiquitous and well understood. Warnings. None. 2.3.2 Support A Simple Default Communication Profile On The 'Console' Jones, Editor Expires April 24, 2004 [Page 10] Internet-Draft Operational Security Requirements October 2003 Requirement. The device MUST support a simple default profile of communications parameters on the Non-IP management interface. These communications parameters MUST be published in the system documentation. There SHOULD be a method defined and published for returning to the default configuration. Justification. A simple, standard profile minimizes confusion and maximizes the chances of successful and well understood recovery practices. This profile follows the principals of "least surprise" and "Be liberal in what you accept and conservative in what you send." Examples. The following is a profile widely used for RS232 console connections: the only required signals SHOULD be Transmit Data (TD), Receive Data (RD) and Signal Ground (SG). Other signals, SHOULD NOT be required (e.g. DCD, RTS, CTS, DSR, etc.). The default settings SHOULD be 9600bps, 8 bit data, no parity, one stop-bit (9600 8n1). Sending a break would be one way to signal that the communications parameters should be reset. Warnings. The default RS232 profile described above does not support hardware flow control. 2.3.3 Support Separate Management Plane IP Interfaces Requirement. The device MAY provide designated network interface(s) that are used for management plane traffic. Justification. A separate management plane interface allows management traffic to be segregated from other traffic (data/ forwarding plane, control plane). This reduces the risk that unauthorized individuals will be able to observe management traffic and/or compromise the device. This requirement applies in situations where a separate OoB management network exists. Examples. This requirement may be satisfied, for example, with a predefined Ethernet port dedicated to management and isolated from customer traffic. Warnings. The use of this type of interface depends on proper functioning of both the operating system and the IP stack, as well as good, known configuration at least on the portions of the device dedicated to management. To talk to an ethernet interface for management, you must know, for instance, it's IP address. Jones, Editor Expires April 24, 2004 [Page 11] Internet-Draft Operational Security Requirements October 2003 2.3.4 No Forwarding Between Management Plane And Other Interfaces Requirement. If the device implements separate network interface(s) for the management plane per Section 2.3.3 then the device MUST not forward traffic between the management plane and non-management plane interfaces. Justification. This prevents the flow, intentional or unintentional, of management traffic to/from places that it should not be originating/terminating (e.g. anything beyond the customer-facing interfaces). Examples. This requirement may be satisfied by implementing separate forwarding tables for management plane and non-management plane interfaces that do not propagate routes to each other. Warnings. None. 2.3.5 Provide Separate Resources For The Management Plane Requirement. If the device implements separate network interface(s) for the management plane per Section 2.3.3 then the device SHOULD provide separate resources and use separate software for different classes of interface. Justification. The use of separate resources and system software allows for fault isolation and increased reliability. If something (a hacker sending a DoS flood or exercising a buffer overrun) takes out the forwarding plane, the management plane is likely to keep working, which will facilitate recovery. Likewise, if something causes the management plane to stop working, it is possible that the forwarding plane will keep doing its job (forwarding packets). Examples. Resources which should be separate include hardware (memory, processor), data (forwarding table), and software (OS, IP stack). Warnings. None. 2.4 Configuration and Management Interface Requirements This section lists requirements that document current best practice in device configuration and management methods. In most cases, this currently involves some sort of command line interface (CLI) and configuration files. It may be possible in the future to meet the Jones, Editor Expires April 24, 2004 [Page 12] Internet-Draft Operational Security Requirements October 2003 individual requirements via other mechanisms, specifically via mechanisms currently (October 2003) being defined by the IETF netconf working group [netconf]. 2.4.1 CLI Provides Access to All Configuration and Management Functions Requirement. The Command Line Interface (CLI) or equivalent MUST allow complete access to all configuration and management functions. Justification. Restricted or incomplete access to configuration or management functions may make it impossible to perform necessary tasks. Examples. Examples of configuration include setting interface addresses, defining and applying filters, configuring logging and authentication, etc. Examples of management functions include displaying dynamic state information such as CPU load, memory utilization, packet processing statistics, etc. Warnings. None. 2.4.2 CLI Uses Existing Authentication Mechanisms Requirement. The CLI or equivalent MUST utilize existing authentication methods. Justification. The use of existing authentication methods keeps the implementation simple and avoids needless complexity. Examples. If a CLI function requires authentication functions and a remote AAA (TACACS+, RADIUS, etc.) server is in use, then the CLI should be able to use that server of authentication. Warnings. None. 2.4.3 CLI Supports Scripting of Configuration Requirement. The CLI or equivalent MUST support external scripting of configuration functions. The scripting capability MUST NOT require the use of a particular scripting language. Justification. Scripting is necessary when the number of managed devices is large and/or when changes must be implemented quickly. The ability to script configuration functions provides operators with the ability to implement solutions to problems not foreseen Jones, Editor Expires April 24, 2004 [Page 13] Internet-Draft Operational Security Requirements October 2003 or addressed by the vendor. Examples. Example uses of scripting include: tracking an attack across a large network, updating authentication parameters, updating logging parameters, updating filters, configuration fetching/auditing etc. Some languages that are currently used for scripting include expect, Perl and TCL. Some properties of the command language that enhance the ability to script are: simplicity, regularity and consistency. Warnings. None. 2.4.4 CLI Supports Management Over 'Slow' Links Requirement. The device MUST support a command line interface (CLI) or equivalent mechanism that works over low bandwidth connections Justification. There are situations where high bandwidth for management is not available, for example when in-band connections are overloaded during an attack or when low-bandwidth, out-of-band connections such as modems must be used... and it is often under these conditions that it is most crucial to be able to perform management and configuration functions. Examples. The network is down. The network engineer just disabled routing by mistake on the sole gateway router in a remote unmanned data center. The only access to the device is over a modem connected to a console port. The data center customers are starting to call the support line. The GUI management interface is redrawing the screen multiple times...slowly... at 9600bps. Warnings. One consequence of this requirement may be that requiring a GUI interface for management is unacceptable unless it can be show to work acceptably over slow links. 2.4.5 Support Software Installation Requirement. The device MUST provide a means to install new software versions. It MUST be possible to install new software while the device is disconnected from all public IP networks. This MUST NOT rely on previous installation and/or configuration. Justification. * Vulnerabilities are often discovered in the base software (operating systems, etc.) shipped by vendors. Often mitigation Jones, Editor Expires April 24, 2004 [Page 14] Internet-Draft Operational Security Requirements October 2003 of the risk presented by these vulnerabilities can only be accomplished by updates to the vendor supplied software (e.g. bug fixes, new versions of code, etc.). Without a mechanism to load new vendor supplied code, it may not be possible to mitigate the risk posed by these vulnerabilities. * It is also conceivable that malicious behavior on the part of hackers or unintentional behaviors on the part of operators could cause software on devices to be corrupted or erased. In these situations, it is necessary to have a means to (re)load software onto the device to restore correct functioning. * It is important to be able to load new software while disconnected from all public IP networks because the device may be vulnerable to old attacks before the update is complete. Examples. RS-232 The device could support uploading new code via an RS232 console port. CD-ROM The device could support installing new code from a locally attached CD-ROM drive. NETWORK The device could support installing new code via a network interface, assuming that (a) it is disconnected from all public networks and (b) the device can boot an OS and IP stack from some read-only media with sufficient capabilities to load new code from the network. Warnings. None. 2.4.6 Support Remote Configuration Backup Requirement. The device MUST provide a means to store the system configuration to a remote server. The stored configuration MUST have sufficient information to restore the device to its operational state at the time the configuration is saved. Justification. Archived configurations are essential to enable auditing and recovery. Examples. Possible implementations include SCP, SFTP or FTP over a secure channel. See Section 2.1.1 for requirements related to secure communication channels for management protocols and data. Jones, Editor Expires April 24, 2004 [Page 15] Internet-Draft Operational Security Requirements October 2003 Warnings. The security of the remote server is assumed, with appropriate measures being outside the scope of this document. 2.4.7 Support Remote Configuration Restore Requirement. The device MUST provide a means to restore a configuration that was saved as described in Section 2.4.6. The system MUST be restored to its operational state at the time the configuration was. Justification. Restoration of archived configurations allows quick restoration of service following an outage (security related as well as from other causes). Examples. Configurations may be restored using SCP, SFTP or FTP over a secure channel. See Section 2.1.1 for requirements related to secure communication channels for management protocols and data. Warnings. The security of the remote server is assumed, with appropriate measures being outside the scope of this document. 2.4.8 Support Human-Readable Configuration File Requirement. The device MUST provide a means to remotely save a copy of the system configuration file(s) in a human-readable form. It MUST NOT be necessary to use a proprietary program to view the configuration. The configuration MUST also be viewable in human readable form on the device itself. Justification. Having configurations in human-readable format is necessary to enable off-line audits of the system configuration. Having them in simple, non-proprietary formats also facilitates automation of configuration checking. Examples. A simple text-based configuration file would satisfy this requirement. Warnings. Offline copies of configurations should be well protected as they often contain sensitive information such as SNMP community strings, passwords, network blocks, customer information, etc. 2.5 IP Stack Requirements Jones, Editor Expires April 24, 2004 [Page 16] Internet-Draft Operational Security Requirements October 2003 2.5.1 Ability to Identify All Listening Services Requirement. The vendor MUST: * Provide a means to display all services that are listening for network traffic directed at the device from any external source. * Display the interfaces on which each service is listening. * Include both open standard and vendor proprietary services. Justification. This information is necessary to enable a thorough assessment of the security risks associated with the operation of the device (e.g., "does this protocol allow complete management of the device without also requiring authentication, authorization, or accounting"?). The information also assists in determining what steps should be taken to mitigate risk (e.g., "should I turn this service off "?) Examples. If, for example, the device is listening for SNMP on all interfaces, then this requirement could be met by the provision of a command which displays that fact. Warnings. None. 2.5.2 Ability to Disable Any and All Services Requirement. The device MUST provide a means to turn off any external services listening. Justification. The ability to disable services for which there is no operational need will allow administrators to reduce the overall risk posed to the device. Examples. Processes that listen on TCP and UDP ports would be prime examples of services that it must be possible to disable. Warnings. None. 2.5.3 Listening Services Should Be Off By Default Requirement. Services that cause the device to listen for traffic destined for itself SHOULD be off by default. The user SHOULD have to take explicit actions to enable any such services. Jones, Editor Expires April 24, 2004 [Page 17] Internet-Draft Operational Security Requirements October 2003 Justification. Open ports have the potential to expose vulnerabilities. The user, not the vendor, should decide which services are required and what risks to accept. This will also prevent systems from being compromised through the misuse of services which the user was unaware were enabled. Examples. If the device supports SSH, HTTP, telnet and SNMP, in the default configuration they should all be disabled. Warnings. None. 2.5.4 Ability to Control Service Bindings for Listening Services Requirement. The device MUST provide a means for the user to specify the bindings used for all listening services. It MUST support binding to a list of addresses and netblocks and SHOULD support configuration of binding services to particular interfaces, including loopback addresses. Justification. This greatly reduces the need for complex filters. It reduces the number of ports listening, and thus the number of potential avenues of attack. It ensures that only traffic arriving from legitimate addresses and/or on designated interfaces can access services on the device. Examples. If the device listens for inbound SSH connections, this requirement means that it should be possible to specify that the device will only listen to connections destined to specific addresses (e.g. the address of the loopback interface) or received on certain interfaces (e.g. an ethernet interface designated as the "management" interface). It should be possible in this example to configure the device such that the SSH is NOT listening on every interface or to every address configured on the device. Warnings. None. 2.5.5 Ability to Control Service Source Address Requirement. The device MUST provide a means that allows the user to specify the source address used for all outbound connections or transmissions originating from the device. It MUST be possible to specify source addresses independently for each type of outbound connection or transmission. Source addresses MUST be limited to addresses that are assigned to interfaces (including loopbacks) local to the device. Jones, Editor Expires April 24, 2004 [Page 18] Internet-Draft Operational Security Requirements October 2003 Justification. This allows remote devices receiving connections or transmissions to use source filtering as one means of authentication. For example, if SNMP traps were configured to use a known loopback address as their source, the SNMP workstation receiving the traps (or a firewall in front of it) could be configured to receive SNMP packets only from that address. Examples. None. Warnings. None. 2.5.6 Support Automatic Anti-spoofing for Single-Homed Networks Requirement. The device MUST provide a means to designate particular interfaces as servicing single-homed networks and MUST provide an option to automatically apply anti-spoofing to such interfaces. This option MUST work in the presence of dynamic routing and dynamically assigned addresses. It MUST NOT negatively impact performance. It MUST provide accurate counts of spoofed packets that were dropped with logging options. It SHOULD be possible to apply the option to an interface with a single command. For the purposes of this requirement a "single-homed network" is defined as one for which * There is only one (logical) upstream connection * Routing is symmetric A "spoofed packet" is defined as a "packet having a source address that, by application of the current forwarding tables, would not have its return traffic routed back through the interface on which it was received." Justification. See [RFC2867] Network Ingress Filtering. Examples. This requirement could be satisfied in several ways. It could be satisfied by the provision of a single command that automatically generates and applies filters to an interface that implements anti-spoofing. It could be satisfied by the provision of a command that causes the return path for packets received to be checked against the current routing tables and dropped if they would not be forwarded back through the interface on which they were received. Warnings. None. Jones, Editor Expires April 24, 2004 [Page 19] Internet-Draft Operational Security Requirements October 2003 2.5.7 Directed Broadcasts Disabled by Default Requirement. The default configuration of the device MUST ensure that: * It will not respond to any directed broadcasts to any broadcast domains of which it is a member. * It will not propagate any directed broadcasts to any broadcast domains to which it is directly connected. There SHOULD be a mechanism to re-enable directed broadcasts on a per-interface basis. Justification. Directed broadcasts have few legitimate uses in modern networks and are easily abused to amplify denial of service attacks (e.g., SMURF attacks). [RFC2644] recommends the same change in default settings as a Best Current Practice. Examples. None. Warnings. The requirement is in violation of [RFC1812]. 2.6 Rate Limiting Requirements 2.6.1 Support Rate Limiting Requirement. The device MUST provide the capability to limit the rate at which it will pass traffic based on protocol, port, and interface: and to rate-limit input and/or output separately on each interface. It SHOULD allow filtering on any protocol and MUST allow filtering on at least IP, ICMP, UDP, and TCP. This feature SHOULD be implemented with minimal impact to system performance. Justification. This requirement provides a means of reducing or eliminating the impact of certain types of attacks. Examples. Assume that a web hosting company provides space in its data-center to a company that becomes unpopular with a certain element of network users, who then decide to flood the web server with inbound ICMP traffic. It would be useful in such a situation to be able to rate-filter inbound ICMP traffic at the data-center's border routers. On the other side, assume that a new worm is released that infects vulnerable database servers such that they then start spewing traffic on TCP port 1433 aimed at random destination addresses as fast as the system and network Jones, Editor Expires April 24, 2004 [Page 20] Internet-Draft Operational Security Requirements October 2003 interface of the infected server is capable. Further assume that a data center has many vulnerable servers that are infected and simultaneously sending large amounts of traffic with the result that all outbound links are saturated. Implementation of this requirement, would allow the network operator to rate limit inbound and/or outbound TCP 1433 traffic (possibly to a rate of 0 packets/bytes per second) to respond to the attack and maintain service levels for other legitimate customers/traffic. Warnings. None. 2.6.2 Support Rate Limiting Based on State Requirement. For stateful protocols it SHOULD be possible to rate limit traffic based on session state. Justification. This allows appropriate response to certain classes of attack. Examples. For example, for TCP sessions, it should be possible to rate limit based on the SYN, SYN-ACK, RST, or other bit state. Warnings. None. 2.7 Basic Filtering Capabilities 2.7.1 Ability to Filter Traffic Requirement. The device MUST provide a means to filter IP packets on any interface implementing IP. In this document a "filter" is defined as a group of one or more rules where each rule specifies one or more match criteria as specified in Section 2.8. Also see the specific filtering requirements that follow this one. Justification. Packet filtering is important because it provides a basic means of implementing policies that specify which traffic is allowed and which is not. It also provides a basic tool for responding to malicious traffic. Examples. Access control lists that allow filtering based on protocol and/or source/destination address and or source/destination port would be one example. Jones, Editor Expires April 24, 2004 [Page 21] Internet-Draft Operational Security Requirements October 2003 Warnings. None. 2.7.2 Ability to Filter Traffic TO the Device Requirement. It MUST be possible to apply the filtering mechanism to traffic that is addressed directly to the device via any of its interfaces - including loopback interfaces. Justification. This is important because it allows filters to be applied that protect the device itself from attacks and unauthorized access. Examples. Examples of this might include filters that permit only SNMP and SSH traffic from an authorized management segment directed to the device itself, while dropping all other traffic addressed to the device. Warnings. None. 2.7.3 Ability to Filter Traffic THROUGH the Device Requirement. It MUST be possible to apply the filtering mechanism to traffic that is being routed (switched) through the device. Justification. This is important because it permits implementation of basic policies on devices that carry transit traffic (routers, switches, firewalls, etc.). Examples. One simple and common way to meet this requirement is to provide the ability to filter traffic inbound to each interface and/or outbound from each interface. Ingress filtering as described in [RFC2827] provides one example of the use of this capability. Warnings. None. 2.7.4 Ability to Filter Without Performance Degradation Requirement. The device MUST provide a means to filter packets without performance degradation. The device MUST be able to filter on ALL interfaces (up to the maximum number possible) simultaneously and with multiple filters per interface (e.g., inbound and outbound). Jones, Editor Expires April 24, 2004 [Page 22] Internet-Draft Operational Security Requirements October 2003 Justification. This is important because it enables the implementation of filtering wherever and whenever needed. To the extent that filtering causes degradation, it may not be possible to apply filters that implement the appropriate policies. Examples. Another way of stating the requirement is that filter performance should not be the limiting factor in device throughput. If a device is capable of forwarding, say, 30Mb/sec without filtering, then it should be able to forward the same amount with filtering in place. This requirement most likely implies a hardware-based solution (ASIC). Warnings. Without hardware based filtering, it may be possible for the implementation of filters to degrade the performance of the device or to cause it to cease functioning. 2.7.5 Ability to Filter Updates Requirement. The device MUST provide a means to filter updates for all protocols that could be used to update operational characteristics of the device. Note that it MUST be possible to specify a filter that disables all updates. This requirement MAY be satisfied through the use of filters as described in Section 2.7.1 and/or with mechanisms specific to each protocol. Also note that update filtering is required in addition to secure channels (Section 2.1.1) and authentication (Section 2.12) Justification. Without the ability to filter protocols used for management and operational updates, unauthorized users might be able to change operational parameters (e.g., routing tables, passwords, etc.) and/or completely disable the device. Examples. This should include the ability to: * Filter routing protocol updates * Disable SNMP writing completely * Filter addresses permitted to manage the device regardless of protocol (SNMP,SSH,TELNET,HTTP,TFTP,SNMP...) Warnings. None. Jones, Editor Expires April 24, 2004 [Page 23] Internet-Draft Operational Security Requirements October 2003 2.7.6 Ability to Specify Filter Actions Requirement. The device MUST provide a mechanism to allow the specification of the action to be taken when a filter rule matches. Actions must include "permit" (allow the traffic), "reject" (drop with appropriate notification to sender), and "drop" (drop with no notification to sender). Also see Section 2.7.7 and Section 2.9 Justification. This capability is essential to the use of filters to enforce policy. Examples. Assume that you have a small DMZ network connected to the Internet. You want to allow management using SSH coming from your corporate office. In this case, you might "permit" all traffic to port 22 in the DMZ from your corporate network, "rejecting" all others. Port 22 traffic from the corporate network is allowed through. Port 22 traffic from all other addresses results in an ICMP message to the sender. For those who are slightly more paranoid, you might choose to "drop" instead of "reject" traffic from unauthorized addresses, with the result being that *nothing* is sent back to the source. Warnings. [Ed. Does "drop" with no ICMP unreachable violate any RFCs ?] 2.7.7 Ability to Log Filter Actions Requirement. It MUST be possible to log all filter actions. The logging capability MUST be able to capture at least the following data: permit/deny/drop status, source and destination ports, source and destination IP address, which network element forwarded the packet (interface, MAC address or other layer 2 information that identifies the previous hop source of the packet), and time-stamp to millisecond accuracy. Logging of filter actions is subject to the requirements of Section 2.11. Justification. Logging is essential for auditing, incident response, and operations. Examples. A desktop network may not provide any services that should be accessible from "outside." In such cases, all inbound connection attempts should be logged as possible intrusion Jones, Editor Expires April 24, 2004 [Page 24] Internet-Draft Operational Security Requirements October 2003 attempts. Warnings. None. 2.8 Packet Filtering Criteria 2.8.1 Ability to Filter on Protocols Requirement. The device MUST provide a means to filter traffic based on protocol. Justification. Being able to filter on protocol is necessary to allow implementation of policy, secure operations and for support of incident response. Examples. Some denial of service attacks are based on the ability to flood the victim with ICMP traffic. One quick way (admittedly with some negative side effects) to mitigate the effects of such attacks is to drop all ICMP traffic headed toward the victim. Warnings. None. 2.8.2 Ability to Filter on Addresses Requirement. The function MUST be able to control the flow of traffic based on source and/or destination IP address or blocks of addresses such as Classless Inter-Domain Routing (CIDR) blocks. Justification. The capability to filter on addresses and address blocks is a fundamental tool for establishing boundaries between different networks. Examples. One example of the use of address based filtering is to implement ingress filtering per [RFC2827]. Warnings. None. 2.8.3 Ability to Filter on Any Protocol Header Fields Requirement. The filtering mechanism MUST support filtering based on the value(s) of any portion of the protocol headers. Justification. Being able to filter on portions of the header is necessary to allow implementation of policy, secure operations, and support incident response. Jones, Editor Expires April 24, 2004 [Page 25] Internet-Draft Operational Security Requirements October 2003 Examples. For example, this requirement implies that it is possible to filter based on TCP or UDP port numbers, TCP flags such as SYN, ACK and RST bits, and ICMP type and code fields. One common example is to reject "inbound" TCP connection attempts (TCP, SYN bit set). Another common example is the ability to control what services are allowed in/out of a network. For example, it may be desirable to only allow inbound connections on port 80 (HTTP) and 443 (HTTPS) to a network hosting web servers. Warnings. None. 2.8.4 Ability to Filter Inbound and Outbound Requirement. It MUST be possible to filter both incoming and outgoing traffic on any interface. Justification. This requirement allows flexibility in applying filters at the place that makes the most sense. It allows invalid or malicious traffic to be dropped as close to the source as possible. Examples. It might be desirable on a border router, for example, to apply an egress filter outbound on the interface that connects a site to its external ISP to drop outbound traffic that does not have a valid internal source address. Inbound, it might be desirable to apply a filter that blocks all traffic from a site that is known to forward or originate lots of junk mail. Warnings. None. 2.9 Packet Filtering Counter Requirements 2.9.1 Ability to Accurately Count Filter Hits Requirement. The device MUST supply a facility for accurately counting all filter hits. Justification. Accurate counting of filter rule matches is important because it shows the magnitude/frequency of attempts to violate policy. This enables resources to be focused on areas of greatest need. Examples. Assume, for example, that a ISP network implements anti-spoofing egress filters (see [RFC2827]) on interfaces of its edge routers that support single-homed stub networks. Counters could enable the ISP to detect cases where large numbers of Jones, Editor Expires April 24, 2004 [Page 26] Internet-Draft Operational Security Requirements October 2003 spoofed packets are being sent. This may indicate that the customer is performing potentially malicious actions (possibly in violation of the IPS's Acceptable Use Policy), or that system(s) on the customers network have been "owned" by hackers and are being (mis)used to launch attacks. Warnings. None. 2.9.2 Ability to Display Filter Counters Requirement. The device MUST provide a mechanism to display filter counters. Justification. Information that is collected is not useful unless it can be displayed in a useful manner. Examples. Assume there is a router with four interfaces. One is an up-link to an ISP providing routes to the Internet. The other three connect to separate internal networks. Assume that a host on one of the internal networks has been compromised by a hacker and is sending traffic with bogus source addresses. In such a situation, it might be desirable to apply ingress filters to each of the internal interfaces. Once the filters are in place, the counters can be examined to determine the source (inbound interface) of the bogus packets. Warnings. None. 2.9.3 Ability to Display Filter Counters per Rule Requirement. The device MUST provide a mechanism to display filter counters per rule. Justification. This makes it possible to see which rules are matching and how frequently. Examples. Assume that a filter has been defined that has two rules, one permitting all SSH traffic (tcp/22) and the second dropping all remaining traffic. If three packets are directed toward/ through the point at which the filter is applied, one to port 22, the others to different ports, then the counter display should show 1 packet matching the permit tcp/22 rule and 2 packets matching the deny all others rule. Jones, Editor Expires April 24, 2004 [Page 27] Internet-Draft Operational Security Requirements October 2003 Warnings. None. 2.9.4 Ability to Display Filter Counters per Filter Application Requirement. If it is possible for a filter to be applied more than once at the same time, then the device MUST provide a mechanism to display filter counters per filter application. Justification. It may make sense to apply the same filter definition simultaneously more than one time (to different interfaces, etc.). If so, it would be much more useful to know which instance of a filter is matching than to know that some instance was matching somewhere. Examples. One way to implement this requirement would be to have the counter display mechanism show the interface (or other entity) to which the filter has been applied, along with the name (or other designator) for the filter. For example if a filter named "desktop_outbound" applied two different interfaces, say, "ethernet0" and "ethernet1," the display should indicate something like "matches of filter 'desktop_outbound' on ethernet0 ..." and "matches of filter 'desktop_outbound' on ethernet1 ..." Warnings. None. 2.9.5 Ability to Reset Filter Counters Requirement. It MUST be possible to reset counters to zero on a per filter basis. Justification. This allows operators to get a current picture of the traffic matching particular rules/filters. Examples. Assume that filter counters are being used to detect internal hosts that are infected with a new worm. Once it is believed that all infected hosts have been cleaned up and the worm removed, the next step would be to verify that. One way of doing so would be to reset the filter counters to zero and see if traffic indicative of the worm has ceased. Warnings. None. 2.9.6 Filter Counters Must Be Accurate Jones, Editor Expires April 24, 2004 [Page 28] Internet-Draft Operational Security Requirements October 2003 Requirement. Filter counters MUST be accurate. They MUST reflect the actual number of matching packets since the last counter reset. Justification. Inaccurate data can not be relied on as the basis for action. Underreported data can conceal the magnitude of a problem. Examples. If N packets matching a filter are sent to/through a device, then the counter should show N matches. Warnings. None. 2.10 Other Packet Filtering Requirements 2.10.1 Filter, Counters, and Filter Log Must Have Minimal Performance Impact Requirement. Filtering, logging, and counting functionality MUST be implemented such that they have minimal impact on performance. Justification. The possibility of severe performance degradation in the use of filtering, logging, or counting would reduce their utility. Fear of adverse operational consequences might cause operators to limit or discard their use completely in situations where they are needed. Examples. Assume, for example, that a new worm is released that scans random IP addresses looking for services listening on TCP port 1433. An operator might want to investigate to see if any of the hosts on their networks were infected and trying to spread the worm. One way to do this would be to put up non-blocking filters counting and logging the number of outbound connection 1433, and then to block the requests that are determined to be from infected hosts. If any of these capabilities (filtering, counting, logging) have the potential to impose severe performance penalties, then this otherwise rational course of action might not be possible. Some examples of things that would make the logging features unusable might include situations where their use: * crashes the device * consumes excessive resources (CPU, memory, bandwidth) * makes the device unmanageable Jones, Editor Expires April 24, 2004 [Page 29] Internet-Draft Operational Security Requirements October 2003 * causes the loss of data Warnings. While there are some objective measures that indicate clearly when a feature is unusable (its use crashes the device), "usability" is largely a subjective term. Lab tests may be constructed to determine how well the device behaves under certain loads, but the ultimate test of usability for filtering, counting and logging will come under live, quite possibly heavy, loads. 2.10.2 Ability to Specify Filter Log Granularity Requirement. It MUST be possible to enable/disable logging on a per rule basis. Justification. The ability to tune the granularity of logging allows the operator to log only the information that is desired. Without this capability, it is possible that extra data (or none at all) wold be logged, making it more difficult to find relevant information. Examples. If a filter is defined that has several rules, and one of the rules denies telnet (tcp/23) connections, then it should be possible to specify that only matches on the rule that denies telnet should generate a log message. Warnings. None. 2.11 Event Logging Requirements 2.11.1 Logging Facility Conforms to Open Standards Requirement. The device MUST provide a logging facility that conforms to open standards. Custom/Proprietary log protocols MAY be implemented provided the same information is made available via logging facilities that conform to open standards. Justification. The use of open standards logging is important because it permits the customer to perform archival and analysis of logs without relying on vendor-supplied software and servers. Examples. [RFC3195] meets this requirement. The use of SNMP traps may also satisfy this requirement. Jones, Editor Expires April 24, 2004 [Page 30] Internet-Draft Operational Security Requirements October 2003 Warnings. While [RFC3164] and SNMP may satisfy this requirement, they both fail to satisfy several other logging requirements. 2.11.2 Ability to Log to Remote Server Requirement. The device MUST be capable of logging to a remote server. It SHOULD be able to log to multiple servers. Justification. External logging allows the storage of large, persistent logs that may not be possible with local (on the device) logging. Examples. One example of a remote log server would be a host running a syslog server. See [RFC3164]. Warnings. High volumes of logging may generate excessive network traffic and/or compete for scarce memory and CPU resources on the device. 2.11.3 Ability to Log Locally Requirement. It SHOULD be possible to log locally on the device itself. Justification. Local logging is important for viewing information when connected to the device. It provides some backup of log data in case remote logging fails. It provides a way to view logs relevant to one device without having to sort through a possibly large set of logs from other devices. Examples. One example of local logging would be a memory buffer that receives copies of messages sent to the remote log server. Another example might be a local syslog server (assuming the device is capable of running syslog and has some local storage). Warnings. Storage on the device may be limited. High volumes of logging may quickly fill available storage, in which case there are two options: new logs overwrite old logs (possibly via the use of a circular memory buffer or log file rotation), or logging stops. 2.11.4 Ability to Maintain Accurate System Time Jones, Editor Expires April 24, 2004 [Page 31] Internet-Draft Operational Security Requirements October 2003 Requirement. The device MUST maintain accurate, high resolution system time. All displays of system time MUST include a timezone. The default timezone SHOULD be UTC or GMT. The device SHOULD support a mechanism to allow the operator to specify the timezone for local system time. Justification. This is important because the system clock is used for time-stamping log messages. Examples. This requirement may be satisfied by supporting Network Time Protocol (NTP), Simple Network Time Protocol (SNTP), or via direct connection to an accurate time source. See Section 2.1.1 for requirements related to secure communication channels for management protocols and data. Warnings. System clock chips are inaccurate to varying degrees. System time should not be relied upon unless it is regularly checked and synchronized with a known, accurate external time source (such as an NTP stratum-1 server). Also note that if network time synchronization is used, an attacker may be able to manipulate the clock unless cryptographic authentication is used. 2.11.5 Logs Must Be Timestamped Requirement. The device MUST time-stamp all log messages. The time-stamp MUST be accurate to within a second or less. The time-stamp MUST include a timezone. Justification. This is important because accurate timestamps are necessary for correlating events, particularly across multiple devices or with other organizations. This applies when it is necessary to analyze logs. Examples. This requirement MAY be satisfied by writing timestamps into syslog messages. Warnings. It is difficult to correlate logs from different time zones. Security events on the Internet often involve machines and logs from a variety of physical locations. For that reason, UTC is preferred, all other things being equal. 2.11.6 Logs Contain Untranslated Addresses Requirement. Log messages MUST contain relevant IP addresses. Jones, Editor Expires April 24, 2004 [Page 32] Internet-Draft Operational Security Requirements October 2003 Justification. It is important to include IP address of access list violation logs, authentication attempts. This enables a level of individual and organizational accountability and is necessary to enable analysis of network events, incidents, policy violations, etc. Examples. None. Warnings. * Source addresses may be spoofed. Network-based attacks often use spoofed source addresses. Source addresses should not be completely trusted unless verified by means. * Addresses may be reassigned to different individual, for example, in a desktop environment using DHCP. In such cases the individual accountability afforded by this requirement is weak. * Network topologies may change. Even in the absence of dynamic address assignment, network topologies and address block assignments do change. Logs of an attack one month ago may not give an accurate indication of which host, network or organization owned the system(s) in question at the time. 2.12 Authentication, Authorization, and Accounting (AAA) Requirements 2.12.1 Authenticate All User Access Requirement. The device MUST provide a facility to perform authentication of all user access to the system. Justification. This functionality is required so that access to the system can be restricted to authorized personnel. Examples. This requirement MAY be satisfied by implementing a centralized authentication system. See Section 2.12.5. It MAY also be satisfied using local authentication. See Section 2.12.6 Warnings. None. 2.12.2 Support Authentication of Individual Users Requirement. Each authentication mechanism supported by the device MUST support the authentication of distinct, individual users. Jones, Editor Expires April 24, 2004 [Page 33] Internet-Draft Operational Security Requirements October 2003 Justification. The use of individual accounts, in conjunction with logging, promotes accountability. The use of group or default accounts undermines individual accountability. Examples. The implementation depends on the types of authentication supported by the device. Local usernames and passwords are one possibility. Centralized authentication servers using usernames and onetime passwords is another. Warnings. This simply requires that the mechanism to support individual users be present. Policy (e.g., forbidding shared group accounts) and enforcement are also needed but beyond the scope of this document. 2.12.3 Support Simultaneous Connections Requirement. The device SHOULD support multiple simultaneous connections by distinct users, possibly at different authorization levels. Justification. This allows multiple people to perform authorized management functions simultaneously. Examples. None. Warnings. None. 2.12.4 Ability to Disable All Local Accounts Requirement. The device MUST provide a means of disabling all local accounts including: * Local users * Default accounts (vendor, maintenance, guest...) * Privileged and unprivileged accounts Justification. Default accounts, well-know accounts, and old accounts provide easy targets for someone attempting to gain access to a device. It must be possible to disable them to reduce the potential vulnerability. Examples. The implementation depends on the types of authentication supported by the device. Jones, Editor Expires April 24, 2004 [Page 34] Internet-Draft Operational Security Requirements October 2003 Warnings. None. 2.12.5 Support Centralized User Authentication Methods Requirement. The device MUST support a method of centralized authentication of all user access via standard authentication protocols. Justification. Support for centralized authentication is particularly important in large environments where the network devices are widely distributed and where many people have access to them. This reduces the effort needed to effectively restrict and track access to the system by authorized personnel. Examples. Terminal Access This requirement can be satisfied through the use of Terminal Controller Access Control System Plus (TACACS+), Remote Authentication Dial-In User Service (RADIUS), or Kerberos. See Section 2.1.1 for requirements related to secure communication channels for management protocols and data. Warnings. None. 2.12.6 Support Local User Authentication Method Requirement. The device SHOULD support a local authentication method. If implemented, the method MUST NOT require interaction with anything external to the device (such as remote AAA servers), and MUST work in conjunction with Section 2.3.1 (Support a Non-IP 'Console' interface) and Section 2.12.7 (Support Configuration of Order of Authentication Methods). Justification. Support for local authentication may be required in smaller environments where there may be only a few devices and a limited number of people with access. The overhead of maintaining centralized authentication servers may not be justified. Examples. The use of local, per-device usernames and passwords provides one way to implement this requirement. Warnings. Authentication information must be protected wherever it resides. Having, for instance, local usernames and passwords stored on 100 network devices means that there are 100 potential points of failure where the information could be compromised vs. storing authentication data centralized server(s), which would reduce the potential points of failure to the number of servers and allow protection efforts (system hardening, audits, etc.) to Jones, Editor Expires April 24, 2004 [Page 35] Internet-Draft Operational Security Requirements October 2003 be focused on, at most, a few servers. 2.12.7 Support Configuration of Order of Authentication Methods Requirement. The device MUST support the ability to configure the order in which supported authentication methods are attempted. Authentication SHOULD "fail closed", i.e. access should be denied if none of the listed authentication methods succeeds. Justification. This allows the operator flexibility in implementing appropriate security policies that balance operational and security needs. Examples. If, for example, a device supports RADIUS authentication and local usernames and passwords, it should be possible to specify that RADIUS authentication should be attempted if the servers are available, and that local usernames and passwords should be used for authentication only if the RADIUS servers are not available. Similarly, it should be possible to specify that only RADIUS or only local authentication be used. Warnings. None. 2.12.8 No Unencrypted Transmission of Reusable Plain-text Passwords Requirement. The device MUST perform authentication without the unencrypted transmission of reusable plain-text passwords across a network. The implementation: * MUST NOT cause significant performance degradation * MUST NOT require additional devices (e.g., encryption cards, etc.) * MUST scale well/be supportable on large numbers of devices (e.g., the number of keys and configuration settings that need to be managed should increase at most linearly as the number of devices). This requirement MAY be satisfied by tunneling protocols that use plain-text passwords over secure channels per Section 2.1.1. Justification. Reusable plain-text passwords can easily be observed using packet sniffers on shared networks. Mechanisms that impose too high of an overhead or are not manageable will not be used. This requirement specifically precludes the use of reusable Jones, Editor Expires April 24, 2004 [Page 36] Internet-Draft Operational Security Requirements October 2003 passwords with standard telnet without being carried over a secure channel (see Section 2.1.1) for device management. It does allow the use of standard telnet with one time passwords. Note that this does not preclude the use of extra hardware; it simply says that additional hardware (smart cards, encryption cards, etc.) must not be required to support authentication without the use of clear text passwords. See [RFC1704] for a through discussion of the issues. Examples. None. Warnings. None. 2.12.9 No Default Passwords Requirement. The initial configuration of the device MUST NOT contain any default passwords or similar static authentication tokens. "Similar static authentication tokens" includes any form of shared secret, public or private key. Justification. Default passwords provide an easy way for attackers to gain unauthorized access to the device. Examples. Passwords such as the name of the vendor, device, "default" etc. are easily guessed. The SNMP community strings "public" and "private" are well known defaults that provide read and write access to devices. Warnings. Lists of default passwords for various devices are readily available at numerous websites. 2.12.10 Passwords Must Be Explicitly Configured Prior To Use Requirement. The device MUST require the operator to explicitly configure passwords and similar static authentication tokens prior to use. "Similar authentication tokens" includes any form of shared secret, public or private key. Justification. This requirement is intended to prevent unauthorized management access. Requiring the operator to explicitly configure passwords will tend to have the effect of ensuring a diversity of passwords. It also shifts the responsibility for password selection to the user. Jones, Editor Expires April 24, 2004 [Page 37] Internet-Draft Operational Security Requirements October 2003 Examples. Assume that a device comes with console port for management and a default administrative account. This requirement together with No Default Passwords says that the administrative account should come with no password configured. One way of meeting this requirement would be to have the device require the operator to choose a password for the administrative account as part of a dialog the first time the device is configured. Warnings. While this device requires operators to set passwords, it does not prevent them from doing things such as using scripts to configure 100s of devices with the same easily guessed passwords. 2.12.11 Ability to Define Privilege Levels Requirement. It MUST be possible to define arbitrary subsets of all management and configuration functions and assign them to groups or "privilege levels," which can be assigned to users per Section 2.12.12 Justification. This requirement supports the implementation of the principal of "least privilege", which states that an individual should only have the privileges necessary to execute the operations he/she is required to perform. Examples. Examples of privilege levels might include "default," which allows read-only access to device configuration and operational statistics, "root/superuser/administrator" which allows update access to all configurable parameters, and "operator" which allows updates to a limited, user defined set of parameters. Note that privilege levels may be defined locally on the device or on centralized authentication servers. Warnings. None. 2.12.12 Ability to Assign Privilege Levels to Users Requirement. The device MUST be able to assign a defined set of authorized functions, or "privilege level," to each user once they have authenticated themselves the device. Privilege level determines which functions a user is allowed to execute. Also see See Section 2.12.11. Justification. This requirement supports the implementation of the principal of "least privilege," which states that an individual should only have the privileges necessary to execute the operations he/she is required to perform. Jones, Editor Expires April 24, 2004 [Page 38] Internet-Draft Operational Security Requirements October 2003 Examples. The implementation of this requirement will obviously be closely coupled with the authentication mechanism. So for example, if RADIUS is used, an attribute could be set in the user's RADIUS profile that can be used to map the ID to a certain privilege level. Warnings. None. 2.12.13 Default Privilege Level Must Be Read Only Requirement. The default privilege level MUST only allow read access to device settings and operational parameters. Justification. This requirement supports the implementation of the principal of "least privilege," which states that an individual should only have the privileges necessary to execute the operations he/she is required to perform. Examples. None. Warnings. None. 2.12.14 Change in Privilege Levels Requires Re-Authentication Requirement. The device MUST re-authenticate a user prior to granting any change in user authorizations. Justification. This requirement insures that users are able to perform only authorized actions. Examples. This requirement might be implemented by assigning base privilege levels to all users and allowing the user to request additional privileges, with the requests validated by the AAA server. Warnings. None. 2.12.15 Support Recovery Of Privileged Access Requirement. The device MUST support a mechanism to allow authorized individuals to recover full privileged administrative access in the event that access is lost. Use of the mechanism MUST require physical access to the device. There MAY be a mechanism for disabling the recovery feature. Jones, Editor Expires April 24, 2004 [Page 39] Internet-Draft Operational Security Requirements October 2003 Justification. There are times when local administrative passwords are forgotten, when the only person who knows them leaves the company, or when hackers set or change the password. In all these cases, legitimate administrative access to the device is lost. There should be a way to recover access. Requiring physical access to invoke the procedure makes it less likely that it will be abused. Some organizations may want an even higher level of security and be willing to risk total loss of authorized access by disabling the recovery feature, even for those with physical access. Examples. Some examples of ways to satisfy this requirement are to have the device give the user the chance to set a new administrative password when: The user sets a jumper on the system board to a particular position. The user sends a special sequence to the RS232 console port during the initial boot sequence. The user sets a "boot register" to a particular value. Warnings. This mechanism, by design, provides a "back door" to complete administrative control of the device and may not be appropriate for environments where those with physical access to the device can not be trusted. 2.12.16 Accounting Records Requirement. The device MUST be able to store a record of at least the following events: * Failed logins * Successful logins * All Commands executed by the user during their session, including via the management/serial port and interactions with an underlying OS (e.g., Unix "shell" commands) * Change in privilege level * All logouts Jones, Editor Expires April 24, 2004 [Page 40] Internet-Draft Operational Security Requirements October 2003 The device MUST support transmission of accounting records to one or more remote devices. There MUST be configuration settings on the device that allow selection of servers. Justification. This is important because it supports individual accountability by providing a record of changes that were made and who made them. It is important to store them on a separate server to preserve them in case of failure or compromise of the managed device. Examples. This requirement MAY be satisfied by the use of RADIUS,TACACS+, or syslog. See Section 2.1.1 for requirements related to secure communication channels for management protocols and data. Warnings. Syslog is known to be unreliable/lossy during network transmission (due to use of UDP). It has also been observed that some devices lose a significant number of UDP packets before they are ever transmitted, due (apparently) to low prioritization of the internal processing of UDP packets. Similar problems have been observed in various syslog servers (syslogd on UNIX systems). Bottom line: be aware that syslog data may be lost at one of several points. 2.13 Layer 2 Devices Must Meet Higher Layer Requirements Requirement. If a device provides layer 2 services that are dependent on layer 3 or greater services, then the portions that operate at or above layer 3 MUST conform to the requirements listed in this document. Justification. All layer 3 devices have similar security needs and should be subject to similar requirements. Examples. For example, signaling protocols required for layer 2 switching may exchange information with other devices using layer 3 communications. In such cases, the device must provide a secure layer 3 facility. Also, if higher layer capabilities (say, SSH or SNMP) are used to manage a layer 2 device, then the rest of the requirements in this document apply to those capabilities. Warnings. None. Jones, Editor Expires April 24, 2004 [Page 41] Internet-Draft Operational Security Requirements October 2003 3. Documentation Requirements The requirements in this section are intended to list information that will assist operators in evaluating and securely operating a device. 3.1 Document Listening Services Requirement. The vendor MUST: * Provide a documented explanation for all network services that may be active on the system. * Concisely document which features enable listening ports on the device. * List which services are on by default. This information MUST be provided in a single, contiguous section of the documentation. This list MUST include both open standard and vendor proprietary services. Justification. This information is necessary to enable a thorough assessment of the security risks associated with the operation of the device (e.g., "does this protocol allow complete management of the device without also requiring authentication, authorization, or accounting"?). The information also assists in determining what steps should be taken to mitigate risk (e.g., "should I turn this service off "?) Examples. This documentation should include at least a list of all possible network services that could be activated to listen on any TCP and/or UDP port, or any vendor-proprietary port/protocol. Warnings. None. Jones, Editor Expires April 24, 2004 [Page 42] Internet-Draft Operational Security Requirements October 2003 4. Assurance Requirements The requirements in this section are intended to o identify behaviors and information that will increase confidence that the device will meet the security functional requirements. o Provide information that will assist evaluation 4.1 Comply With Relevant IETF RFCs on All Protocols Implemented Requirement. The default configuration of the device MUST fully comply with IETF RFCs for all protocols implemented. "Compliance" is defined in terms of [RFC2119]. The device MUST conform to the absolute requirements. Any optional or recommended functionality implemented MUST be in conformance with the RFC. The device MAY provide means by which it can be configured in ways that are not compliant with the RFCs (for instance, if conformance is determined to be insecure). Justification. A device must first perform its primary function correctly. Once it is proven to perform its primary function, it makes sense to ask if it does/can perform securely. For Internet connected devices, compliance with RFCs provides a minimum level of assurance that the device will function as intended and inter-operate as part of an operational network. Failure to comply with RFCs calls correct functioning into question and makes the determination of secure functioning a secondary concern. Examples. Some of the relevant RFCs include: ICMP. [RFC0792] INTERNET CONTROL MESSAGE PROTOCOL [RFC1812] Requirements for IP Version 4 Routers IP. [RFC0791] INTERNET PROTOCOL [RFC0922] BROADCASTING INTERNET DATAGRAMS IN THE PRESENCE OF SUBNETS [RFC1812] Requirements for IP Version 4 Routers Jones, Editor Expires April 24, 2004 [Page 43] Internet-Draft Operational Security Requirements October 2003 [RFC1858] Security Considerations for IP Fragment Filtering [RFC2644] Changing the Default for Directed Broadcasts in Routers [RFC2827] Network Ingress Filtering TCP. [RFC0793] TRANSMISSION CONTROL PROTOCOL [RFC1858] Security Considerations for IP Fragment Filtering [RFC1948] Defending Against Sequence Number Attacks UDP. [RFC0768] User Datagram Protocol [RFC1122] Requirements for Internet Hosts -- Communication Layers [RFC1812] Requirements for IP Version 4 Routers Warnings. None. 4.2 Identify Origin of IP Stack Requirement. The vendor MUST disclose the origin or basis of the IP stack used on the system. Justification. This information is required to better understand the possible security vulnerabilities that may be inherent in the IP stack. Examples. For example, "The IP stack was derived from BSD 4.4," or "The IP stack was implemented from scratch." Warnings. Many IP stacks make simplifying assumptions about how an IP packet should be formed. A malformed packet can cause unexpected behavior in the device, such as a system crash or buffer overflow which could result in unauthorized access to the system. 4.3 Identify Origin of Operating System Jones, Editor Expires April 24, 2004 [Page 44] Internet-Draft Operational Security Requirements October 2003 Requirement. The vendor MUST disclose the origin or basis of the operating system (OS). Justification. This information is required to better understand the security vulnerabilities that may be inherent to the OS based on its origin. Examples. For example, "The operating system is based on Linux kernel 2.4.18." Warnings. None. Jones, Editor Expires April 24, 2004 [Page 45] Internet-Draft Operational Security Requirements October 2003 5. Security Considerations Security is the subject matter of this entire memo. It might be more appropriate to list operational considerations. Operational issues are mentioned as needed in the examples and warnings sections of each requirement. Jones, Editor Expires April 24, 2004 [Page 46] Internet-Draft Operational Security Requirements October 2003 References [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, August 1980. [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, September 1981. [RFC0792] Postel, J., "Internet Control Message Protocol", STD 5, RFC 792, September 1981. [RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC 793, September 1981. [RFC0922] Mogul, J., "Broadcasting Internet datagrams in the presence of subnets", STD 5, RFC 922, October 1984. [RFC1122] Braden, R., "Requirements for Internet Hosts - Communication Layers", STD 3, RFC 1122, October 1989. [RFC1704] Haller, N. and R. Atkinson, "On Internet Authentication", RFC 1704, October 1994. [RFC1812] Baker, F., "Requirements for IP Version 4 Routers", RFC 1812, June 1995. [RFC1858] Ziemba, G., Reed, D. and P. Traina, "Security Considerations for IP Fragment Filtering", RFC 1858, October 1995. [RFC1948] Bellovin, S., "Defending Against Sequence Number Attacks", RFC 1948, May 1996. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2644] Senie, D., "Changing the Default for Directed Broadcasts in Routers", BCP 34, RFC 2644, August 1999. [RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering: Defeating Denial of Service Attacks which employ IP Source Address Spoofing", BCP 38, RFC 2827, May 2000. [RFC2867] Zorn, G., Aboba, B. and D. Mitton, "RADIUS Accounting Modifications for Tunnel Protocol Support", RFC 2867, June 2000. [RFC3164] Lonvick, C., "The BSD Syslog Protocol", RFC 3164, August Jones, Editor Expires April 24, 2004 [Page 47] Internet-Draft Operational Security Requirements October 2003 2001. [RFC3195] New, D. and M. Rose, "Reliable Delivery for syslog", RFC 3195, November 2001. [netconf] IETF, "Network Configuration Working Group", 2003, . Author's Address George M. Jones, Editor The MITRE Corporation 7525 Colshire Dr., WEST McLean, VA 22102 U.S.A. Phone: +1 703 488 9740 EMail: gmjones@mitre.org URI: http://www.port111.com/opsec/ Jones, Editor Expires April 24, 2004 [Page 48] Internet-Draft Operational Security Requirements October 2003 Appendix A. Requirement Profiles This Appendix lists different profiles. A profile is a list of list of requirements that apply to a particular class of devices. The minimum requirements profile applies to all devices. A.1 Minimum Requirements Profile The functionality listed here represents a bare minimum set of requirements which any managed networking infrastructure device should adhere to. This includes all core and edge devices which are part of an IP network (such as routers, and switches). Note that SOHO equipment (typically DSL modem/routers, cable modem/routers, etc) and wireless networking infrastructure equipment have their own set of requirements and are not expected to adhere to this particular set of minimal requirements. The minimal requirements profile addresses functionality which will provide reasonable capabilities to manage the devices in the event of attacks, simplify troubleshooting, keep track of events which affect system integrity, help analyze causes of attacks, as well as provide administrators control over IP addresses and protocols to help mitigate the most common attacks and exploits. A.1.1 Functional Requirements A.1.1.1 Device Management Requirements o Support Secure Management Channels A.1.1.2 In-Band Management Requirements The following requirements apply only if In-Band management is used to satisfy Section 2.1.1 (Support Secure Management Channels) o Use Encryption Algorithms Subject To Open Review o Use Strong Encryption A.1.1.3 Out-of-Band (OoB) Management Requirements The following requirements apply only if Out-of-Band management is used to satisfy Section 2.1.1 (Support Secure Management Channels) o Support a Non-IP 'Console' interface Jones, Editor Expires April 24, 2004 [Page 49] Internet-Draft Operational Security Requirements October 2003 o Support A Simple Default Communication Profile On The 'Console' o Support Separate Management Plane IP Interfaces o No Forwarding Between Management Plane And Other Interfaces o Provide Separate Resources For The Management Plane A.1.1.4 Configuration Requirements CLI Provides Access to All Configuration and Management Functions CLI Uses Existing Authentication Mechanisms CLI Supports Scripting of Configuration CLI Supports Management Over 'Slow' Links Support Software Installation Support Remote Configuration Backup Support Remote Configuration Restore Support Human-Readable Configuration File A.1.1.5 IP Stack Requirements o Comply With Relevant IETF RFCs on All Protocols Implemented o Ability to Identify All Listening Services o Ability to Disable Any and All Services o Listening Services Should Be Off By Default o Ability to Control Service Bindings for Listening Services o Ability to Control Service Source Address o Support Automatic Anti-spoofing for Single-Homed Networks o Directed Broadcasts Disabled by Default Jones, Editor Expires April 24, 2004 [Page 50] Internet-Draft Operational Security Requirements October 2003 A.1.1.6 Basic Filtering Capabilities o Ability to Filter Traffic o Ability to Filter Traffic TO the Device o Ability to Filter Updates o Ability to Specify Filter Actions o Ability to Log Filter Actions A.1.1.7 Packet Filtering Criteria o Ability to Filter on Protocols o Ability to Filter on Addresses o Ability to Filter on Any Protocol Header Fields o Ability to Filter Inbound and Outbound A.1.1.8 Packet Filtering Counter Requirements o Packet Filtering Counter Requirements o Ability to Display Filter Counters o Ability to Display Filter Counters per Rule o Ability to Display Filter Counters per Filter Application o Ability to Reset Filter Counters o Filter Counters Must Be Accurate A.1.1.9 Other Packet Filtering Requirements o Filter, Counters, and Filter Log Must Have Minimal Performance Impact A.1.1.10 Event Logging Requirements o Logging Facility Conforms to Open Standards Jones, Editor Expires April 24, 2004 [Page 51] Internet-Draft Operational Security Requirements October 2003 o Ability to Log to Remote Server o Ability to Log Locally o Ability to Maintain Accurate System Time o Logs Must Be Timestamped o Logs Contain Untranslated Addresses A.1.1.11 Authentication, Authorization, and Accounting (AAA) Requirements o Authenticate All User Access o Support Authentication of Individual Users o Support Simultaneous Connections o Ability to Disable All Local Accounts o Support Centralized User Authentication Methods o Support Local User Authentication Method o Support Configuration of Order of Authentication Methods o No Unencrypted Transmission of Reusable Plain-text Passwords o Ability to Define Privilege Levels o Ability to Assign Privilege Levels to Users o Default Privilege Level Must Be Read Only o Change in Privilege Levels Requires Re-Authentication o Support Recovery Of Privileged Access o Accounting Records A.1.2 Documentation Requirements o Document Listening Services o Identify Origin of IP Stack Jones, Editor Expires April 24, 2004 [Page 52] Internet-Draft Operational Security Requirements October 2003 o Identify Origin of Operating System A.1.3 Assurance Requirements o Comply With Relevant IETF RFCs on All Protocols Implemented o Identify Origin of IP Stack o Identify Origin of Operating System A.2 Layer 3 Network Core Profile This section builds on the minimal requirements listed in A.1 and adds more stringent security functionality specific to layer 3 devices which are part of the network core. The network core devices need to be as free as possible from features which affect high-speed packet forwarding. A core device is defined as a device that makes up the network infrastructure but does not connect directly to customers or peers. This would include backbone core routers. A.2.1 Functional Requirements A.2.1.1 IP Stack Requirements A.3 Layer 3 Network Edge Profile This section builds on the minimal requirements listed in A.1 and adds more stringent security functionality specific to layer 3 devices which are part of the network edge. The network edge is typically where much of the filtering and traffic control policies are implemented. An edge device is defined as a device that makes up the network infrastructure and connects directly to customers or peers. This would include routers connected to peering points, switches connecting customer hosts, etc. A.3.1 Functional Requirements A.3.1.1 IP Stack Requirements o Support Automatic Anti-spoofing for Single-Homed Networks Jones, Editor Expires April 24, 2004 [Page 53] Internet-Draft Operational Security Requirements October 2003 A.3.1.2 Rate Limiting Requirements o Support Rate Limiting o Support Rate Limiting Based on State A.3.1.3 Basic Filtering Capabilities o Ability to Filter Traffic THROUGH the Device Jones, Editor Expires April 24, 2004 [Page 54] Internet-Draft Operational Security Requirements October 2003 Appendix B. Acknowledgments This document grew out of an internal security requirements document used by UUNET for testing devices that were being proposed for connection to the backbone. The editor gratefully acknowledges the contributions of: o Greg Sayadian, author of a predecessor of this document. o Eric Brandwine, a major source of ideas/critiques. o The MITRE Corporation for supporting continued development of this document. NOTE: The editor's affiliation with The MITRE Corporation is provided for identification purposes only, and is not intended to convey or imply MITRE's concurrence with, or support for, the positions, opinions or viewpoints expressed by the editor. o UUNET's entire network security team (past and present): Jared Allison, Eric Brandwine, Clarissa Cook, Dave Garn, Tae Kim, Kent King, Neil Kirr, Mark Krause, Michael Lamoureux, Maureen Lee, Todd MacDermid, Chris Morrow, Alan Pitts, Greg Sayadian, Bruce Snow, Robert Stone, Anne Williams, Pete White. o Others who have provided significant feedback at various stages of the life of this document are: Ran Atkinson, Fred Baker, Steve Bellovin, Michael H. Behringer, Matt Bishop, Scott Blake, Randy Bush, Steven Christey, Owen Delong, Sean Donelan, Robert Elmore, Barry Greene, Dan Hollis, Merike Kaeo, John Kristoff, Chris Liljenstolpe, James W. Laferriere, Jared Mauch, Alan Paller, Rob Pickering, Gregg Schudel, Don Smith, Rodney Thayer, David Walters, Joel N. Weber II, Anthony Williams, Neal Ziring o Madge B. Harrison, technical writing review. o This listing is intended to acknowledge contributions, not to imply that the individual or organizations approve the content of this document. o Apologies to those who commented on/contributed to the document and were not listed...contact the editor to be credited in future versions Version: $Id: draft-jones-opsec-01.cpp,v 1.4 2003/10/13 11:39:26 george Exp $ Jones, Editor Expires April 24, 2004 [Page 55] Internet-Draft Operational Security Requirements October 2003 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. Full Copyright Statement Copyright (C) The Internet Society (2003). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assignees. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION Jones, Editor Expires April 24, 2004 [Page 56] Internet-Draft Operational Security Requirements October 2003 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Jones, Editor Expires April 24, 2004 [Page 57]