Local Area Networks (LANs) in Aircraft - FTP Directory Listing - FAA

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4.6.5 The SNMP Currently Lacks Demonstrably Viable Session Keys. Frequently changing privacy keys are very important for reducing the amount of ciphertext that is available for cryptanalysis. Because SNMP is built upon the UDP protocol rather than TCP, sessions are an abstraction and viable session keys are a challenge to create due to unpredictable request/response relationships. For this reason, the SNMPv3 privacy keys do not operate as session keys. Rather, they frequently have indefinitely long lifetimes, thereby permitting the accumulation of a substantial body of ciphertext over time. The attacker’s ability to gather large amounts of ciphertext may potentially assist in the breaking of these keys. 4.7 MIXING DIFFERENT COMMUNICATION PROTOCOL SYSTEMS. The NAS currently supports protocols belonging to several different protocol families (e.g., the ATN uses the OSI protocol). Private industry and governments repeatedly confront network and security issues related to the translation mechanisms used to get different protocol families to interoperate together. This section discusses relevant issues that need to be considered whenever diverse protocol systems are integrated together. Protocol families is a generic term to refer to distinct protocol systems. The word families reflects the fact that some protocol systems are comprised of multiple orchestrated protocols that cooperate together to form a common system. Figure 11 identifies the two best known examples of protocol systems: OSI and TCP/IP. IP Layer Figure 11. Comparison Between the OSI and TCP/IP Protocol Stacks 46
Deployments that need to support multiple protocol families usually identify a target protocol system and target infrastructure for the deployment to standardize upon. That target system becomes the network core and the other protocol systems “hang off” of that core. Almost without exception, the target protocol is the IP family, which is also known as TCP/IP. The nontarget protocol deployments are generically referred to as being legacy systems. To communicate with IP systems, legacy protocol systems either must be gatewayed into the core target system via protocol translators or converted over time to become part of the target system. For example, Bob Stephens [48] describes a possible approach where the NAS’ ATN protocol and infrastructure can be modified to replace their current OSI connectionless network protocol (CLNP) protocol by IPv6, 12 thereby making ATN become an IP protocol system. 13 ATN is currently an OSI protocol system. The OSI Reference Model defines the high-level unifying networking constructs that guided the creation of the OSI protocols. The OSI protocol deployments are divided into two major protocol variants: • One major variant uses a connection-oriented network service (CONS) layer protocol and a less complicated transport layer protocol (TP) variant (i.e., CONS/TP0). This variant is patterned after historic X.25 protocol systems. • The other major OSI variant that existed in the early 1990s uses a CLNP and a morecomplicated TP variant (i.e., CLNP/TP4). This system is closely patterned after TCP/IP, whose definition preceded it by about a decade. This is the OSI variant that was selected for ATN. The right-hand side of figure 11 shows the TCP/IP family protocol stack. The middle material between the two stack charts in figure 11 is an elaboration of the distinct sublayers defined by OSI for their data link and network layers. One should observe that although the IP Family’s IP Layer is often referred to as being TCP/IP’s network layer, it primarily corresponds to OSI Layer 3c (i.e., OSI’s internetwork sublayer of the network layer). This nit is being explicitly mentioned to introduce a very important point: Even though the OSI CLNP/TP4 variant was closely patterned after TCP/IP, the two protocol systems differ from each other in numerous significant ways. These differences ensure that their protocol deployments cannot naturally communicate together. For example, the state machines that underlie their various protocols are sufficiently different from each other to cause opportunities for the translation gateway devices connecting the two systems to potentially experience problems. 12 13 The IP has two major variants: IPv4 (version 4) is the historic variant that currently populates the majority of the worldwide Internet infrastructure today. IPv6 (version 6) improves upon IPv4’s scaling properties and is gradually replacing IPv4. The IETF has created several transition technologies to ease the migration from IPv4 to IPv6 and to enable networks to simultaneously support both protocols—a topic that is outside of the scope of this document. There is a significant “bug” in reference 48: The presentation contains stack charts that show both OSI’s CLNP and TCP/IP’s protocols being hosted over the data link limited liability corporation (LLC) protocol (i.e., OSI Layer shown in reference 48 could not interoperate with existing IP systems if IP is conveyed over an LLC protocol as 2b—See figure 11). This representation is true for OSI but it is false for IP. Specifically, the IP stacks shown (i.e., IP interoperability requires that a LLC protocol not be present). 47
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DOT/FAA/AR-08/31 Air Traffic Organi
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1. Report No. DOT/FAA/AR-08/31 4. T
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5.4.2 Aircraft as a Node (MIP and M
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11.1 Findings and Recommendations 1
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22 Customer’s L3VPN Protocol Stac
Page 11 and 12: LIST OF ACRONYMS AND ABBREVIATIONS
Page 13 and 14: PBN PC PE PEP PFS PIB PIM-DM PIM-SM
Page 15 and 16: This report states that the primary
Page 17 and 18: 1. INTRODUCTION. This is the final
Page 19 and 20: protocol (IP)-based communications.
Page 21 and 22: of linking aircraft-resident system
Page 23 and 24: Industry and governments are extrem
Page 25 and 26: 2.1 NOTIONAL NETWORKED AIRCRAFT ARC
Page 27 and 28: Other Control Sites Controller ATC
Page 29 and 30: • The security viability of curre
Page 31 and 32: alternative requires that parallel
Page 33 and 34: Aircraft network security is a syst
Page 35 and 36: 4. NETWORK RISKS. This section spec
Page 37 and 38: General Threat Identifiers FAILURE
Page 39 and 40: esources so that the required real-
Page 41 and 42: “With the rise of client-side att
Page 43 and 44: • During an 11-month period (Apri
Page 45 and 46: attempt the theft of passwords. Non
Page 47 and 48: IP networks are organized in terms
Page 49 and 50: either the user or the trusted soft
Page 51 and 52: However, the previous paragraph beg
Page 53 and 54: Table 1. Internet Engineering Task
Page 59 and 60: • Lightweight directory access pr
Page 61: mechanism to overcome the key distr
Page 65 and 66: Today’s Reality: Islands of Commu
Page 67 and 68: Simultaneously, IP addresses are al
Page 69 and 70: in-depth manner. Defense-in-depth m
Page 71 and 72: Protection Detection Reaction / Neu
Page 73 and 74: encrypted and then encapsulated wit
Page 75 and 76: Internet (grouping of autonomous sy
Page 77 and 78: via that same IP address. Specifica
Page 79 and 80: deployments. Regional flights that
Page 81 and 82: neighbor as a next hop after “Hol
Page 83 and 84: Interface Interface Customer Site S
Page 85 and 86: Interface Customer’s Application
Page 87 and 88: Although the vast majority of PBN s
Page 89 and 90: 6. RELATING SAFETY AND SECURITY FOR
Page 91 and 92: 6.1.1 Integrity. As section 4.3 ind
Page 93 and 94: As mentioned in section 4.4, the hi
Page 95 and 96: 6.1.4 Confidentiality. Confidential
Page 97 and 98: their own classification level nor
Page 99 and 100: integrity is not permitted to obser
Page 101 and 102: software has been confirmed as leve
Page 103 and 104: • Both safety and security are co
Page 105 and 106: Device at Safety level X Device at
Page 107 and 108: in a Biba Integrity Model environme
Page 109 and 110: Common Criteria Classes ACM—Confi
Page 111 and 112: (see section 9.10). A secure mechan
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employed in security-critical appli
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concept, which is needed to create
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4. Learn from past mistakes. Poor d
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exemplar airborne network architect
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• Requirement 8: Biba Integrity M
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Figure 31 shows how the recommended
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to-live (TTL) field in the IP heade
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using the traditional dual router i
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mechanism relies upon the controlle
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HAGs are high-assurance devices tha
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8.3.5 Firewall. The firewall needs
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(AJ) or low probability of intercep
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design decisions that need to be de
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9.2 INTEGRATED MODULAR AVIONICS IMP
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9.3 USING PUBLIC IPs. The model and
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alerted the pilots because the fail
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environments. If the certification
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DSS (FIPS 186 [81]). Code signing i
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elationship with other equipment in
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approach is to keep the log informa
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11. SUMMARY. Current civilian aircr
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environments should be extended to
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12. COTS computer systems cannot be
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14. NAS and airborne network archit
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22. If SWAP considerations permit,
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11.2 TOPICS NEEDING FURTHER STUDY.
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9. Lee, Y., Rachlin, E., and Scandu
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32. Loscocco, P., Smalley, S., Muck
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59. Raisinghani, V. and Sridhar, I.
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the following is a pointer to a rel
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Department of Defense Instruction N
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Information Assurance—The Departm
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Threat source—Either (1) intent a
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information found within these data
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(HTTP) traffic (port 80), port scan
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The simple network management proto
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opportunities to crack the hosting
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authorized to perform. 13 However,
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sniffers, log-cleaning scripts, and
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A.3.1 DENIAL OF SERVICE ATTACKS. Th
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• Disclosure: Disclosure of routi
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affected by the signal intermittenc
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A-15. Barbir, A., Murphy, S., and Y
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Survey Question What is the primary
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Survey Question What is the primary
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should be emphasized that there is
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