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

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that is indirectly connected to one’s network is theoretically able to access one’s network). This is in direct contrast with all approaches, which create structures that logically belong to the same larger network system. Unless mitigated by network partitions (see sections 5.4.1 and 5.4.2), the approaches operate in network systems that are logically connected together. The risks are described in section 4.1. By contrast, multilevel networks create protected network systems. Specifically, RED users cannot access BLACK network resources or vice-versa. By so doing, the users that comprise a given network within the multilevel network system are solely the users within that specific network system. Thus, they have a controlled network population within a controlled network system. By contrast, the users that comprise a single level network system are the cumulative users that can access any network within that system. In the case of the Internet, that would be more than a billion people. 5.5 AIRPLANE ROUTING AND AUTONOMOUS SYSTEMS. The AS defines the administrative boundaries of IP systems (see section 5.3). Entities within an AS share common network policies (e.g., QoS, security). They also share common network administrative systems. While military aircraft often belong within a common AS with the other military aircraft with which they are associated (e.g., a squadron), and possibly with the military ground stations that support them, civilian aircraft usually belong to a different AS than the ground systems that support them. This is because civilian aircraft are usually either privately owned or owned by a corporation. In either case, the aircraft owners usually do not belong to the same corporation or agency as the ground stations that support them. While aircraft within the same corporate fleet may be organized into a common AS with other aircraft from that same fleet, this is not done in general because it would cause their intrafleet communications to be significantly different than their interfleet communications. Creating such dissimilar air-to-air relationships adds needless complexity to the entire system and may cause significant problems if not done correctly. The previous paragraph should be readily apparent when aircraft are considered in terms of the IP networking concepts presented in section 5.3. Unfortunately, these IP topology hierarchy relationships permeate airborne network communications in subtle ways. The purpose of this section is to explain the pervasive nature of these concepts upon airborne networking and, by so doing, indicate some of the inherent technical challenges with designing viable airborne network systems (e.g., section 8). The majority of this section is concerned with the routing implications of each airplane being its own AS. However, there are also IP addressing issues that derive from that association. With the advent of CIDR addressing, IP routing systems have increasingly relied on address aggregation to enhance scalability. CIDR has changed IP address semantics by embedding Internet topology information into the address prefix. This information identifies the specific ISP, which that entity uses to connect to the Internet. By so doing, address aggregation is enhanced for the BGP peering relationships between ASs, significantly improving Internet scalability. A side affect of this is that the IP addresses that airplanes adopt contain implicit IP network topology semantics, directly associating that airplane with a specific ISP. This may not be an issue if the worldwide airspace functions as a single ISP. However, a more likely scenario is that the airspace will be segregated into identifiable nationally or regionally controlled 62
deployments. Regional flights that are localized within one of these boundaries would not be affected by this coupling. However, issues occur when aircraft cross between regions during flight since the airplane’s original addresses were associated with their departure ISP. If they maintain those addresses during flight, they will reduce the aggregation and scaling and increase the overhead for the new ISP. There have been many proposed solutions to this problem. • Re-addressing the airplane to the new ISP’s address space. • Assigning multiple IPv6 addresses to every airplane node, each associated with a different ISP. • Assigning the airplane’s IP addresses from private address spaces and then using a NAT to switch between ISPs. • Use of provider independent IP addresses within aircraft. Note: Blocks of the IP address space are not associated with any ISP. Some of the largest corporations and entities (governments) intend to use these addresses so that they would not have any dependencies upon an ISP. This study does not seek to suggest a specific solution to this problem. Rather, it emphasizes that IP addressing is a very significant architectural issue that directly affects connecting aircraft to IP networks. Specifically, both aircraft and the NAS need to operate within a consistent worldwide airborne IP addressing context if civilian aircraft are to cleanly communicate using IP networks. Another significant issue is that the protocols within the IP family were designed for stable network environments having near 100% network availability. 16 Until recently, IP connectivity was primarily accomplished by means of wired media. Wireless media was primarily restricted to environments that were heavily engineered to operate within tight constraints that resembled wire line media environments (from the perspective of the IPs they supported, e.g., wireless LANs, cellular networks). As IP is beginning to be deployed within highly mobile wireless environments (e.g., MANET networks), IPs are encountering environments that significantly differ from their design assumptions. Specifically, the combination of high mobility with wireless media often result in high-signal intermittence rates, and correspondingly diminished network availability rates, for the communicating systems. This signal intermittence may be caused by signal interference from foliage, landforms, buildings, weather, particulate matter (e.g., sandstorms), hostile jamming, signal attenuation, and other factors such aircraft pitch, roll, and yaw introducing signal blockage due to relative antenna placement. IPs in general, and IP routing protocols in particular (both IGP and EGP), react to signal intermittence within their underlying media by greatly exacerbated protocol overheads. These overheads manifest themselves for IP routing protocols both in terms of network capacity consumption as well as in lengthened convergence times. IP routing protocols fail at certain signal intermittence rates. 16 Network availability means that the network services are present and accessible. The concept of availability is distinct from the concept of reliability. For example, a network can be available (i.e., be present) but unreliable (e.g., packets can arrive with jitter, arrive in the incorrect order, or be lost). 63
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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
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LIST OF ACRONYMS AND ABBREVIATIONS
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PBN PC PE PEP PFS PIB PIM-DM PIM-SM
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This report states that the primary
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1. INTRODUCTION. This is the final
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protocol (IP)-based communications.
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of linking aircraft-resident system
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Industry and governments are extrem
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2.1 NOTIONAL NETWORKED AIRCRAFT ARC
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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 and 62: mechanism to overcome the key distr
Page 63 and 64: Deployments that need to support mu
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: via that same IP address. Specifica
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
Page 113 and 114: employed in security-critical appli
Page 115 and 116: concept, which is needed to create
Page 117 and 118: 4. Learn from past mistakes. Poor d
Page 119 and 120: exemplar airborne network architect
Page 121 and 122: • Requirement 8: Biba Integrity M
Page 123 and 124: Figure 31 shows how the recommended
Page 125 and 126: to-live (TTL) field in the IP heade
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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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