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

(MIB) information. Although the IETF has defined a great many standard MIB definitions,
vendors often implement these MIBs in idiosyncratic and nonstandard ways. The net result is
that the greater the diversity of deployed devices within a deployment, the harder it is to identify
common MIB subsets that can be used to manage devices in a consistent way—and the less
useful the total management system becomes. To correct this, vendors have built management
systems 10 that operate at a higher level of abstraction. Such approaches overcome these
limitations for the products that they support by creating localized clients that address the
administrative differences between vendor products and present these differences in a
regularized (abstracted) manner. Unfortunately, due to the cost of creating the clients, only the
more commonly deployed systems are supported by these systems in general. Consequently,
there is no single management system today that universally supports all IP products.
IP networks are historically managed using the IETF’s SNMP. The first two versions of SNMP
(SNMPv1, SNMPv2) do not have security provisions. While SNMPv3 does have well-defined
security capabilities, helpful functions for enabling SNMP key management within multivendor
environments are optional and, therefore, irregularly supported by the various vendors. The net
result is that SNMPv3 key management is questionable when deployed in large, multivendor
environments, debatably making SNMPv3 among the least secure of the major IETF-defined
protocols for those environments. It is also possible that SNMPv3 in large, multivendor
environments may be among the more vulnerable elements to attack within those deployments—
a distinctly undesirable situation for a protocol that is used to remotely configure and manage
network devices.
The following sections (4.6.1 to 4.6.5) identify historic weaknesses in SNMPv3 security. These
sections are listed in order of increasing importance. The IETF is currently in the process of
enhancing SNMPv3 security within the Integrated Security Model for SNMP (ISMS) working
group to correct many of these problems. 11
4.6.1 The SNMP has no Provisions for Two-Factored Authentication.
Many deployments require their system and network administrators to undergo two factored
authentications to increase the difficulty of hostile attackers successfully impersonating these
important functions. SNMPv3 has no provisions to authenticate based on PKI, password,
biometrics, or almost anything else. SNMPv3 authentication is solely based on the user’s
symmetric authentication key. Therefore, the protocol has no provisions for supporting two
factored authentication.
4.6.2 The SNMP Symmetric Keys may be Assembled From Passwords.
The symmetric keys that are used to authenticate and provide privacy for SNMP
communications may be independently established for each user or they may be algorithmically
constructed from the user’s password. Although the former technique results in significantly
better security, the latter is frequently used because it is the only commonly deployed
10 e.g., HP OpenView; see http://www.managementsoftware.hp.com/
11 See http://www.ietf.org/html.charters/isms-charter.html
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