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Internet Draft
The Definitions of Managed Objects for
the Security Protocols of
the Point-to-Point Protocol
19 April 1993
Frank Kastenholz
FTP Software, Inc
2 High Street
North Andover, Mass 01845 USA
kasten@ftp.com
Status of this Memo
This document is an Internet Draft. 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. Internet Drafts may be updated, replaced, or
obsoleted by other documents at any time. It is not
appropriate to use Internet Drafts as reference material or to
cite them other than as a ``working draft'' or ``work in
progress.'' Please check the 1id-abstracts.txt listing
contained in the internet-drafts Shadow Directories on
nic.ddn.mil, nnsc.nsf.net, nic.nordu.net, ftp.nisc.sri.com, or
munnari.oz.au to learn the current status of any Internet
Draft.
Internet Draft PPP/Security MIB April 1993
This document will be submitted to the Internet Activities
Board as a Proposed Standard. This document defines an
experimental extension to the SNMP MIB. Upon publication as a
Proposed Standard, a new MIB number will be assigned. This is
a working document only, it should neither be cited nor quoted
in any formal document.
This document will expire before 24 Oct. 1993.
Distribution of this document is unlimited.
Please send comments to the author.
1. Abstract
This memo defines an experimental portion of the Management
Information Base (MIB) for use with network management
protocols in TCP/IP-based internets. In particular, it
describes managed objects used for managing the Security
Protocols on subnetwork interfaces using the family of
Point-to-Point Protocols[8, 9, 10, 11, & 12].
This memo does not specify a standard for the Internet
community.
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 2]
Internet Draft PPP/Security MIB April 1993
2. The Network Management Framework
The Internet-standard Network Management Framework consists of
three components. They are:
RFC 1155 which defines the SMI, the mechanisms used for
describing and naming objects for the purpose of
management. RFC 1212 defines a more concise description
mechanism, which is wholly consistent with the SMI.
RFC 1213 defines MIB-II, the core set of managed objects
for the Internet suite of protocols.
RFC 1157 which defines the SNMP, the protocol used for
network access to managed objects.
The Framework permits new objects to be defined for the
purpose of experimentation and evaluation.
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 3]
Internet Draft PPP/Security MIB April 1993
3. Objects
Managed objects are accessed via a virtual information store,
termed the Management Information Base or MIB. Objects in the
MIB are defined using the subset of Abstract Syntax Notation
One (ASN.1) [3] defined in the SMI. In particular, each
object type is named by an OBJECT IDENTIFIER, an
administratively assigned name. The object type together with
an object instance serves to uniquely identify a specific
instantiation of the object. For human convenience, we often
use a textual string, termed the descriptor, to refer to the
object type.
3.1. Format of Definitions
Section 5 contains the specification of all object types
contained in this MIB module. The object types are defined
using the conventions defined in the SMI, as amended by the
extensions specified in [5,6].
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 4]
Internet Draft PPP/Security MIB April 1993
4. Overview
4.1. Object Selection Criteria
To be consistent with IAB directives and good engineering
practice, an explicit attempt was made to keep this MIB as
simple as possible. This was accomplished by applying the
following criteria to objects proposed for inclusion:
(1) Require objects be essential for either fault or
configuration management. In particular, objects for
which the sole purpose was to debug implementations were
explicitly excluded from the MIB.
(2) Consider evidence of current use and/or utility.
(3) Limit the total number of objects.
(4) Exclude objects which are simply derivable from others in
this or other MIBs.
4.2. Structure of the PPP
This section describes the basic model of PPP used in
developing the PPP MIB. This information should be useful to
the implementor in understanding some of the basic design
decisions of the MIB.
The PPP is not one single protocol but a large family of
protocols. Each of these is, in itself, a fairly complex
protocol. The PPP protocols may be divided into three rough
categories:
Control Protocols
The Control Protocols are used to control the operation
of the PPP. The Control Protocols include the Link
Control Protocol (LCP), the Password Authentication
Protocol (PAP), the Link Quality Report (LQR), and the
Challenge Handshake Authentication Protocol (CHAP).
Network Protocols
The Network Protocols are used to move the network
traffic over the PPP interface. A Network Protocol
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 5]
Internet Draft PPP/Security MIB April 1993
encapsulates the datagrams of a specific higher-layer
protocol that is using the PPP as a data link. Note that
within the context of PPP, the term "Network Protocol"
does not imply an OSI Layer-3 protocol; for instance,
there is a Bridging network protocol.
Network Control Protocols (NCPs)
The NCPs are used to control the operation of the Network
Protocols. Generally, each Network Protocol has its own
Network Control Protocol; thus, the IP Network Protocol
has its IP Control Protocol, the Bridging Network
Protocol has its Bridging Network Control Protocol and so
on.
This document specifies the objects used in managing one of
these protocols, namely the PPP Authentication Protocols.
4.3. MIB Groups
Objects in this MIB are arranged into several MIB groups.
Each group is organized as a set of related objects.
These groups are the basic unit of conformance: if the
semantics of a group are applicable to an implementation then
all objects in the group must be implemented.
The PPP MIB is organized into several MIB Groups, including,
but not limited to, the following groups:
o The PPP Link Group
o The PPP LQR Group
o The PPP LQR Extensions Group
o The PPP IP Group
o The PPP Bridge Group
o The PPP Security Group
This document specifies the following group:
PPP Security Group
The PPP Security Group contains all configuration and
control variables that apply to PPP security.
Implementation of this group is optional. Implementation
is optional since the variables in this group provide
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 6]
Internet Draft PPP/Security MIB April 1993
configuration and control for the PPP Security functions.
Thus, these variables should be protected by SNMPv2
security. If an agent does not support SNMPv2 with
privacy it is strongly advised that this group not be
implemented. See the section on "Security
Considerations" at the end of this document.
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 7]
Internet Draft PPP/Security MIB April 1993
5. Definitions
PPP-SEC-MIB DEFINITIONS ::= BEGIN
IMPORTS
experimental, Counter
FROM RFC1155-SMI
OBJECT-TYPE
FROM RFC-1212
ppp
FROM PPP-LCP-MIB;
pppSecurity OBJECT IDENTIFIER ::= { ppp 2 }
pppSecurityProtocols OBJECT IDENTIFIER ::= { pppSecurity 1 }
-- The following uniquely identify the various protocols
-- used by PPP security. These OBJECT IDENTIFIERS are
-- used in the pppSecurityConfigProtocol and
-- pppSecuritySecretsProtocol objects to identify to which
-- protocols the table entries apply.
pppSecurityPapProtocol OBJECT IDENTIFIER ::=
{ pppSecurityProtocols 1 }
pppSecurityChapMD5Protocol OBJECT IDENTIFIER ::=
{ pppSecurityProtocols 2 }
-- PPP Security Group
-- Implementation of this group is optional.
-- This table allows the network manager to configure
-- which security protocols are to be used on which
-- link and in what order of preference each is to be tried
pppSecurityConfigTable OBJECT-TYPE
SYNTAX SEQUENCE OF PppSecurityConfigEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"Table containing the configuration and
preference parameters for PPP Security."
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 8]
Internet Draft PPP/Security MIB April 1993
::= { pppSecurity 2 }
pppSecurityConfigEntry OBJECT-TYPE
SYNTAX PppSecurityConfigEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"Security configuration information for a
particular PPP link."
INDEX { pppSecurityConfigLink,
pppSecurityConfigPreference }
::= { pppSecurityConfigTable 1 }
PppSecurityConfigEntry ::= SEQUENCE {
pppSecurityConfigLink
INTEGER,
pppSecurityConfigPreference
INTEGER,
pppSecurityConfigProtocol
OBJECT IDENTIFIER,
pppSecurityStatus
INTEGER
}
pppSecurityConfigLink OBJECT-TYPE
SYNTAX INTEGER(0..2147483648)
ACCESS read-write
STATUS mandatory
DESCRIPTION
"The value of ifIndex that identifies the entry
in the interface table that is associated with
the local PPP entity's link for which this
particular security algorithm shall be
attempted. A value of 0 indicates the default
algorithm - i.e., this entry applies to all
links for which explicit entries in the table
do not exist."
::= { pppSecurityConfigEntry 1 }
pppSecurityConfigPreference OBJECT-TYPE
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 9]
Internet Draft PPP/Security MIB April 1993
SYNTAX INTEGER(0..2147483648)
ACCESS read-write
STATUS mandatory
DESCRIPTION
"The relative preference of the security
protocol identified by
pppSecurityConfigProtocol. Security protocols
with lower values of
pppSecurityConfigPreference are tried before
protocols with higher values of
pppSecurityConfigPreference."
::= { pppSecurityConfigEntry 2 }
pppSecurityConfigProtocol OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
ACCESS read-write
STATUS mandatory
DESCRIPTION
"Identifies the security protocol to be
attempted on the link identified by
pppSecurityConfigLink at the preference level
identified by pppSecurityConfigPreference. "
::= { pppSecurityConfigEntry 3 }
pppSecurityConfigStatus OBJECT-TYPE
SYNTAX INTEGER {
invalid(1),
valid(2)
}
ACCESS read-write
STATUS mandatory
DESCRIPTION
"Setting this object to the value invalid(1)
has the effect of invalidating the
corresponding entry in the
pppSecurityConfigTable. It is an
implementation-specific matter as to whether
the agent removes an invalidated entry from the
table. Accordingly, management stations must
be prepared to receive tabular information from
agents that corresponds to entries not
currently in use. Proper interpretation of
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 10]
Internet Draft PPP/Security MIB April 1993
such entries requires examination of the
relevant pppSecurityConfigStatus object."
DEFVAL { valid }
::= { pppSecurityConfigEntry 4 }
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 11]
Internet Draft PPP/Security MIB April 1993
-- This table contains all of the ID/Secret pair information.
pppSecuritySecretsTable OBJECT-TYPE
SYNTAX SEQUENCE OF PppSecuritySecretsEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"Table containing the identities and secrets
used by the PPP authentication protocols. As
this table contains secret information, it is
expected that access to this table be limited
to those SNMP Party-Pairs for which a privacy
protocol is in use for all SNMP messages that
the parties exchange. This table contains both
the ID and secret pair(s) that the local PPP
entity will advertise to the remote entity and
the pair(s) that the local entity will expect
from the remote entity. This table allows for
multiple id/secret password pairs to be
specified for a particular link by using the
pppSecuritySecretsIdIndex object."
::= { pppSecurity 3 }
pppSecuritySecretsEntry OBJECT-TYPE
SYNTAX PppSecuritySecretsEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"Secret information."
INDEX { pppSecuritySecretsLink,
pppSecuritySecretsIdIndex }
::= { pppSecuritySecretsTable 1 }
PppSecuritySecretEntry ::= SEQUENCE {
pppSecuritySecretsLink
INTEGER,
pppSecuritySecretsIdIndex
INTEGER,
pppSecuritySecretsDirection
INTEGER,
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 12]
Internet Draft PPP/Security MIB April 1993
pppSecuritySecretsProtocol
OBJECT IDENTIFIER,
pppSecuritySecretsIdentity
OCTET STRING,
pppSecuritySecretsSecret
OCTET STRING,
pppSecuritySecretsStatus
INTEGER
}
pppSecuritySecretsLink OBJECT-TYPE
SYNTAX INTEGER(0..2147483648)
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The link to which this ID/Secret pair applies.
By convention, if the value of this object is 0
then the ID/Secret pair applies to all links."
::= { pppSecuritySecretsEntry 1 }
pppSecuritySecretsIdIndex OBJECT-TYPE
SYNTAX INTEGER(0..2147483648)
ACCESS read-only
STATUS mandatory
DESCRIPTION
"A unique value for each ID/Secret pair that
has been defined for use on this link. This
allows multiple ID/Secret pairs to be defined
for each link. How the local entity selects
which pair to use is a local implementation
decision."
::= { pppSecuritySecretsEntry 2 }
pppSecuritySecretsDirection OBJECT-TYPE
SYNTAX INTEGER {
local-to-remote(1),
remote-to-local(2)
}
ACCESS read-write
STATUS mandatory
DESCRIPTION
"This object defines the direction in which a
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 13]
Internet Draft PPP/Security MIB April 1993
particular ID/Secret pair is valid. If this
object is local-to-remote then the local PPP
entity will use the ID/Secret pair when
attempting to authenticate the local PPP entity
to the remote PPP entity. If this object is
remote-to-local then the local PPP entity will
expect the ID/Secret pair to be used by the
remote PPP entity when the remote PPP entity
attempts to authenticate itself to the local
PPP entity."
::= { pppSecuritySecretsEntry 3 }
pppSecuritySecretsProtocol OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
ACCESS read-write
STATUS mandatory
DESCRIPTION
"The security protocol (e.g. CHAP or PAP) to
which this ID/Secret pair applies."
::= { pppSecuritySecretsEntry 4 }
pppSecuritySecretsIdentity OBJECT-TYPE
SYNTAX OCTET STRING (SIZE(0..255))
ACCESS read-write
STATUS mandatory
DESCRIPTION
"The Identity of the ID/Secret pair. The
actual format, semantics, and use of
pppSecuritySecretsIdentity depends on the
actual security protocol used. For example, if
pppSecuritySecretsProtocol is
pppSecurityPapProtocol then this object will
contain a PAP Peer-ID. If
pppSecuritySecretsProtocol is
pppSecurityChapMD5Protocol then this object
would contain the CHAP NAME parameter."
::= { pppSecuritySecretsEntry 5 }
pppSecuritySecretsSecret OBJECT-TYPE
SYNTAX OCTET STRING (SIZE(0..255))
ACCESS read-write
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 14]
Internet Draft PPP/Security MIB April 1993
STATUS mandatory
DESCRIPTION
"The secret of the ID/Secret pair. The actual
format, semantics, and use of
pppSecuritySecretsSecret depends on the actual
security protocol used. For example, if
pppSecuritySecretsProtocol is
pppSecurityPapProtocol then this object will
contain a PAP Password. If
pppSecuritySecretsProtocol is
pppSecurityChapMD5Protocol then this object
would contain the CHAP MD5 Secret."
::= { pppSecuritySecretsEntry 6 }
pppSecuritySecretsStatus OBJECT-TYPE
SYNTAX INTEGER {
invalid(1),
valid(2)
}
ACCESS read-write
STATUS mandatory
DESCRIPTION
"Setting this object to the value invalid(1)
has the effect of invalidating the
corresponding entry in the
pppSecuritySecretsTable. It is an
implementation-specific matter as to whether
the agent removes an invalidated entry from the
table. Accordingly, management stations must
be prepared to receive tabular information from
agents that corresponds to entries not
currently in use. Proper interpretation of
such entries requires examination of the
relevant pppSecuritySecretsStatus object."
DEFVAL { valid }
::= { pppSecuritySecretsEntry 7 }
END
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 15]
Internet Draft PPP/Security MIB April 1993
6. Acknowledgements
This document was produced by the PPP working group. In
addition to the working group, the author wishes to thank the
following individuals for their comments and contributions:
Bill Simpson -- Daydreamer
Glenn McGregor -- Merit
Jesse Walker -- DEC
Chris Gunner -- DEC
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 16]
Internet Draft PPP/Security MIB April 1993
7. Security Considerations
The PPP MIB affords the network operator the ability to
configure and control the PPP links of a particular system,
including the PPP authentication protocols. This represents a
security risk.
These risks are addressed in the following manners:
(1) All variables which represent a significant security risk
are placed in separate, optional, MIB Groups. As the MIB
Group is the quantum of implementation within a MIB, the
implementor of the MIB may elect not to implement these
groups.
(2) The implementor may choose to implement the variables
which present a security risk so that they may not be
written, i.e., the variables are READ-ONLY. This method
still presents a security risk, and is not recommended,
in that the variables, specifically the PPP
Authentication Protocols' variables, may be easily read.
(3) Using SNMPv2, the operator can place the variables into
MIB views which are protected in that the parties which
have access to those MIB views use authentication and
privacy protocols, or the operator may elect to make
these views not accessible to any party. In order to
facilitate this placement, all security-related variables
are placed in separate MIB Tables. This eases the
identification of the necessary MIB View Subtree.
(4) The PPP Security Protocols MIB (this document) contains
several objects which are very sensitive from a security
point of view.
Specifically, this MIB contains objects that define the
PPP Peer Identities (which can be viewed as "userids")
and the secrets used to authenticate those Peer
Identities (similar to a "password" for the "userid").
Also, this MIB contains variables which would allow a
network manager to control the operation of the security
features of PPP. An intruder could disable PPP security
if these variables were not properly protected.
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 17]
Internet Draft PPP/Security MIB April 1993
Thus, in order to preserve the integrity, security and
privacy of the PPP security features, an implementation
will allow access to this MIB only via SNMPv2 and then
only for parties which are privacy enhanced. Other
access modes, e.g., SNMPv1 or SNMPv2 without privacy-
enhancement, are very dangerous and the security of the
PPP service may be compromised.
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 18]
Internet Draft PPP/Security MIB April 1993
8. References
[1] M.T. Rose and K. McCloghrie, Structure and Identification
of Management Information for TCP/IP-based internets,
Internet Working Group Request for Comments 1155.
Network Information Center, SRI International, Menlo
Park, California, (May, 1990).
[2] K. McCloghrie and M.T. Rose, Management Information Base
for Network Management of TCP/IP-based internets - MIB-2,
Internet Working Group Request for Comments 1213.
Network Information Center, SRI International, Menlo
Park, California, (March, 1991).
[3] Information processing systems - Open Systems
Interconnection - Specification of Abstract Syntax
Notation One (ASN.1), International Organization for
Standardization. International Standard 8824, (December,
1987).
[4] Information processing systems - Open Systems
Interconnection - Specification of Basic Encoding Rules
for Abstract Notation One (ASN.1), International
Organization for Standardization. International Standard
8825, (December, 1987).
[5] Rose, M., and K. McCloghrie, Editors, Concise MIB
Definitions, RFC 1212, Performance Systems International,
Hughes LAN Systems, March 1991.
[6] Rose, M., Editor, A Convention for Defining Traps for use
with the SNMP, RFC 1215, Performance Systems
International, March 1991.
[7] K. McCloghrie, Extensions to the Generic-Interface MIB,
RFC1229, Hughes LAN Systems, May 1991.
[8] W. Simpson, The Point-to-Point Protocol for the
Transmission of Multi-protocol Datagrams over Point-to-
Point Links, RFC 1331, May 1992.
[9] G. McGregor, The PPP Internet Protocol Control Protocol,
RFC 1332, Merit, May 1992.
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 19]
Internet Draft PPP/Security MIB April 1993
[10] F. Baker, Point-to-Point Protocol Extensions for
Bridging, RFC1220, ACC, April 1991.
[11] B. Lloyd, and Simpson, W., PPP Authentication Protocols
RFC1334, October 1992.
[12] W. Simpson, PPP Link Quality Monitoring, RFC 1333, May
1992.
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 20]
Internet Draft PPP/Security MIB April 1993
Table of Contents
Status of this Memo .................................... 1
1 Abstract .............................................. 2
2 The Network Management Framework ...................... 3
3 Objects ............................................... 4
3.1 Format of Definitions ............................... 4
4 Overview .............................................. 5
4.1 Object Selection Criteria ........................... 5
4.2 Structure of the PPP ................................ 5
4.3 MIB Groups .......................................... 6
5 Definitions ........................................... 8
6 Acknowledgements ...................................... 16
7 Security Considerations ............................... 17
8 References ............................................ 19
Frank J. Kastenholz Exp. 24 Oct. 1993 [Page 21]