Application Working Group M. Ansari
INTERNET-DRAFT Sun Microsystems, Inc.
Expires June 2001 L. Howard
PADL Software Pty. Ltd.
B. Joslin [ed.]
Hewlett-Packard Company
November 17, 2000
Intended Category: Informational
A Configuration Schema for LDAP Based
Directory User Agents
<draft-joslin-config-schema-00.txt>
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
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Distribution of this document is unlimited.
Abstract
ABSTRACT
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This document describes a mechanism for global confi-
guration of similar directory user agents. This docu-
ment proposes a schema for configuration of these DUAs
that may be discovered using the Lightweight Directory
Access Protocol [RFC2251]. A set of attribute types and
an objectclass are proposed, along with specific guide-
lines for interpreting them. A significant feature of
the global configuration policy for DUAs, is a mechan-
ism that allows DUAs to re-configure their schema to
that of the end user's environment. This configuration
is achieved through attribute and objectclass mapping.
This document is intended to be a skeleton for future
documents that describe configuration of specific DUA
services.
1. Background & Motivation
The LDAP protocol has brought about a new and nearly ubiquitous
acceptance of the directory server. Many new client applications
(DUAs) are being created that use LDAP directories for many dif-
ferent services. And although the LDAP protocol has eased the
development of these applications, some challenges still exist for
both developers and directory administrators.
The authors of this document are implementors of DUAs described by
RFC 2307 [14]. In developing these agents, we felt there are
several issues that still need to be addressed to ease the deploy-
ment and configuration of a large network of these DUAs.
One of these challenges stems from the lack of a utopian schema. A
utopian schema would be one that every application developer could
agree upon and that would support every application. Unfortunately
today, many DUAs define their own schema (like RFC 2307 vs
Microsoft's Services for Unix [13]) containing similar attributes,
but with different attribute names. This can lead to data redun-
dancy within directory entries and give directory administrators
unwanted challenges, updating schemas and synchronizing data.
So, one goal of this document is to eliminate data redundancy by
having DUAs configure themselves to the schema of the deployed
directory, instead of forcing it's own schema on the directory.
Another goal of this document is to provide the DUA with enough
configuration information so that it can discover how to retrieve
its data in the directory, such as what locations to search in the
directory tree.
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Finally, this document intends to describe a configuration method
for DUAs that can be shared among many DUAs, on various platforms,
providing as such, a configuration profile. The purpose being to
centralize and simplify management of DUAs.
This document is intended to provide the skeleton framework for
future drafts, which will describe the individual implementation
details for the particular services provided by that DUA. The
authors of this draft plan to develop such an document for the Net-
work Information Service DUA, described by RFC 2307 or it's succes-
sor.
We expect that as DUAs take advantage of this configuration scheme,
each DUA will require additional configuration paramenters, not
specified by this draft. Thus, we would expect that new auxiliary
object classes, containing new configuration attributes will be
created, and then joined with the structural class defined by this
draft to create a configuration profile for a particular DUA ser-
vice. And that by joining various auxiliary objectclasses for dif-
ferent DUA services, that configuration of various DUA services can
be controlled by a single configuration profile entry.
2. General Issues
The schema defined by this draft is defined under the "DUA Confi-
guration Schema." This schema is derived from the OID: iso (1)
org (3) dod (6) internet (1) private (4) enterprises (1) Hewlett-
Packard Company (11) directory (1) LDAP-UX Integration Project (3)
DUA Configuration Schema (1). This OID is represented in this
draft by the keystring "DUAConfSchemaOID" (1.3.6.1.4.1.11.1.3.1).
2.1 Terminology
The key words "MUST", "SHOULD", and "MAY" used in this document are
to be interpreted as described in [RFC2119].
2.2 Attributes
The attributes and classes defined in this document are summarized
below.
The following attributes are defined in this document:
preferredServerList
defaultServerList
defaultSearchBase
defaultSearchScope
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authenticationMethod
credentialLevel
serviceSearchDescriptor
attributeMap
objectclassMap
searchTimeLimit
bindTimeLimit
followReferrals
profileTTL
2.3 Object Classes
The following object class is defined in this document:
DUAConfigProfile
2.4 Syntax Definitions
The following syntax definitions are used throughout this draft.
keystring as defined by RFC 2252 [2]
descr as defined by RFC 2252 section 4.1
a as defined by RFC 2252 section 4.1
d as defined by RFC 2252 section 4.1
space as defined by RFC 2252 section 4.1
whsp as defined by RFC 2252 section 4.1
base as defined by RFC 2253 [3]
DistinguishedName as defined by RFC 2253 section 2
RelativeDistinguishedName as defined by RFC 2253 section 2
scope as defined by RFC 2255 [5]
IPv4address as defined by RFC 2396 [9]
hostport as defined by RFC 2396 section 3.2.2
port as defined by RFC 2396 section 3.2.2
ipv6reference as defined by RFC 2732 [10]
host as defined by RFC 2732 section 3
serviceId = keystring
The following additional syntax definitions are defined in this
schema.
2.4.1 serviceSearchSyntax
The serviceSearchSyntax describes a structure used to help DUA ser-
vices discover information in the directory.
( DUAConfSchemaOID.0.8 NAME 'serviceSearchSyntax'
DESC 'DUA service search descriptor list syntax' )
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Values in this syntax are represented by the following:
serviceSearchList = serviceId ":" serviceSearchDesc
*(";" serviceSearchDesc)
serviceSearchDesc = confReferral | searchDescriptor
searchDescriptor = [base] ["?" [scope] ["?" [filter]]]
confReferral = "ref:" DistinguishedName
base = DistinguishedName |
RelativeDistinguishedName ","
filter = 1*filterc
filterc = a | d | "&" | "|" | "!" | "=" | ">" |
"<" | "~" | "(" | ")" | "*" | ":"
If the base or filter contains the ";" (ASCII 0x3B) "?" (ASCII
0x3F) """ (ASCII 0x22) or " escaped (preceded with the " sur-
rounded by quotes (ASCII 0x22.) Refer to RFC 2253, section 4.
If the DN is surrounded by quotes, only the """ character must
be escaped. Any character that is preceded by the " need to
be escaped results in both " itself.
2.4.2 serverListSyntax
The serverListSyntax represents the list of DSAs that will be con-
tacted to retrieve DUA service data.
( DUAConfSchemaOID.0.1 NAME 'serverListSyntax'
DESC 'DSA host address list to be used by a Posix DUA' )
serverList = host *(space [host])
2.4.3 attributeMappingSyntax
The attributeMappingSyntax represents a mapping from an attribute
defined by a DUA to an attribute in an alternative schema used in
the directory.
( DUAConfSchemaOID.0.2 NAME 'attributeMappingSyntax'
DESC 'DUA attribute mapping syntax' )
Values in this syntax are represented by the following:
attributeMap = serviceId ":" origAttribute "="
attributes
origAttribute = attribute
attributes = wattribute *( space wattribute )
wattribute = whsp newAttribute whsp
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newAttribute = descr | "*NULL*"
attribute = descr
Values of the origAttribute depend on the type of application
using the attribute mapping feature.
2.4.4 ObjectClassMappingSyntax
The ObjectClassMappingSyntax represents a mapping from an
objectclass defined by a DUA to an objectclass in an alternative
schema used in the directory.
( DUAConfSchemaOID.0.6 NAME 'ObjectclassMappingSyntax'
DESC 'DUA objectclass mapping syntax' )
Values in this syntax are represented by the following:
objectclassMap = serviceId ":" origObjectclass "="
objectclass
origObjectclass = objectclass
objectclass = keystring
Values of the origObjectclass depend on the type of applica-
tion using the objectclass mapping feature.
2.4.5 authenticationMethodSyntax
The authenticationMethodSyntax represents required authentication
method a DUA MUST use when authenticating to the DUA.
( DUAConfSchemaOID.0.3 NAME 'authenticationMethodSyntax'
DESC 'DUA authentication method hint' )
Values in this syntax are represented by the following:
authMethod = method *(";" method)
method = none | simple | sasl | tls
none = "none"
simple = "simple"
sasl = "sasl/" saslmech [ ":" sasloption ]
sasloption = "auth-conf" | "auth-int"
tls = "tls:" (none | simple | sasl)
saslmech = SASL mechanism name as defined in
RFC 2222, section 3
Note: Although multiple authentication methods may be
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specified in the syntax, at most one of each type is allowed.
2.4.6 credentialLevelSyntax
The credentialLevelSyntax identifies the type of credentials that
should be used when an DUA is authenticating to an LDAP directory.
( DUAConfSchemaOID.0.5 NAME 'credentialLevelSyntax'
DESC 'DUA authentication credential level' )
Values in this syntax are represented by the following:
credentialLevel = level *(space level)
level = self | proxy | anonymous
self = "self"
proxy = "proxy"
anonymous = "anonymous"
Refer to implementation notes in section 5.2 for additional
syntax requirements for the credentialLevel attribute.
2.4.7 scopeSyntax
The scopeSyntax defines the default scope for LDAP searches per-
formed by the DUA.
( DUAConfSchemaOID.0.7 NAME 'scopeSyntax'
DESC 'Default DUA search scope' )
Values in this syntax are represented by the following:
scopeSyntax = "base" | "one" | "sub"
Refer to implementation notes in section 5.2 for additional
syntax requirements for the credentialLevel attribute.
3. Attribute Definitions
This section contains attribute definitions to be used by DUAs when
discovering their configuration.
( DUAConfSchemaOID.1.0 NAME 'defaultServerList'
DESC 'Default LDAP server host address used by a DUA'
EQUALITY caseIgnoreIA5Match
SYNTAX DUAConfSchemaOID.0.1
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SINGLE-VALUE )
( DUAConfSchemaOID.1.1 NAME 'defaultSearchBase'
DESC 'Default LDAP base DN used by a DUA'
EQUALITY distinguishedNameMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.12
SINGLE-VALUE )
( DUAConfSchemaOID.1.2 NAME 'preferredServerList'
DESC 'Preferred LDAP server host addresses to be used by a
DUA'
EQUALITY caseIgnoreIA5Match
SYNTAX DUAConfSchemaOID.0.1
SINGLE-VALUE )
( DUAConfSchemaOID.1.3 NAME 'searchTimeLimit'
DESC 'Maximum time in seconds a DUA should allow for a
search to complete'
EQUALITY integerMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
SINGLE-VALUE )
( DUAConfSchemaOID.1.4 NAME 'bindTimeLimit'
DESC 'Maximum time in seconds a DUA should allow for the
bind operation to complete'
EQUALITY integerMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
SINGLE-VALUE )
( DUAConfSchemaOID.1.5 NAME 'followReferrals'
DESC 'Tells DUA if it should follow referrals
returned by a DSA search result'
EQUALITY caseIgnoreIA5Match
SYNTAX 1.3.6.1.4.1.1466.115.121.1.7
SINGLE-VALUE )
( DUAConfSchemaOID.1.6 NAME 'authenticationMethod'
DESC 'A keystring which identifies the type of
authentication method used to contact the DSA'
EQUALITY caseIgnoreIA5Match
SYNTAX DUAConfSchemaOID.0.3
SINGLE-VALUE )
( DUAConfSchemaOID.1.7 NAME 'profileTTL'
DESC 'Time to live before a client DUA should re-read this
configuration profile'
EQUALITY integerMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
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SINGLE-VALUE )
( DUAConfSchemaOID.1.14 NAME 'serviceSearchDescriptor'
DESC 'LDAP search descriptor list used by Naming-DUA'
EQUALITY caseExactIA5Match
SYNTAX DUAConfSchemaOID.0.8 )
( DUAConfSchemaOID.1.9 NAME 'attributeMap'
DESC 'Attribute mappings used by a Naming-DUA'
EQUALITY caseIgnoreIA5Match
SYNTAX DUAConfSchemaOID.0.2 )
( DUAConfSchemaOID.1.10 NAME 'credentialLevel'
DESC 'Identifies type of credentials a DUA should
use when binding to the LDAP server'
EQUALITY caseIgnoreIA5Match
SYNTAX DUAConfSchemaOID.0.5
SINGLE-VALUE )
( DUAConfSchemaOID.1.11 NAME 'objectclassMap'
DESC 'Objectclass mappings used by a Naming-DUA'
EQUALITY caseIgnoreIA5Match
SYNTAX DUAConfSchemaOID.0.6 )
( DUAConfSchemaOID.1.12 NAME 'defaultSearchScope'
DESC 'Default search scope used by a DUA'
EQUALITY caseIgnoreIA5Match
SYNTAX DUAConfSchemaOID.0.7
SINGLE-VALUE )
4. Class Definition
The objectclass below is constructed from the attributes defined in
3, with the exception of the cn attribute, which is defined in RFC
2256 [8]. cn is used to represent the name of the DUA configura-
tion profile.
( DUAConfSchemaOID.2.3 NAME 'DUAConfigProfile'
SUP top STRUCTURAL
DESC 'Abstraction of a base configuration for a DUA'
MUST ( cn )
MAY ( defaultServerList $ preferredServerList $
defaultSearchBase $ defaultSearchScope $
searchTimeLimit $ bindTimeLimit $
credentialLevel $ authenticationMethod $
followReferrals $ serviceSearchDescriptor $
objectclassMap $ attributeMap $
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profileTTL ) )
5. Implementation Details
5.1.1 Interpreting the preferredServerList attribute
Interpretation:
As described by the syntax, the preferredServerList parameter
is a white-space separated list of server addresses and asso-
ciated port numbers. When the DUA needs to contact a DSA, the
DUA MUST first attempt to contact one of the servers listed in
the preferredServerList attribute. The DUA should contact the
DSA specified by the first server address in the list. If
that DSA is unavailable, the remaining DSAs should be queried
in the order provided until a connection is established with a
DSA. Once a connection with a DSA is established, the DUA
SHOULD NOT attempt to establish a connection with the remain-
ing DSAs.
If the DUA is unable to contact any of the DSAs specified by
the preferredServerList, the defaultServerList attribute
should be examined, as described in 5.1.2. The servers iden-
tified by the preferredServerList MUST be contacted before
attempting to contact any of the servers specified by the
defaultServerList.
Default Value:
The preferredServerList attribute does not have a default
value. Instead a DUA should examine the defaultServerList
attribute.
Other attribute notes:
This attribute is used in conjunction with the defaultServer-
List attribute. Please see section 5.1.2 for additional
implementation notes. Determining how the DUA should query
the DSAs also depends on the additional configuration attri-
butes, credentialLevel, bindTimeLimit, and authentication-
Method. Please review section 5.2 for details on how a Posix
DUA should properly bind to a DSA.
5.1.2 Interpreting the defaultServerList attribute
Interpretation:
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The defaultServerList attribute MUST only be examined if the
preferredServerList attribute is not provided, or the DUA is
unable to establish a connection with one of the DSAs speci-
fied by the preferredServerList.
If more than one address is provided, the DUA may choose to
either accept the order provided, or choose to create its own
order, based on what the DUA determines is the "best" order of
servers to query. For example, the DUA may choose to examine
the server list and choose to query the DSAs in order based on
the "closest" server or the server with the least amount of
"load." Interpretation of the "best" server order is entirely
up to the DUA, and not part of this draft.
Once the order of server addresses is determined, the DUA
should contact the DSA specified by the first server address
in the list. If that DSA is unavailable, the remaining DSAs
should be queried until an available DSA is found or no more
DSAs are available. If a server address or port is invalid,
the DUA should proceed to the next server address as described
just above.
Default Value:
If a defaultServerList attribute is not provided, the DUA
should attempt to contact the same DSA which provided the con-
figuration profile entry itself. The default DSA is contacted
only if the preferredServerList attribute is also not pro-
vided.
Other attribute notes:
This attribute is used in conjunction with the preferredSer-
verList attribute. Please see section 5.1.1 for additional
implementation notes. Determining how the DUA should query
the DSAs also depends on the additional configuration attri-
butes, credentialLevel, bindTimeLimit, and authentication-
Method. Please review section 5.2 for details on how a DUA
should properly contact a DSA.
5.1.3 Interpreting the defaultSearchBase attribute
Interpretation:
When a DUA needs to search the DSA for information, this
attribute provides the "base" for the search. This parameter
can be overridden or appended by the serviceSearchDescriptor
attribute. See section 5.1.6.
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Default Value:
There is no default value for the defaultSearchBase.
Other attribute notes:
This attribute is used in conjunction with the serviceSear-
chDescriptor attribute. See section 5.1.6.
5.1.4 Interpreting the authenticationMethod attribute
Interpretation:
The authenticationMethod attribute defines an ordered list of
LDAP bind methods to be used when attempting to contact a DSA.
Each method MUST be attempted in the order provided by the
attribute, until a successful LDAP bind is performed ("none"
is assumed to always be successful). See section 5.2 for more
information.
none - The DUA does not perform an LDAP bind.
simple - The DUA performs an LDAP simple bind.
sasl - The DUA performs an LDAP SASL bind using the
specified SASL mechanism and options.
tls - The DUA performs an LDAP start_tls operation
followed by the specified bind method (for more
information refer to section 5.1 of RFC 2830).
Default Value:
If the authenticationMethod attribute is not provided, the DUA
may choose to bind to the DSA using any method. However, if
the authenticationMethod is provided, the DUA MUST only use
the methods specified.
Other attribute notes:
Determining how the DUA should bind to the DSAs also depends
on the additional configuration attributes, credentialLevel
and bindTimeLimit. Please review section 5.2 for details on
how to properly bind to a DSA.
5.1.5 Interpreting the credentialLevel attribute
Interpretation:
The credentialLevel attribute defines what type(s) of
credential(s) the DUA should use when contacting the DSA. The
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credentialLevel can contain more than one credential type,
separated by white space.
anonymous - The DUA should not use a credential when binding
to the DSA.
proxy - The DUA should use a known proxy identity when binding
to the DSA. A proxy identity is a specific credential that
was created to represent the DUA. This document does not
define how the proxy user should be created, or how the DUA
should determine what the proxy user's credential is. This
functionality is up to each implementation.
self - When the DUA is acting on behalf of a "real user" the
DUA should attempt to bind to the DSA as that user. The DUA
should map the user's identity to a credential used in the
directory.
If the DUA contains more than one credential type, the DUA
SHOULD use the credential types in the order specified. As
soon as the DUA is able to successfully bind to the DSA, the
DUA should not attempt to bind using the remaining credential
types. If the DUA discovers that the credentials specified
are invalid, it should not attempt further binds using any
additional methods.
Default Value:
If the credentialLevel attribute is not defined, the DUA
should not use a credential when binding to the DSA (also
known as anonymous.)
Other attribute notes:
Determining how the DUA should bind to the DSAs also depends
on the additional configuration attributes, credentialLevel
and bindTimeLimit. Please review section 5.2 for details on
how to properly bind to a DSA.
5.1.6 Interpreting the serviceSearchDescriptor attribute
Interpretation:
The serviceSearchDescriptor attribute defines how and where a
DUA should search for a given service. The serviceSear-
chDescriptor contains a serviceId, followed by one or more
base-scope-filter triples. These base-scope-filter triples
are used to define searches only for the specific service.
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Multiple base-scope-filters allow the DUA to search for data
in multiple locations of the DIT.
In addition to the triples, serviceSearchDescriptor might also
contain the DN of an entry which will contain more servi-
ceSearchDescriptors for the given service.
If the base, as defined in the serviceSearchDescriptor, is
followed by the "," (ASCII 0x2C) character, this base is known
as a relative base (or relative distinguished name.) The DUA
MUST define the search base by appending the relative base
with the defaultSearchBase.
Example:
defaultSearchBase: dc=mycompany,dc=com
serviceSearchDescriptor: email:ou=people,?one;
ou=contractor,?one;
ref:cn=profile,dc=mycompany,dc=com
In this example, the DUA SHOULD search in
"ou=people,dc=mycompany,dc=com" first. The DUA then MAY
search in "ou=contractor,dc=mycompany,dc=com", and finally it
MAY search other locations as specified in
"cn=profile,dc=mycompany,dc=com".
If a DUA is performing a search for a particular service which
has a serviceSearchDescriptor defined, the DUA should set the
base, scope and filter as defined. Each base-scope-filter
triple represents a single LDAP search operation. If multiple
base-scope-filter triples are provided, the DUA should perform
the search requests in the order specified by the serviceSear-
chDescriptor.
Default Values:
If a serviceSearchDescriptor or an element there-of is not
defined for a particular service, the DUA SHOULD create the
base, scope and filter as follows:
base - Same as the defaultSearchBase
scope - Same as the defaultSearchScope
filter - Use defaults as defined by DUAs service.
If the defaultSearchBase is not defined, then the DUAs service
may use its own default.
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Other attribute notes:
If a serviceSearchDescriptor exists for a given service, the
service MUST use at least one base-scope-filter triple in per-
forming searches. It MAY perform multiple searches per ser-
vice if multiple base-scope-filter triples are defined for
that service.
The details of how the "filter" is interpreted by each DUAs
service is defined by each service. This means the filter is
NOT REQUIRED to be a legal LDAP filter [4]. Furthermore,
whether attribute mapping or objectclass mapping applies to
the filter or not should be defined by each service.
It is assumed the serviceID is unique to a given service
within the scope of the DSA.
5.1.7 Interpreting the attributeMap attribute
Interpretation:
A DUA SHOULD perform attribute mapping for all LDAP operations
performed for a service which has an attributeMap entry.
Because attribute mapping is specific to each service within
the DUA, a "serviceId" is required as part of the attributeMap
syntax. Not all DUA services should necessarily perform the
same attribute mapping.
Attribute mapping MUST only be used to map attributes of simi-
lar syntaxes as required by the service supported by the DUA.
However, a DUA is NOT REQUIRED to verify syntaxes of mapped
attributes.
Suppose a DUA is acting on behalf of an email service. By
default the "email" service uses the "mail", "cn" and "sn"
attributes to discover mail addresses. However, the email
service has been deployed in an environment that uses "employ-
eeName". In this case, the attribute "cn" can be mapped to
"employeeName," allowing the DUA to perform searches using the
"employeeName" attribute as part of the search filter, instead
of "cn". This mapping is performed by adding an attributeMap
attribute to the configuration profile entry as follows
(represented in [LDIF]):
attributeMap: email:cn=employeeName
DUAs MAY also map a single attribute to multiple attributes.
When mapping a single attribute to more than one attribute,
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the new syntax or usage of the mapped attribute must be int-
rinsically defined by the DUAs service.
Example:
attributeMap: email:cn=firstName lastName
In this example, the DUA creates the new value by generating
space separated string using the values of the mapped attri-
butes. That might result in: "Bill Myponga"
Default Value:
The DUA MUST NOT remap an attribute unless it is explicitly
defined by an attributeMap attribute.
Other attribute notes:
When an attribute is mapped to the special keystring "*NULL*",
the DUA MUST NOT request that attribute from the DSA, when
performing a search request. If the DUA is also capable of
performing modification on the DSA, the DUA MUST NOT attempt
to modify any attribute which has been mapped to "*NULL*".
It is assumed the serviceID is unique to a given service
within the scope of the DSA.
A DUA SHOULD support attribute mapping. If it does, the fol-
lowing additional rules apply:
1) If an attribute may be mapped to multiple attributes the
DSA MUST define a syntax or usage statement for how the new
attribute value will be evaluated. Furthermore, the resulting
syntax of the combined attributes must be the same as the
attribute being mapped.
2) A DUA MUST support mapping of attributes using the attri-
bute OID. It SHOULD support attribute mapping based on the
attribute name.
3) Naming attribute MAY NOT be mapped using one to many map-
ping.
4) Mapping should only be applied to the target entries being
searched. Attribute mapping should not be applied to parents
of the target entries.
5.1.8 Interpreting the searchTimeLimit attribute
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Interpretation:
The searchTimeLimit attribute defines the maximum time, in
seconds, that a DUA should spend performing a search request
request.
Default Value:
If the searchTimeLimit attribute is not defined or is zero,
the search time limit is not enforced by the DUA.
Other attribute notes:
This timelimit only includes the amount of time required to
perform the LDAP search operation. If other operations are
required, those operations do not need to be considered part
of the search time. See bindTimeLimit for the LDAP bind
operation.
5.1.9 Interpreting the bindTimeLimit attribute
Interpretation:
The bindTimeLimit attribute defines the maximum time, in
seconds, that a DUA should spend performing an LDAP bind
request against each server on the preferredServerList or
defaultServerList.
Default Value:
If the bindTimeLimit attribute is not defined or is zero, the
bind time limit is not enforced by the DUA.
Other attribute notes:
This time limit only includes the amount of time required to
perform the LDAP bind operation. If other operations are
required, those operations do not need to be considered part
of the bind time. See searchTimeLimit for the LDAP search
operation.
5.1.10 Interpreting the followReferrals attribute
Interpretation:
If set to TRUE, the DUA SHOULD follow any referrals if
discovered.
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If set to FALSE, the DUA MUST NOT follow referrals.
Default Value:
If the followReferrals attribute is not set or set to an
invalid value the default value is TRUE.
5.1.11 Interpreting the profileTTL attribute
Interpretation:
The profileTTL attribute defines how often the DUA SHOULD re-
load and reconfigure itself with using the corresponding con-
figuration profile entry. The value is represented in
seconds. Once a DUA reloads the profile entry, it SHOULD re-
configure itself with the new values.
Default Value:
If not specified the DUA MAY use its own reconfiguration pol-
icy.
Other attribute notes:
If the profileTTL value is zero, the DUA SHOULD NOT automati-
cally re-load the configuration profile.
5.1.12 Interpreting the objectclassMap attribute
Interpretation:
A DUA SHOULD perform objectclass mapping for all LDAP opera-
tions performed for a service which has an objectclassMap
entry. Because objectclass mapping is specific to each ser-
vice within the DUA, a "serviceId" is required as part of the
objectclassMap syntax. Not all DUA services should neces-
sarily perform the same objectclass mapping.
Objectclass mapping should be used in conjunction with attri-
bute mapping to map the required schema by the service to an
equivalent schema that is available in the directory.
Suppose a DUA is acting on behalf of an email service. By
default the "email" service uses the "mail", "cn" and "sn"
attributes to discover mail addresses in entries created using
inetorgperson objectclass. However, the email service has
been deployed in an environment that uses entries created
using "employee" objectclass. In this case, the attribute
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"cn" can be mapped to "employeeName", and "inetorgperson" can
be mapped to "employee", allowing the DUA to perform LDAP
operations using the entries which exist in the directory.
This mapping is performed by adding attributeMap and
objectclassMap attributes to the configuration profile entry
as follows (represented in [LDIF]):
attributeMap: email:cn=employeeName
objectclassMap: email:inetorgperson=employee
Default Value:
The DUA MUST NOT remap an objectclass unless it is explicitly
defined by an objectclassMap attribute.
Other attribute notes:
A DUA SHOULD support objectclass mapping. If it does, the DUA
MUST support mapping of objectclasses using the objectclass
OID. It SHOULD support objectclass mapping based on the
objectclass name.
It is assumed the serviceID is unique to a given service
within the scope of the DSA.
5.1.13 Interpreting the defaultSearchScope attribute
Interpretation:
When a DUA needs to search the DSA for information, this
attribute provides the "scope" for the search. This parameter
can be overridden by the serviceSearchDescriptor attribute.
See section 5.1.6.
Default Value:
The default value for the defaultSearchScope is "one",
representing one level search.
5.2 Binding to the Directory Server
The DUA SHOULD use the following algorithm when binding to the
server:
for (host in hostnames) [Note 1]
for (clevel in credentialLevel) {
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if (clevel is anonymous)
return success [Note 2]
for (amethod in authMethod) {
if (amethod is none)
return success [Note 2]
authenticate to host, using amethod and clevel
if (authentication failed with bad credential)
try next clevel
if (authentication passed)
return success
}
}
Note 1: hostnames is the list of server to contact as defined
in 5.1.1 & 5.1.2.
Note 2: In case of anonymous or none, the DUA MAY try contacting
the server to ensure the directory server is available
and responding to requests.
6. Security Considerations
The profile entries MUST be protected against unauthorized modifi-
cation. Since the profile is most useful if its content is avail-
able broadly, it is recommended that the profile entries will be
readable anonymously. However, ultimately each service needs to
consider implications of providing its service configuration as
part of this profile and limit access to the profile entries
accordingly. Additionally, the management of the authentication
credentials for the DUA is outside the scope of this document and
needs to be handled by the DUA.
7. Acknowledgments
There were several additional authors of this document. However we
chose to represent only one author per company in the heading.
From Sun we also would like to acknowledge Roberto Tam for his
design work on Sun's first LDAP name service product and his input
for this draft. From Hewlett-Packard we'd like to acknowledge Dave
Binder for his work architecting Hewlett-Packard's LDAP name ser-
vice product as well as his design guidance on this draft. We'd
also like to acknowledge Grace Lu from HP, for her input and imple-
mentation of HP's configuration profile manager code.
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8. References
[1]
M. Wahl, H. Alvestrand, J. Hodges, R. Morgan, "Authentication
Methods for LDAP", RFC 2828, May 2000
[2]
M. Wahl, A. Coulbeck, T. Howes, S. Kille, "Lightweight Directory
Access Protocol (v3): Attribute Syntax Definitions", RFC 2252,
December 1997.
[3]
M. Wahl, S. Kille, T. Howes, "Lightweight Directory Access Protocol
(v3): UTF-8 String Representation of Distinguished Names", RFC
2253, December 1997.
[4]
T. Howes, "The String Representation of LDAP Search Filters", RFC
2254, December 1997.
[5]
T. Howes, M. Smith, "The LDAP URL Format", RFC 2255, December 1997.
[6]
T. Berners-Lee, L. Masinter, M. McCahill, "Uniform Resource Loca-
tors (URL)", RFC 1738, December 1994.
[7]
J. Meyers, "Simple Authentication and Security Layer [SASL]", RFC
2222, October 1997
[8]
M. Wahl, "A Summary of the X.500(96) User Schema for use with
LDAPv3", RFC 2256, December 1997.
[9]
T. Berners-Lee, R. Fielding, R. Fielding, "Uniform Resource Iden-
tifiers (URI): Generic Syntax", RFC 2396, August 1998.
[10]
R. Hinden, B. Carpenter, L. Masinter, "Format for Literal IPv6
Addresses in URL's, RFC 2732, December 1999.
[11]
P. Leach, C. Newman, "Using Digest Authentication as a SASL Mechan-
ism", RFC 2831, May 2000
[12]
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J. Hodges, R. Morgan, M. Wahl, "Lightweight Directory Access Proto-
col [v3]: Extension for Transport Layer Security", RFC 2830, May
2000
[13]
Microsoft Corporation, "Services for Unix 2.0",
http://www.microsoft.com/WINDOWS2000/sfu/default.asp
[14]
L. Howard, "An Approach for Using LDAP as a Network Information
Service", RFC 2307, March 1998.
[RFC2251]
M. Wahl, T. Howes, S. Kille, "Lightweight Directory Access Protocol
(v3)", RFC 2251, December 1997.
[RFC2119]
S. Bradner, "Key Words for use in RFCs to Indicate Requirement Lev-
els", RFC 2119, March 1997.
[LDIF]
G. Good, "The LDAP Data Interchange Format (LDIF) - Technical
Specification", RFC 2849, June 2000.
10. Author's Addresses
Luke Howard
PADL Software Pty. Ltd.
PO Box 59
Central Park Vic 3145
Australia
EMail: lukeh@padl.com
Bob Joslin
Hewlett-Packard Company
19420 Homestead RD MS43-LF
Cupertino, CA 95014
USA
Phone: +1 408 447-3044
EMail: bob_joslin@hp.com
Morteza Ansari
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Sun Microsystems, Inc.
901 San Antonio RD MS MPK17-203
Palo Alto, CA 94303
USA
Phone: +1 650 786-6178
EMail: morteza.ansari@sun.com
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