Re: Question regarding order of SASL authentication mechanisms

From: Markus Moeller (no email)
Date: Sat Dec 06 2008 - 14:14:30 EST

  • Next message: Dan White: "Re: Question regarding order of SASL authentication mechanisms"

    Dieter,

    It doesn't work as you described or GSSAPI is weaker than DIGEST-MD5

    With /etc/sasl2/slapd.conf
    mech_list: gssapi digest-md5 external

    I get:

     # ldapsearch -h localhost -b "" -s base +
    SASL/DIGEST-MD5 authentication started
    Please enter your password:

    with /etc/sasl2/sladp.conf
    mech_list: gssapi external

    I get:

    ldapsearch -h localhost -b "" -s base +
    SASL/GSSAPI authentication started
    SASL username:
    SASL SSF: 56
    SASL data security layer installed.
    # extended LDIF
    #
    # LDAPv3
    # base <> with scope baseObject
    # filter: (objectclass=*)
    # requesting: +
    #

    #
    dn:
    structuralObjectClass: OpenLDAProotDSE
    configContext: cn=config
    namingContexts: dc=suse,dc=home
    supportedControl: 1.3.6.1.4.1.4203.1.9.1.1
    supportedControl: 2.16.840.1.113730.3.4.18
    supportedControl: 2.16.840.1.113730.3.4.2
    supportedControl: 1.3.6.1.4.1.4203.1.10.1
    supportedControl: 1.2.840.113556.1.4.319
    supportedControl: 1.2.826.0.1.3344810.2.3
    supportedControl: 1.3.6.1.1.13.2
    supportedControl: 1.3.6.1.1.13.1
    supportedControl: 1.3.6.1.1.12
    supportedExtension: 1.3.6.1.4.1.1466.20037
    supportedExtension: 1.3.6.1.4.1.4203.1.11.1
    supportedExtension: 1.3.6.1.4.1.4203.1.11.3
    supportedExtension: 1.3.6.1.1.8
    supportedFeatures: 1.3.6.1.1.14
    supportedFeatures: 1.3.6.1.4.1.4203.1.5.1
    supportedFeatures: 1.3.6.1.4.1.4203.1.5.2
    supportedFeatures: 1.3.6.1.4.1.4203.1.5.3
    supportedFeatures: 1.3.6.1.4.1.4203.1.5.4
    supportedFeatures: 1.3.6.1.4.1.4203.1.5.5
    supportedLDAPVersion: 3
    supportedSASLMechanisms: GSSAPI
    entryDN:
    subschemaSubentry: cn=Subschema

    # search result
    search: 5
    result: 0 Success

    # numResponses: 2
    # numEntries: 1

    Markus

    "Dieter Kluenter" <> wrote in message
    news:...
    "Markus Moeller" <> writes:

    > I'd like to use for ldap bind GSSAPI as the first sasl authentication
    > mechanism and digest-md5 as the second prefered method (e.g. if the
    > client does not support GSSAPI)
    >
    > I have configured slapd with /etc/sash/slapd.conf that has gssapi
    > before digest-md5 (I assume the order is important, is it?) .

    No, it is not important, as sasl selects the most appropriate
    mechanism.

    > mech_list: gssapi digest-md5 cram-md5 external
    >
    > But despite the above order I get gssapi as the last in the list of
    > supportedsaslmechanisms
    >
    > #ldapsearch -H ldap://192.168.1.27 -x -D "CN=Admin,DC=Suse,DC=home" -w
    > password -b "" -s base "supportedsaslmechanisms"
    > # extended LDIF
    > #
    > # LDAPv3
    > # base <> with scope baseObject
    > # filter: (objectclass=*)
    > # requesting: supportedsaslmechanisms
    > #
    >
    > #
    > dn:
    > supportedSASLMechanisms: DIGEST-MD5
    > supportedSASLMechanisms: CRAM-MD5
    > supportedSASLMechanisms: GSSAPI

    The ldap protocol is a message based protocol and there are no ordering
    rules defined to present results. Ordering of search results is left
    to the clients.

    > # search result
    > search: 2
    > result: 0 Success
    >
    > # numResponses: 2
    > # numEntries: 1
    >
    > and a query will force digest-md5 authentication (despite the GSSAPI
    > capability of the client).
    >
    > #ldapsearch -H ldap://192.168.1.27 -s base -b "" "supportedsaslmechanisms"
    > SASL/DIGEST-MD5 authentication started
    > Please enter your password:
    >
    > If I change /etc/sasl2/slapd.conf to
    >
    > mech_list: gssapi
    >
    > I get gssapi to work
    >
    > #ldapsearch -H ldap://192.168.1.27 -b "" -s base "supportedsaslmechanisms"
    > SASL/GSSAPI authentication started
    > SASL username:
    > SASL SSF: 56
    > SASL installing layers
    > # extended LDIF
    > #
    > # LDAPv3
    > # base <> with scope baseObject
    > # filter: (objectclass=*)
    > # requesting: supportedsaslmechanisms
    > #
    >
    > #
    > dn:
    > supportedSASLMechanisms: GSSAPI
    >
    > # search result
    > search: 5
    > result: 0 Success
    >
    > # numResponses: 2
    > # numEntries: 1
    >
    >
    > What do I need to do to force the order on the server ?

    This is not necessary, The strong bind authentication is not done by
    slapd but passed to the sasl framework, sasl selects the most secure
    mechanism available, that is in your case GSSAPI. Just test it by
    calling ldapsearch without any bind options, something like:
    ldapsearch -h localhost -b "" -s base +

    -Dieter

    -- 
    Dieter Klünter | Systemberatung
    http://www.dpunkt.de/buecher/2104.html
    sip: +49.180.1555.7770535
    GPG Key ID:8EF7B6C6
    53°08'09,95"N
    10°08'02,42"E
    

  • Next message: Dan White: "Re: Question regarding order of SASL authentication mechanisms"





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