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Re: hdb and mdb dereferencing aliases differently

Juergen.Sprenger@swisscom.com wrote:

Hi Michael,

NSS results must not be dependent on the backend database a directory service uses.

I activated connection logging and here's the proof that NSS is not the culprit.

Searches initiated by NSS are identical and exactly this behavior can also be seen  when using ldapsearch from command line with parameters from the log:

# running 'getent passwd' with hdb backend:
Apr 24 09:53:54 openldap-dev slapd[19240]: conn=1000 op=0 BIND dn="cn=itsAgent,ou=customerAgent,dc=scom" method=128
Apr 24 09:53:54 openldap-dev slapd[19240]: conn=1000 op=0 BIND dn="cn=itsAgent,ou=customerAgent,dc=scom" mech=SIMPLE ssf=0
Apr 24 09:53:54 openldap-dev slapd[19240]: conn=1000 op=0 RESULT tag=97 err=0 text=
Apr 24 09:53:54 openldap-dev slapd[19240]: conn=1000 op=1 SRCH base="ou=account,dc=its,dc=scom" scope=1 deref=3 filter="(objectClass=posixAccount)"
Apr 24 09:53:54 openldap-dev slapd[19240]: conn=1000 op=1 SRCH attr=uid userPassword uidNumber gidNumber cn homeDirectory x-LinuxLoginShell gecos description objectClass
Apr 24 09:53:54 openldap-dev slapd[19240]: conn=1000 op=1 SEARCH RESULT tag=101 err=0 nentries=656 text=
Apr 24 09:53:54 openldap-dev slapd[19240]: conn=1000 fd=13 closed (connection lost)

# running 'getent passwd' with mdb backend:
Apr 24 10:00:17 openldap-dev slapd[19300]: conn=1002 op=0 BIND dn="cn=itsAgent,ou=customerAgent,dc=scom" method=128
Apr 24 10:00:17 openldap-dev slapd[19300]: conn=1002 op=0 BIND dn="cn=itsAgent,ou=customerAgent,dc=scom" mech=SIMPLE ssf=0
Apr 24 10:00:17 openldap-dev slapd[19300]: conn=1002 op=0 RESULT tag=97 err=0 text=
Apr 24 10:00:17 openldap-dev slapd[19300]: conn=1002 op=1 SRCH base="ou=account,dc=its,dc=scom" scope=1 deref=3 filter="(objectClass=posixAccount)"
Apr 24 10:00:17 openldap-dev slapd[19300]: conn=1002 op=1 SRCH attr=uid userPassword uidNumber gidNumber cn homeDirectory x-LinuxLoginShell gecos description objectClass
Apr 24 10:00:17 openldap-dev slapd[19300]: conn=1002 op=1 SEARCH RESULT tag=101 err=0 text=
Apr 24 10:00:17 openldap-dev slapd[19300]: conn=1002 fd=13 closed (connection lost)

I suspect that aliases are not handled the same way in hdb and mdb as I am using aliases here and deref=3 in both searches, example:

dn: uid=joe,ou=Account,dc=its,dc=scom
objectClass: alias
objectClass: extensibleObject
uid: joe
aliasedObjectName: uid=joe,ou=Person,dc=its,dc=scom
structuralObjectClass: alias

When using hdb, the alias is dereferenced correctly (nentries=656), when using mdb it seems not to be dereferenced at all (nentries=0).

Maybe there's a parameter around for mdb which I couldn't find in the docs

to prevent this, but if not I consider this as a bug.
There is no parameter. Seems like you've found a bug, please submit the info to the ITS. 

Regards

Juergen

michael@stroeder.com wrote:

It would certainly help if you could examine the issue with pure LDAP search
operations preferably with OpenLDAP's ldapsearch command-line tool.

When looking at NSS results too many things can go wrong with other
components' configuration.

Ciao, Michael.

Juergen.Sprenger@swisscom.com wrote:

Hi,

I have running OpenDLAP 2.4.35 on  Gentoo Linux and wanted to make some tests with mdb.

Slapd was running fine with hdb, no problems so far.
Then I exported contents via slapcat and switched config to mdb.
When slapd started using mdb no users from directory were shown by 'getent passwd':

### hdb part ####
# using hdb parameters
database        hdb
dirtyread
cachesize       150000
cachefree          100
idlcachesize    450000
dncachesize     100000

# slapadd from backup and run slapd with hdb backend
/etc/init.d/unscd stop
/etc/init.d/slapd stop
rm /var/lib/openldap-data/*
rm -rf /etc/openldap/slapd.d/*
cp -p /etc/openldap/DB_CONFIG /var/lib/openldap-data/
cp -p /etc/openldap/slapd.conf.hdb /etc/openldap/slapd.conf
su ldap -c '/usr/sbin/slapadd -f /etc/openldap/slapd.conf -l odsldap-dev.ldif'
/etc/init.d/slapd start
/etc/init.d/unscd start
slapcat -f /etc/openldap/slapd.conf -b dc=scom | md5sum
# 73850f9a3f7ff9d3d1ddb7663cd046a6  -

getent passwd
# all users shown, everything ok

### mdb part ####
# using mdb paramters
database        mdb
dbnosync
maxsize 2094967296
searchstack 64

# slapadd from backup and run slapd with mdb backend
/etc/init.d/unscd stop
/etc/init.d/slapd stop
rm /var/lib/openldap-data/*
rm -rf /etc/openldap/slapd.d/*
cp -p /etc/openldap/slapd.conf.mdb /etc/openldap/slapd.conf
su ldap -c '/usr/sbin/slapadd -f /etc/openldap/slapd.conf -l odsldap-dev.ldif'
/etc/init.d/slapd start
/etc/init.d/unscd start
slapcat -f /etc/openldap/slapd.conf -b dc=scom | md5sum
# 73850f9a3f7ff9d3d1ddb7663cd046a6  -

<>

getent passwd
# no users from ldap shown

Am I missing something  when setting up and using mdb?
Both backends have exactly the same content, and so the results for searches should also be identical.

Regards

Jürgen Sprenger







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  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/