Hi,
Thank you for your response. What you wrote makes sense, and it was definitely my mistake.
I have made the necessary changes in the settings.
auth_bind_userdn = cn=%u,ou=Users,dc=example,dc=com

I changed the user's cn to user@example.com.

It appears that there is indeed a specific BIND attempt for this user. However, it does not resolve the issues with olcAccess.
If I change the last olcAccess entry from "olcAccess: {10} to * by * read" to "olcAccess: {10} to * by anonymous auth," the anonymous user cannot browse LDAP, but the mail client user also cannot log in.

The LDAP server logs contain the following entries:

May 17 07:37:11 ldap0 slapd[262]: conn=1069 fd=14 ACCEPT from IP=192.168.204.94:45490 (IP=0.0.0.0:389)
May 17 07:37:11 ldap0 slapd[262]: conn=1069 op=0 BIND dn="" method=128
May 17 07:37:11 ldap0 slapd[262]: conn=1069 op=0 RESULT tag=97 err=0 text=
May 17 07:37:11 ldap0 slapd[262]: conn=1069 op=1 BIND dn="cn=user@example.com,ou=Users,dc=example,dc=com" method=128
May 17 07:37:11 ldap0 slapd[262]: conn=1069 op=1 BIND dn="cn=user@example.com,ou=Users,dc=example,dc=com" mech=SIMPLE ssf=0
May 17 07:37:11 ldap0 slapd[262]: conn=1069 op=1 RESULT tag=97 err=0 text=
May 17 07:37:11 ldap0 slapd[262]: conn=1069 op=2 BIND anonymous mech=implicit ssf=0
May 17 07:37:11 ldap0 slapd[262]: conn=1069 op=2 BIND dn="" method=128
May 17 07:37:11 ldap0 slapd[262]: conn=1069 op=2 RESULT tag=97 err=0 text=
May 17 07:37:11 ldap0 slapd[262]: conn=1069 op=3 SRCH base="ou=Users,dc=example,dc=com" scope=2 deref=0 filter="(&(objectClass=posixAccount)(uid=user@example.com))"
May 17 07:37:11 ldap0 slapd[262]: conn=1069 op=3 SRCH attr=mail homeDirectory uidNumber gidNumber
May 17 07:37:11 ldap0 slapd[262]: conn=1069 op=3 SEARCH RESULT tag=101 err=50 nentries=0 text=

The tag 101 corresponds to the search request response operation, and err=50 indicates insufficient access rights.
In the logs, we can see the event "BIND anonymous mech=implicit ssf=0," which suggests that Dovecot is attempting to connect anonymously.
The same thing happens when I perform such a query using ldapsearch and using the user user@example.com on the LDAP server console.
In the logs, there is SEARCH RESULT tag=101 err=32 nentries=0 text=.

On Wed, May 17, 2023 at 8:12 AM Mihai Badici <mihai@badici.ro> wrote:

I think you need also add "by users read" but the problem in this setup is to find the user you have a filter so you need to search for this .

So you need either specify a special binding account or the format of the biding user

This is from the default config on debian :

# For example:
# auth_bind_userdn = cn=%u,ou=people,o=org
#

On 5/17/23 08:57, Andrzej Milewski wrote:
Hi,
I'm trying to set up a production mail server. I have installed Dovecot on Debian from the package. For authentication, I have another machine running OpenLDAP, also installed on Debian. I would like the end mail client to authenticate with Dovecot using the login and password set in LDAP.

In the LDAP-related configuration, I have:
auth_bind=yes
base = ou=Users,dc=example,dc=com
user_attrs = mail=couriermaildir:~/Maildir,homeDirectory=/home/%d/%uid/,uidNumber=uid,gidNumber=gid
user_filter = (&(objectClass=posixAccount)(uid=%u))
pass_attrs = uid=user,userPassword=password,\
pass_filter = (&(objectClass=posixAccount)(uid=%u))

The LDAP user is entered as uid=user@example.com. With the default olcAccess permissions, it works and logs in correctly.

Here are my default olcAccess settings after installation:
# {1}mdb, config
dn: olcDatabase={1}mdb,cn=config
objectClass: olcDatabaseConfig
objectClass: olcMdbConfig
olcDatabase: {1}mdb
olcDbDirectory: /var/lib/ldap
olcSuffix: dc=example,dc=com
olcAccess: {0}to dn.children="ou=Idmaps,dc=example,dc=com" attrs=userPassword,
shadowLastChange,SambaLMPassword,SambaNTPassword by self write by anonymous a
uth by dn="cn=samba,dc=example,dc=com" write by dn="cn=admin,dc=laktopol,dc=p
l" write by * none
olcAccess: {1}to dn.subtree="ou=Idmaps,dc=example,dc=com" by self write by dn=
"cn=samba,dc=example,dc=com" write by dn="cn=admin,dc=example,dc=com" write b
y * read
olcAccess: {2}to dn.children="ou=Hosts,dc=example,dc=com" attrs=userPassword,s
hadowLastChange,SambaLMPassword,SambaNTPassword by self write by anonymous au
th by dn="cn=samba,dc=example,dc=com" write by dn="cn=admin,dc=example,dc=com
" write by * none
olcAccess: {3}to dn.subtree="ou=Hosts,dc=example,dc=com" by self write by dn="
cn=samba,dc=example,dc=com" write by dn="cn=admin,dc=example,dc=com" write by
* read
olcAccess: {4}to dn.children="ou=Users,dc=example,dc=com" attrs=userPassword,s
hadowLastChange,SambaLMPassword,SambaNTPassword by self write by anonymous au
th by dn="cn=samba,dc=example,dc=com" write by dn="cn=nsspam,dc=laktopol,dc=p
l" write by dn="cn=admin,dc=example,dc=com" write by * none
olcAccess: {5}to dn.children="ou=Users,dc=example,dc=com" by self write by dn=
"cn=samba,dc=example,dc=com" write by dn="cn=nsspam,dc=example,dc=com" write
by dn="cn=admin,dc=example,dc=com" write by * read
olcAccess: {6}to filter=(objectClass=sambaDomain) by dn="cn=samba,dc=laktopol,
dc=pl" write by dn="cn=admin,dc=example,dc=com" write by * read
olcAccess: {7}to dn.base="dc=example,dc=com" attrs=children by dn="cn=samba,dc
=laktopol,dc=pl" write by dn="cn=admin,dc=example,dc=com" write by * read
olcAccess: {8}to attrs=userPassword,shadowLastChange,SambaLMPassword,SambaNTPa
ssword by self write by anonymous auth by dn="cn=nsspam,dc=example,dc=com" wr
ite by dn="cn=admin,dc=example,dc=com" write by * none
olcAccess: {9}to attrs=shadowLastChange by self write by * read
olcAccess: {10} to * by * read

However, I am not satisfied with these settings because using the anonymous user, anyone can browse the entire LDAP tree. While passwords are not visible with anonymous login, user data in the LDAP domain is exposed.

If I change the last olcAccess entry from "olcAccess: {10} to * by * read" to "olcAccess: {10} to * by anonymous auth," the anonymous user cannot browse LDAP, but the mail client user also cannot log in.

What should be the correct configuration?

--
Andrzej
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Andrzej