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docker-mailserver/docs/content/config/advanced/auth-ldap.md
Casper ea81aebf83
Follow-up #2035 (#2047) 
* remove volumes section

* bind mounts + localtime
2021-06-21 17:36:59 +02:00

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---
title: 'Advanced | LDAP Authentication'
---
## Introduction
Getting started with ldap and this mailserver we need to take 3 parts in account:
- `postfix` for incoming & outgoing email
- `dovecot` for accessing mailboxes
- `saslauthd` for SMTP authentication (this can also be delegated to dovecot)
## Variables to Control Provisioning by the Container
Have a look at [the ENV page][docs-environment] for information on the default values.
### `LDAP_QUERY_FILTER_*`
Those variables contain the LDAP lookup filters for postfix, using `%s` as the placeholder for the domain or email address in question. This means that...
- ...for incoming email, the domain must return an entry for the `DOMAIN` filter (see [`virtual_alias_domains`](http://www.postfix.org/postconf.5.html#virtual_alias_domains)).
- ...for incoming email, the inboxes which receive the email are chosen by the `USER`, `ALIAS` and `GROUP` filters.
- The `USER` filter specifies personal mailboxes, for which only one should exist per address, for example `(mail=%s)` (also see [`virtual_mailbox_maps`](http://www.postfix.org/postconf.5.html#virtual_mailbox_maps))
- The `ALIAS` filter specifies aliases for mailboxes, using [`virtual_alias_maps`](http://www.postfix.org/postconf.5.html#virtual_alias_maps), for example `(mailAlias=%s)`
- The `GROUP` filter specifies the personal mailboxes in a group (for emails that multiple people shall receive), using [`virtual_alias_maps`](http://www.postfix.org/postconf.5.html#virtual_alias_maps), for example `(mailGroupMember=%s)`
- Technically, there is no difference between `ALIAS` and `GROUP`, but ideally you should use `ALIAS` for personal aliases for a singular person (like `ceo@example.org`) and `GROUP` for multiple people (like `hr@example.org`).
- ...for outgoing email, the sender address is put through the `SENDERS` filter, and only if the authenticated user is one of the returned entries, the email can be sent.
- This only applies if `SPOOF_PROTECTION=1`.
- If the `SENDERS` filter is missing, the `USER`, `ALIAS` and `GROUP` filters will be used in in a disjunction (OR).
- To for example allow users from the `admin` group to spoof any sender email address, and to force everyone else to only use their personal mailbox address for outgoing email, you can use something like this: `(|(memberOf=cn=admin,*)(mail=%s))`
???+ example
A really simple `LDAP_QUERY_FILTER` configuration, using only the _user filter_ and allowing only `admin@*` to spoof any sender addresses.
```yaml
- ENABLE_LDAP=1
- LDAP_SERVER_HOST=ldap.example.org
- LDAP_SEARCH_BASE=dc=example,dc=org"
- LDAP_BIND_DN=cn=admin,dc=example,dc=org
- LDAP_BIND_PW=mypassword
- SPOOF_PROTECTION=1
- LDAP_QUERY_FILTER_DOMAIN=(mail=*@%s)
- LDAP_QUERY_FILTER_USER=(mail=%s)
- LDAP_QUERY_FILTER_ALIAS=(|) # doesn't match anything
- LDAP_QUERY_FILTER_GROUP=(|) # doesn't match anything
- LDAP_QUERY_FILTER_SENDERS=(|(mail=%s)(mail=admin@*))
```
### `DOVECOT_*_FILTER` & `DOVECOT_*_ATTRS`
These variables specify the LDAP filters that dovecot uses to determine if a user can log in to their IMAP account, and which mailbox is responsible to receive email for a specific postfix user.
This is split into the following two lookups, both using `%u` as the placeholder for the full login name ([see dovecot documentation for a full list of placeholders](https://doc.dovecot.org/configuration_manual/config_file/config_variables/)). Usually you only need to set `DOVECOT_USER_FILTER`, in which case it will be used for both filters.
- `DOVECOT_USER_FILTER` is used to get the account details (uid, gid, home directory, quota, ...) of a user.
- `DOVECOT_PASS_FILTER` is used to get the password information of the user, and is in pretty much all cases identical to `DOVECOT_USER_FILTER` (which is the default behaviour if left away).
If your directory doesn't have the [postfix-book schema](https://github.com/variablenix/ldap-mail-schema/blob/master/postfix-book.schema) installed, then you must change the internal attribute handling for dovecot. For this you have to change the `pass_attr` and the `user_attr` mapping, as shown in the example below:
```yaml
- DOVECOT_PASS_ATTRS=<YOUR_USER_IDENTIFIER_ATTRIBUTE>=user,<YOUR_USER_PASSWORD_ATTRIBUTE>=password
- DOVECOT_USER_ATTRS=<YOUR_USER_HOME_DIRECTORY_ATTRIBUTE>=home,<YOUR_USER_MAILSTORE_ATTRIBUTE>=mail,<YOUR_USER_MAIL_UID_ATTRIBUTE>=uid,<YOUR_USER_MAIL_GID_ATTRIBUTE>=gid
```
!!! note
For `DOVECOT_*_ATTRS`, you can replace `ldapAttr=dovecotAttr` with `=dovecotAttr=%{ldap:ldapAttr}` for more flexibility, like for example `=home=/var/mail/%{ldap:uid}` or just `=uid=5000`.
A list of dovecot attributes can be found [in the dovecot documentation](https://doc.dovecot.org/configuration_manual/authentication/user_databases_userdb/#authentication-user-database).
???+ example "Defaults"
```yaml
- DOVECOT_USER_ATTRS=mailHomeDirectory=home,mailUidNumber=uid,mailGidNumber=gid,mailStorageDirectory=mail
- DOVECOT_PASS_ATTRS=uniqueIdentifier=user,userPassword=password
- DOVECOT_USER_FILTER=(&(objectClass=PostfixBookMailAccount)(uniqueIdentifier=%n))
```
???+ example
Setup for a directory that has the [qmail-schema](https://github.com/amery/qmail/blob/master/qmail.schema) installed and uses `uid`:
```yaml
- DOVECOT_PASS_ATTRS=uid=user,userPassword=password
- DOVECOT_USER_ATTRS=homeDirectory=home,qmailUID=uid,qmailGID=gid,mailMessageStore=mail
- DOVECOT_USER_FILTER=(&(objectClass=qmailUser)(uid=%u)(accountStatus=active))
```
The LDAP server configuration for dovecot will be taken mostly from postfix, other options can be found in [the environment section in the docs][docs-environment].
### `DOVECOT_AUTH_BIND`
Set this to `yes` to enable authentication binds ([more details in the dovecot documentation](https://wiki.dovecot.org/AuthDatabase/LDAP/AuthBinds)). Currently, only DN lookup is supported without further changes to the configuration files, so this is only useful when you want to bind as a readonly user without the permission to read passwords.
### `SASLAUTHD_LDAP_FILTER`
This filter is used for `saslauthd`, which is called by postfix when someone is authenticating through SMTP (assuming that `SASLAUTHD_MECHANISMS=ldap` is being used). Note that you'll need to set up the LDAP server for saslauthd seperately from postfix.
The filter variables are explained in detail [in the `LDAP_SASLAUTHD` file](https://github.com/winlibs/cyrus-sasl/blob/master/saslauthd/LDAP_SASLAUTHD#L121), but unfortunately, this method doesn't really support domains right now - that means that `%U` is the only token that makes sense in this variable.
!!! note "When to use this and how to avoid it"
Using a separate filter for SMTP authentication allows you to for example allow `noreply@example.org` to send email, but not log in to IMAP or receive email: `(&(mail=%U@example.org)(|(memberOf=cn=email,*)(mail=noreply@example.org)))`
If you don't want to use a separate filter for SMTP authentication, you can set `SASLAUTHD_MECHANISMS=rimap` and `SASLAUTHD_MECH_OPTIONS=127.0.0.1` to authenticate against dovecot instead - this means that the `DOVECOT_USER_FILTER` and `DOVECOT_PASS_FILTER` will be used for SMTP authentication as well.
???+ example "Configure LDAP with `saslauthd`"
```yaml
- ENABLE_SASLAUTHD=1
- SASLAUTHD_MECHANISMS=ldap
- SASLAUTHD_LDAP_FILTER=(mail=%U@example.org)
```
## Secure Connection with LDAPS or StartTLS
To enable LDAPS, all you need to do is to add the protocol to `LDAP_SERVER_HOST`, for example `ldaps://example.org:636`.
To enable LDAP over StartTLS (on port 389), you need to set the following environment variables instead (the **protocol must not be `ldaps://`** in this case!):
```yaml
- LDAP_START_TLS=yes
- DOVECOT_TLS=yes
- SASLAUTHD_LDAP_START_TLS=yes
```
## LDAP Setup Examples
???+ example "Basic Setup"
```yaml
version: '2'
services:
mail:
image: mailserver/docker-mailserver:latest
hostname: mail
domainname: example.org
container_name: mail
ports:
- "25:25"
- "143:143"
- "587:587"
- "993:993"
volumes:
- ./data/maildata:/var/mail
- ./data/mailstate:/var/mail-state
- ./data/maillogs:/var/log/mail
- /etc/localtime:/etc/localtime:ro
- ./config/:/tmp/docker-mailserver/
environment:
- ENABLE_SPAMASSASSIN=1
- ENABLE_CLAMAV=1
- ENABLE_FAIL2BAN=1
- ENABLE_POSTGREY=1
# >>> Postfix LDAP Integration
- ENABLE_LDAP=1
- LDAP_SERVER_HOST=ldap.example.org
- LDAP_BIND_DN=cn=admin,ou=users,dc=example,dc=org
- LDAP_BIND_PW=mypassword
- LDAP_SEARCH_BASE=dc=example,dc=org
- LDAP_QUERY_FILTER_DOMAIN=(|(mail=*@%s)(mailAlias=*@%s)(mailGroupMember=*@%s))
- LDAP_QUERY_FILTER_USER=(&(objectClass=inetOrgPerson)(mail=%s))
- LDAP_QUERY_FILTER_ALIAS=(&(objectClass=inetOrgPerson)(mailAlias=%s))
- LDAP_QUERY_FILTER_GROUP=(&(objectClass=inetOrgPerson)(mailGroupMember=%s))
- LDAP_QUERY_FILTER_SENDERS=(&(objectClass=inetOrgPerson)(|(mail=%s)(mailAlias=%s)(mailGroupMember=%s)))
- SPOOF_PROTECTION=1
# <<< Postfix LDAP Integration
# >>> Dovecot LDAP Integration
- DOVECOT_USER_FILTER=(&(objectClass=inetOrgPerson)(mail=%u))
- DOVECOT_PASS_ATTRS=uid=user,userPassword=password
- DOVECOT_USER_ATTRS==home=/var/mail/%{ldap:uid},=mail=maildir:~/Maildir,uidNumber=uid,gidNumber=gid
# <<< Dovecot LDAP Integration
# >>> SASL LDAP Authentication
- ENABLE_SASLAUTHD=1
- SASLAUTHD_MECHANISMS=ldap
- SASLAUTHD_LDAP_FILTER=(&(mail=%U@example.org)(objectClass=inetOrgPerson))
# <<< SASL LDAP Authentication
- ONE_DIR=1
- DMS_DEBUG=0
- SSL_TYPE=letsencrypt
- PERMIT_DOCKER=host
cap_add:
- NET_ADMIN
```
??? example "Kopano / Zarafa"
```yaml
version: '2'
services:
mail:
image: mailserver/docker-mailserver:latest
hostname: mail
domainname: domain.com
container_name: mail
ports:
- "25:25"
- "143:143"
- "587:587"
- "993:993"
volumes:
- maildata:/var/mail
- mailstate:/var/mail-state
- ./config/:/tmp/docker-mailserver/
environment:
# We are not using dovecot here
- SMTP_ONLY=1
- ENABLE_SPAMASSASSIN=1
- ENABLE_CLAMAV=1
- ENABLE_FAIL2BAN=1
- ENABLE_POSTGREY=1
- SASLAUTHD_PASSWD=
# >>> SASL Authentication
- ENABLE_SASLAUTHD=1
- SASLAUTHD_LDAP_FILTER=(&(sAMAccountName=%U)(objectClass=person))
- SASLAUTHD_MECHANISMS=ldap
# <<< SASL Authentication
# >>> Postfix Ldap Integration
- ENABLE_LDAP=1
- LDAP_SERVER_HOST=<yourLdapContainer/yourLdapServer>
- LDAP_SEARCH_BASE=dc=mydomain,dc=loc
- LDAP_BIND_DN=cn=Administrator,cn=Users,dc=mydomain,dc=loc
- LDAP_BIND_PW=mypassword
- LDAP_QUERY_FILTER_USER=(&(objectClass=user)(mail=%s))
- LDAP_QUERY_FILTER_GROUP=(&(objectclass=group)(mail=%s))
- LDAP_QUERY_FILTER_ALIAS=(&(objectClass=user)(otherMailbox=%s))
- LDAP_QUERY_FILTER_DOMAIN=(&(|(mail=*@%s)(mailalias=*@%s)(mailGroupMember=*@%s))(mailEnabled=TRUE))
# <<< Postfix Ldap Integration
# >>> Kopano Integration
- ENABLE_POSTFIX_VIRTUAL_TRANSPORT=1
- POSTFIX_DAGENT=lmtp:kopano:2003
# <<< Kopano Integration
- ONE_DIR=1
- DMS_DEBUG=0
- SSL_TYPE=letsencrypt
- PERMIT_DOCKER=host
cap_add:
- NET_ADMIN
volumes:
maildata:
driver: local
mailstate:
driver: local
```
[docs-environment]: ../environment.md
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