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Editing: VirtualUsers.txt
Virtual Users ============= There are many ways to configure Dovecot to use virtual users. If you have no idea how you want your users to be configured, select some <HOWTO> [HowTo.txt] and follow its instructions. Users are often categorized as being either system users (in '/etc/passwd') or virtual users (not in '/etc/passwd'). However from Dovecot's point of view there isn't much of a difference between them. If a <passwd> [AuthDatabase.Passwd.txt] lookup and a <SQL> [AuthDatabase.SQL.txt] lookup return the same <userdb> [UserDatabase.txt] information, Dovecot's behavior is identical. Password and user databases --------------------------- Dovecot supports many different <password databases> [PasswordDatabase.txt] and <user databases> [UserDatabase.txt]. With virtual users the most commonly used ones are <LDAP> [AuthDatabase.LDAP.txt], <SQL> [AuthDatabase.SQL.txt] and <passwd-file> [AuthDatabase.PasswdFile.txt]. The databases usually contain the following information: * Username * Password * UNIX User ID (UID) and primary UNIX Group ID (GID) * Home directory and/or mail location Usernames and domains --------------------- Dovecot doesn't care much about domains in usernames. IMAP and POP3 protocols currently have no concept of "domain", so the username is just something that shows up in your logs and maybe in some configuration, but they have no direct functionality. So although Dovecot makes it easier to handle "user@domain" style usernames (eg. %n and %d <variables> [Variables.txt]), nothing breaks if you use for example "domain%user" style usernames instead. However some <authentication mechanisms> [Authentication.Mechanisms.txt] do have an explicit support for realms (pretty much the same as domains). If those mechanisms are used, the username is changed to be "user@realm". And of course there's no need to have domains at all in the usernames. Passwords --------- The password can be in <any format that Dovecot supports> [Authentication.PasswordSchemes.txt], but you need to tell the format to Dovecot because it won't try to guess it. The SQL and LDAP configuration files have the 'default_pass_scheme' setting for this. If you have passwords in multiple formats, or the passdb doesn't have such a setting, you'll need to prefix each password with "{<scheme>}", for example "{PLAIN}plaintext-password" or "{PLAIN-MD5}1a1dc91c907325c69271ddf0c944bc72". UNIX UIDs --------- The most important thing you need to understand is that *Dovecot doesn't access the users' mails as the /dovecot/ user*! So *don't* put /dovecot/ into the /mail/ group, and don't make mails owned by the /dovecot/ user. That will only make your Dovecot installation less secure. So, if not the /dovecot/ user, what then? You can decide that yourself. You can create, for example, one /vmail/ user which owns all the mails, or you can assign a separate UID for each user. See <UserIds#mailusers> [UserIds.txt] for more information about different ways to allocate UIDs for users. UNIX GIDs --------- Unless you're using <shared mailboxes> [SharedMailboxes.txt] and multiple UIDs, it doesn't really matter what GIDs you use. You can, for example, use a single GID for all users, or create a separate GID for each user. See <UserIds#gids> [UserIds.txt] for more information. Home directories ---------------- Some people are opposed to the idea of virtual users having home directories, but no matter what you call it, it's a good idea to have a directory where user-specific configuration and other state is stored. See <VirtualUsers.Home.txt> more information. Mail location ------------- The userdb can return the 'mail' <field> [UserDatabase.txt] to override the default 'mail_location' setting. Usually you shouldn't need this. Examples -------- Dynamic passwd-file locations ----------------------------- ---%<------------------------------------------------------------------------- mail_location = maildir:/home/%d/%n/Maildir passdb { driver = passwd-file args = username_format=%n /home/%d/etc/shadow } userdb { driver = passwd-file args = username_format=%n /home/%d/etc/passwd } ---%<------------------------------------------------------------------------- In the above examples users are expected to log in as "user@domain". Their mail is kept in their home directory at '/home/<domain>/<username>/Maildir'. The usernames in the passwd and shadow files are expected to contain only the user part, no domain. This is because the path itself already contained %d to specify the domain. If you want the files to contain full user@domain names, you can use 'username_format=%u'. static userdb ------------- Many people store only usernames and passwords in their database and don't want to deal with UIDs or GIDs. In that case the easiest way to get Dovecot running is to use the <static userdb> [UserDatabase.Static.txt]: ---%<------------------------------------------------------------------------- mail_location = maildir:~/Maildir passdb { driver = pam } userdb { driver = static args = uid=vmail gid=vmail home=/var/mail/virtual/%d/%n } ---%<------------------------------------------------------------------------- This makes Dovecot look up the mails from '/var/mail/virtual/<domain>/<user>/Maildir/' directory, which should be owned by vmail user and vmail group. Existing virtual user management software ----------------------------------------- * VPopMail [http://www.inter7.com/vpopmail/]: Dovecot <supports VPopMail directly> [AuthDatabase.VPopMail.txt]. * Linuxconf [http://www.solucorp.qc.ca/linuxconf/]: See <Migration.Linuxconf.txt> * Also see the <HowTo.txt> page (This file was created from the wiki on 2019-06-19 12:42)
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