> On Jul 19, 2018, at 6:49 PM, J Doe <[email protected]
> <mailto:[email protected]>> wrote:
>
> Hello,
>
> I have a basic e-mail server with Postfix 3.1 and Dovecot 2.2.22.
>
> I am using a passwd-file for both userdb and passdb:
>
> /etc/dovecot/dovecot.conf
> userdb {
> driver = passwd-file
> args = /etc/dovecot/passwd
> }
>
> passdb {
> driver = passwd-file
> args = /etc/dovecot/passwd
> }
> }
>
> In the passwd file, I want to have user account names for SMTP SASL AUTH and
> IMAP that are NOT e-mail addresses.
>
> For example, employee one of ABC corp would have a SMTP SASL AUTH/IMAP
> account name in the form: abc_company_employeeid (for example:
> abc_company_03284). The idea behind that is that I do not want someone
> outside of the company to be able to know the first half of the username and
> password pair just because they have an employee's e-mail address.
>
> For the e-mail address I specify something like: [email protected]
> <mailto:[email protected]> however I never want someone to be able to login via
> their e-mail address. Originally, I specified the password field as empty,
> with the understanding being that the default encryption of a password is
> {CRYPT}. Since crypt() cannot output a null string, this meant that there
> was never a valid password.
>
> So passwd looked like this:
>
> /etc/dovecot/passwd
> # SMTP SASL AUTH and IMAP accounts
>
> abc_company_03284:::::::userdb_mail=maildir:/var/mail/vhosts/abc.com/abc_company_03284
> <http://abc.com/abc_company_03284>
>
> # IMAP
> [email protected]
> <mailto:[email protected]>:vmail:vmail::/home/vmail/bob::userdb_maill=maildir:/var/mail/vhosts/abc.com/abc_company_03284
> <http://abc.com/abc_company_03284>
>
> I tested SMTP SASL AUTH and IMAP via the openssl s_client and can confirm
> that I can login and send e-mail as well as retrieve mail only via the:
> abc_company_03284 account, but because an empty password field isn’t
> mentioned on the Dovecot wiki, I was wondering if I should add “nologin” to
> explicitly make it impossible for: [email protected] <mailto:[email protected]>.
> “nologin” was mentioned to me in a previous e-mail to this list.
>
> So passwd would now look like this:
>
> /etc/dovecot/passwd
> # SMTP SASL AUTH and IMAP accounts
>
> abc_company_03284:::::::userdb_mail=maildir:/var/mail/vhosts/abc.com/abc_company_03284
> <http://abc.com/abc_company_03284>
>
> # IMAP
> [email protected]
> <mailto:[email protected]>:vmail:vmail::/home/vmail/bob::userdb_mail=maildir:/var/mail/vhosts/abc.com/abc_company_03284
> <http://abc.com/abc_company_03284> nologin
>
> I restarted Dovecot and tested this with openssl s_client for SMTP SASL AUTH
> and IMAP, but just wanted to make sure that this STOPS ANY LOGINS via the
> e-mail address: [email protected] <mailto:[email protected]> ?
>
> Thanks,
>
> - J
Hi list,
I believe I’ve found the solution I’m looking for.
I use one passwd-file for SMTP SASL AUTH, IMAP and LMTP from a Postfix 3.1
server to a Dovecot 2.2.22 server.
/etc/dovecot/dovecot.conf
userdb {
driver = passwd-file
args = /etc/dovecot/passwd
}
passdb {
driver = passwd-file
args = /etc/dovecot/passwd
}
}
The passwd file contains one test user. The test user’s SMTP SASL AUTH and
IMAP account name is: “abc_company_03284" and has a password of “password”.
The e-mail address of that user is "[email protected] <mailto:[email protected]>". I
don’t have the SMTP SASL AUTH and IMAP account name set to “[email protected]
<mailto:[email protected]>" because I don’t want someone to try to login by assuming
the SMTP SASL AUTH/IMAP account name is the user’s e-mail address.
/etc/dovecot/passwd
# SMTP SASL AUTH and IMAP information
abc_company_03284:{PLAIN}password::::::userdb_mail=maildir:/var/mail/vhosts/abc.com/abc_company_03284
<http://abc.com/abc_company_03284>
# LMTP
[email protected]
<mailto:[email protected]>:{PLAIN}password:vmail:vmail:/home/vmail/bob::userdb_mail=maildir:/var/mail/vhosts/abc.com/abc_company_03284
<http://abc.com/abc_company_03284>
If I test logging on via SMTP SASL AUTH and IMAP via the openssl s_client, I
can log on using an account name of “[email protected]" and a password of
“password”, as expected.
To stop someone from logging on via their e-mail address, I place “fail” [1] at
the end INSTEAD OF “nologin”:
/etc/dovecot/passwd
# SMTP SASL AUTH and IMAP information
abc_company_03284:{PLAIN}password::::::userdb_mail=maildir:/var/mail/vhosts/abc.com/abc_company_03284
<http://abc.com/abc_company_03284>
# LMTP
[email protected]
<mailto:[email protected]>:{PLAIN}password:vmail:vmail:/home/vmail/bob::userdb_mail=maildir:/var/mail/vhosts/abc.com/abc_company_03284
<http://abc.com/abc_company_03284> fail
If I then restart Postfix and Dovecot and attempt to login via SMTP SASL AUTH
and IMAP via the openssl s_client with an account name of “[email protected]
<mailto:[email protected]>” and use a password of “password”, it now fails password
lookup in both instances. Because of the “fail” command, the password field I
used for testing with the “[email protected] <mailto:[email protected]>" account is
irrelevant and I can remove it. Therefore my final passwd file is:
/etc/dovecot/passwd
# SMTP SASL AUTH and IMAP information
abc_company_03284:{PLAIN}password::::::userdb_mail=maildir:/var/mail/vhosts/abc.com/abc_company_03284
<http://abc.com/abc_company_03284>
# LMTP
[email protected]
<mailto:[email protected]>::vmail:vmail:/home/vmail/bob::userdb_mail=maildir:/var/mail/vhosts/abc.com/abc_company_03284
<http://abc.com/abc_company_03284> fail
Sending a test e-mail to “[email protected] <mailto:[email protected]>” confirms that the
user’s e-mail is received and stored in:
"/var/mail/vhosts/abc.com/abc_company_03284
<http://abc.com/abc_company_03284>”, which means LMTP is working.
Can anyone confirm that I am correct about this ? I want to be sure that is
now:
1) Impossible to login via SMTP SASL AUTH and IMAP using the e-mail address
“[email protected] <mailto:[email protected]>”.
2) Only possible to login via SMTP SASL AUTH and IMAP using the account
name “abc_company_03284” and a password of “password"
Thanks,
- J
Sources:
[1] https://wiki2.dovecot.org/PasswordDatabase/ExtraFields
<https://wiki2.dovecot.org/PasswordDatabase/ExtraFields> and see “fail"
