SSL TLS SNI error certificate is empty

[silvan at datavenia.nl]

Hey Christian,

This resolves the issue, thank you. You are also correct in that it is stated here: https://doc.dovecot.org/configuration_manual/dovecot_ssl_configuration/#different-certificates-per-ip-and-protocol
I didn't realize it was also applicable to TLS SNI, but I should have tested.

Regards,
Silvan

-----Original Message-----
From: dovecot <dovecot-bounces at dovecot.org> On Behalf Of Christian Kivalo
Sent: Monday, 16 August 2021 19:32
To: dovecot at dovecot.org
Subject: Re: SSL TLS SNI error certificate is empty



On August 16, 2021 3:03:22 AM GMT+02:00, silvan at datavenia.nl wrote:
>Hello,
>
> 
>
>I’ve tried implementing TLS SNI for my Postfix/Dovecot setup. I have it working in Postfix, but this example for Dovecot: https://doc.dovecot.org/configuration_manual/dovecot_ssl_configuration/#with-client-tls-sni-server-name-indication-support doesn’t seem to work for me.
>
> 
>
>I’m using LetsEncrypt certificates. They work without a problem with the regular ssl_cert and ssl_key settings like this:
>
> 
>
>ssl_cert = </docker/rancher-active-proxy/letsencrypt/live/datavenia.nl/fullchain.pem
>
>ssl_key = </docker/rancher-active-proxy/letsencrypt/live/datavenia.nl/privkey.pem
>
> 
>
>… but as soon as I put them in local_name blocks like this:
>
> 
>
>local_name datavenia.nl {
>
>  ssl_cert = </docker/rancher-active-proxy/letsencrypt/live/datavenia.nl/fullchain.pem
>
>  ssl_key = </docker/rancher-active-proxy/letsencrypt/live/datavenia.nl/privkey.pem
>
>}
>
> 
>
>local_name verovia.nl {
>
>  ssl_cert = </docker/rancher-active-proxy/letsencrypt/live/verovia.nl/fullchain.pem
>
>  ssl_key = </docker/rancher-active-proxy/letsencrypt/live/verovia.nl/privkey.pem
>
>}
>
> 
>
>and restart dovecot I get the following error:
>
> 
>
>dovecot: imap-login: Error: Failed to initialize SSL server context: Can't load SSL certificate (ssl_cert setting): The certificate is empty: user=<>, rip=213.127.63.224, lip=142.93.135.7, session=<wKjTIaLJtSXVfz/g>
>
You still need a default ssl_cert outside the local ... block.

This is noted in the section about different certs for different IPs just before the section about SNI


-> Note
-> You will still need a top-level default ssl_key and ssl_cert as well, or you will receive errors.

That default cert ia used as fallback for clients that don't do SNI.

>
>I have verified that the certificate paths are correct, the files have content. I’ve already checked permissions (chmodded 777 to debug), as well as the that these are actually symlinks (updated the config to point to the real files) but nothing so far seems to change anything. I have also recreated my dh.pem (4096).
>
> 
>
>I’m hoping anyone has any idea where I might be going wrong. 
>
> 
>
>Kind regards,
>
>Silvan
>
> 
>
>Output of dovecot -n:
>
> 
>
># 2.3.13 (89f716dc2): /etc/dovecot/dovecot.conf
>
># Pigeonhole version 0.5.13 (cdd19fe3)
>
># OS: Linux 5.11.0-25-generic x86_64 Ubuntu 21.04 ext4
>
># Hostname: azrael00
>
>auth_mechanisms = plain login
>
>mail_location = maildir:/var/mail/vhosts/%d/%n
>
>mail_privileged_group = mail
>
>namespace inbox {
>
>  inbox = yes
>
>  location =
>
>  mailbox Drafts {
>
>    special_use = \Drafts
>
>  }
>
>  mailbox Junk {
>
>    special_use = \Junk
>
>  }
>
>  mailbox Sent {
>
>    special_use = \Sent
>
>  }
>
>  mailbox "Sent Messages" {
>
>    special_use = \Sent
>
>  }
>
>  mailbox Trash {
>
>    special_use = \Trash
>
>  }
>
>  prefix =
>
>}
>
>passdb {
>
>  args = /etc/dovecot/dovecot-sql.conf.ext
>
>  driver = sql
>
>}
>
>postmaster_address = postmaster at datavenia.nl <mailto:postmaster at datavenia.nl> 
>
>protocols = imap lmtp
>
>service auth-worker {
>
>  user = vmail
>
>}
>
>service auth {
>
>  unix_listener /var/spool/postfix/private/auth {
>
>    group = postfix
>
>    mode = 0666
>
>    user = postfix
>
>  }
>
>  unix_listener auth-userdb {
>
>    mode = 0666
>
>    user = vmail
>
>  }
>
>  user = dovecot
>
>}
>
>service imap-login {
>
>  inet_listener imap {
>
>    port = 0
>
>  }
>
>}
>
>service lmtp {
>
>  unix_listener /var/spool/postfix/private/dovecot-lmtp {
>
>    group = postfix
>
>    mode = 0600
>
>    user = postfix
>
>  }
>
>}
>
>ssl = required
>
>ssl_dh = # hidden, use -P to show it
>
>userdb {
>
>  args = uid=vmail gid=vmail home=/var/mail/vhosts/%d/%n
>
>  driver = static
>
>}
>
>local_name datavenia.nl {
>
>  ssl_cert = </docker/rancher-active-proxy/letsencrypt/live/datavenia.nl/fullchain.pem
>
>  ssl_key = # hidden, use -P to show it
>
>}
>
>local_name verovia.nl {
>
>  ssl_cert = </docker/rancher-active-proxy/letsencrypt/live/verovia.nl/fullchain.pem
>
>  ssl_key = # hidden, use -P to show it
>
>}
>

-- 
Christian Kivalo