Hi,
I wish to build a new secure email server. It seems I am on the right way – at least I get no more error messages for Postfix – but Dovecot is still making trouble.
I am using Dovecot 1:2.3.4.1-5+deb10u6 and I am using ISPconfig 3.25 to do the rough configuring and nano and whats left of my brain to do the finer details. Lets start with what I added to conf.d/10-ssl.conf
ssl_cert =
ssl_key =
ssl_cipher_list = EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:EECDH+aR$
ssl_protocols = !SSLv2 !SSLv3 !TLSv1 !TLSv1.1
ssl_min_protocol = TLSv1.2
As you can see, I clearly do not want to use TLS before v1.2. I think this is not unreasonable in the year 2021.
Now, after the changes I ran Kali (I use it to verify the results of my experiments)
and - this is a mailing list, so no screenshots:
It says:
SSL/TLS Deprecated TLS v1.0 and TLS v1.1 Detection. I get this for the ports 143, 110, 993 and 995.
I thought I had done everything one could to disable old TLS-Versions. What am I doing wrong?
Yours sincerely
Stefan Schumacher
Interesting.
Assuming your "Kali" tools are in fact up to date to test with newer protocols TLS1.2+, is Dovecot compiled against a recent version of the OpenSSL or GnuTLS library or whatever it uses to support the newer TLS protocols?
Definitely an outdated cipher issue, on Postfix as well as Dovecot....
On July 14, 2021 6:55:19 AM AKDT, Stefan Schumacher s.schumacher@consulting1x1.com wrote:
Hi,
I wish to build a new secure email server. It seems I am on the right way – at least I get no more error messages for Postfix – but Dovecot is still making trouble.
I am using Dovecot 1:2.3.4.1-5+deb10u6 and I am using ISPconfig 3.25 to do the rough configuring and nano and whats left of my brain to do the finer details. Lets start with what I added to conf.d/10-ssl.conf
ssl_cert =
ssl_key =
ssl_cipher_list = EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:EECDH+aR$
ssl_protocols = !SSLv2 !SSLv3 !TLSv1 !TLSv1.1
ssl_min_protocol = TLSv1.2
As you can see, I clearly do not want to use TLS before v1.2. I think this is not unreasonable in the year 2021.
Now, after the changes I ran Kali (I use it to verify the results of my experiments)
and - this is a mailing list, so no screenshots:
It says:
SSL/TLS Deprecated TLS v1.0 and TLS v1.1 Detection. I get this for the ports 143, 110, 993 and 995.
I thought I had done everything one could to disable old TLS-Versions. What am I doing wrong?
Yours sincerely
Stefan Schumacher
-- Sent from my Android device with K-9 Mail. Please excuse my brevity.
Hi Justina,
Kali tools is of course extremly unprecise. Excuse me, I had a long stressful day and wanted to get this out before the end of the Day. Kali is a rolling release, which I update regularly. By Kali Tools I of course meant the Greenbone Community Edition, of which the former and more well-known OpenVAS is now only one possibly multiple scanners.
The mailserver itself is based on Debian which currently 10.10 (11.0 is going to be released in a few days). I upgraded the dovecot components from backports but this caused no change. I am currently considering getting the Bullseye RC2 and then testing on it but I am of course open for any other suggestions. Maybe someone with more knowledge of postfix can add or point out advisable changes to these settings.
Yours sincerely Stefan
smtpd_use_tls = yes smtpd_tls_cert_file = /etc/postfix/smtpd.cert smtpd_tls_key_file = /etc/postfix/smtpd.key smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_tls_eecdh_grade = strong smtpd_tls_protocols= !SSLv2, !SSLv3, !TLSv1, !TLSv1.1 smtpd_tls_mandatory_protocols= !SSLv2, !SSLv3, !TLSv1, !TLSv1.1 smtpd_tls_mandatory_ciphers = high smtpd_tls_security_level=may smtpd_tls_ciphers = high tls_preempt_cipherlist = yes smtpd_tls_mandatory_exclude_ciphers = aNULL, MD5 , DES, ADH, RC4, PSD, SRP, 3DES, eNULL smtpd_tls_exclude_ciphers = aNULL, MD5 , DES, ADH, RC4, PSD, SRP, 3DES, eNULL smtp_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1 smtp_tls_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
Von: justina colmena ~biz justina@colmena.biz Gesendet: Mittwoch, 14. Juli 2021 18:50 An: dovecot@dovecot.org dovecot@dovecot.org; Stefan Schumacher s.schumacher@consulting1x1.com Betreff: Re: TLS Security
Interesting.
Assuming your "Kali" tools are in fact up to date to test with newer protocols TLS1.2+, is Dovecot compiled against a recent version of the OpenSSL or GnuTLS library or whatever it uses to support the newer TLS protocols?
Definitely an outdated cipher issue, on Postfix as well as Dovecot....
On July 14, 2021 6:55:19 AM AKDT, Stefan Schumacher s.schumacher@consulting1x1.com wrote:
Hi,
I wish to build a new secure email server. It seems I am on the right way – at least I get no more error messages for Postfix – but Dovecot is still making trouble.
I am using Dovecot 1:2.3.4.1-5+deb10u6 and I am using ISPconfig 3.25 to do the rough configuring and nano and whats left of my brain to do the finer details. Lets start with what I added to conf.d/10-ssl.conf
ssl_cert =
ssl_key =
ssl_cipher_list = EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:EECDH+aR$
ssl_protocols = !SSLv2 !SSLv3 !TLSv1 !TLSv1.1
ssl_min_protocol = TLSv1.2
As you can see, I clearly do not want to use TLS before v1.2. I think this is not unreasonable in the year 2021.
Now, after the changes I ran Kali (I use it to verify the results of my experiments)
and - this is a mailing list, so no screenshots:
It says:
SSL/TLS Deprecated TLS v1.0 and TLS v1.1 Detection. I get this for the ports 143, 110, 993 and 995.
I thought I had done everything one could to disable old TLS-Versions. What am I doing wrong?
Yours sincerely
Stefan Schumacher
-- Sent from my Android device with K-9 Mail. Please excuse my brevity.
On 14/07/2021 17:55 Stefan Schumacher s.schumacher@consulting1x1.com wrote:
Hi,
I wish to build a new secure email server. It seems I am on the right way – at least I get no more error messages for Postfix – but Dovecot is still making trouble.
I am using Dovecot 1:2.3.4.1-5+deb10u6 and I am using ISPconfig 3.25 to do the rough configuring and nano and whats left of my brain to do the finer details. Lets start with what I added to conf.d/10-ssl.conf
ssl_cert =
ssl_cipher_list = EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:EECDH+aR$ ssl_protocols = !SSLv2 !SSLv3 !TLSv1 !TLSv1.1 ssl_min_protocol = TLSv1.2
As you can see, I clearly do not want to use TLS before v1.2. I think this is not unreasonable in the year 2021.
Now, after the changes I ran Kali (I use it to verify the results of my experiments) and - this is a mailing list, so no screenshots: It says:
SSL/TLS Deprecated TLS v1.0 and TLS v1.1 Detection. I get this for the ports 143, 110, 993 and 995.
I thought I had done everything one could to disable old TLS-Versions. What am I doing wrong?
Yours sincerely Stefan Schumacher
Hi!
First of all, 2.3.4.1 is bit old, and has no proper support for TLSv1.3, which is supported better on a later version. Now, I installed 2.3.4.1 from debian 10, and tested with testssl.sh and got
SSLv2 not offered (OK) SSLv3 not offered (OK) TLS 1 not offered TLS 1.1 not offered TLS 1.2 offered (OK) TLS 1.3 offered (OK): final NPN/SPDY not offered ALPN/HTTP2 not offered
TLSv1.2 (no server order, thus listed by strength)
xc030 ECDHE-RSA-AES256-GCM-SHA384 ECDH 521 AESGCM 256 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
xc028 ECDHE-RSA-AES256-SHA384 ECDH 521 AES 256 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384
xc014 ECDHE-RSA-AES256-SHA ECDH 521 AES 256 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
xcca8 ECDHE-RSA-CHACHA20-POLY1305 ECDH 521 ChaCha20 256 TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256
xc077 ECDHE-RSA-CAMELLIA256-SHA384 ECDH 521 Camellia 256 TLS_ECDHE_RSA_WITH_CAMELLIA_256_CBC_SHA384
xc061 ECDHE-ARIA256-GCM-SHA384 ECDH 521 ARIAGCM 256 TLS_ECDHE_RSA_WITH_ARIA_256_GCM_SHA384
xc02f ECDHE-RSA-AES128-GCM-SHA256 ECDH 521 AESGCM 128 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
xc027 ECDHE-RSA-AES128-SHA256 ECDH 521 AES 128 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
xc013 ECDHE-RSA-AES128-SHA ECDH 521 AES 128 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA
xc076 ECDHE-RSA-CAMELLIA128-SHA256 ECDH 521 Camellia 128 TLS_ECDHE_RSA_WITH_CAMELLIA_128_CBC_SHA256
xc060 ECDHE-ARIA128-GCM-SHA256 ECDH 521 ARIAGCM 128 TLS_ECDHE_RSA_WITH_ARIA_128_GCM_SHA256
TLSv1.3 (no server order, thus listed by strength)
x1302 TLS_AES_256_GCM_SHA384 ECDH 253 AESGCM 256 TLS_AES_256_GCM_SHA384
x1303 TLS_CHACHA20_POLY1305_SHA256 ECDH 253 ChaCha20 256 TLS_CHACHA20_POLY1305_SHA256
x1301 TLS_AES_128_GCM_SHA256 ECDH 253 AESGCM 128 TLS_AES_128_GCM_SHA256
I used:
listen = *
mail_attribute_dict = file:%h/Mail/dovecot-attributes
mail_gid = vmail
mail_home = /home/vmail/%Lu
mail_location = sdbox:~/Mail
mail_uid = vmail
passdb {
args = password=#hidden_use-P_to_show#
driver = static
}
protocols = imap
ssl_cert = Aki
I've found this resource useful in the past
P.
Hi Aki,
Where do I get testssh.sl? If the script is of your design could you mail it to me?
Yours Stefan
Von: Aki Tuomi aki.tuomi@open-xchange.com Gesendet: Mittwoch, 14. Juli 2021 19:34 An: Stefan Schumacher s.schumacher@consulting1x1.com; dovecot@dovecot.org dovecot@dovecot.org Betreff: Re: TLS Security
On 14/07/2021 17:55 Stefan Schumacher s.schumacher@consulting1x1.com wrote:
Hi,
I wish to build a new secure email server. It seems I am on the right way – at least I get no more error messages for Postfix – but Dovecot is still making trouble.
I am using Dovecot 1:2.3.4.1-5+deb10u6 and I am using ISPconfig 3.25 to do the rough configuring and nano and whats left of my brain to do the finer details. Lets start with what I added to conf.d/10-ssl.conf
ssl_cert =
ssl_cipher_list = EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:EECDH+aR$ ssl_protocols = !SSLv2 !SSLv3 !TLSv1 !TLSv1.1 ssl_min_protocol = TLSv1.2
As you can see, I clearly do not want to use TLS before v1.2. I think this is not unreasonable in the year 2021.
Now, after the changes I ran Kali (I use it to verify the results of my experiments) and - this is a mailing list, so no screenshots: It says:
SSL/TLS Deprecated TLS v1.0 and TLS v1.1 Detection. I get this for the ports 143, 110, 993 and 995.
I thought I had done everything one could to disable old TLS-Versions. What am I doing wrong?
Yours sincerely Stefan Schumacher
Hi!
First of all, 2.3.4.1 is bit old, and has no proper support for TLSv1.3, which is supported better on a later version. Now, I installed 2.3.4.1 from debian 10, and tested with testssl.sh and got
SSLv2 not offered (OK) SSLv3 not offered (OK) TLS 1 not offered TLS 1.1 not offered TLS 1.2 offered (OK) TLS 1.3 offered (OK): final NPN/SPDY not offered ALPN/HTTP2 not offered
TLSv1.2 (no server order, thus listed by strength) xc030 ECDHE-RSA-AES256-GCM-SHA384 ECDH 521 AESGCM 256 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 xc028 ECDHE-RSA-AES256-SHA384 ECDH 521 AES 256 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 xc014 ECDHE-RSA-AES256-SHA ECDH 521 AES 256 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA xcca8 ECDHE-RSA-CHACHA20-POLY1305 ECDH 521 ChaCha20 256 TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 xc077 ECDHE-RSA-CAMELLIA256-SHA384 ECDH 521 Camellia 256 TLS_ECDHE_RSA_WITH_CAMELLIA_256_CBC_SHA384 xc061 ECDHE-ARIA256-GCM-SHA384 ECDH 521 ARIAGCM 256 TLS_ECDHE_RSA_WITH_ARIA_256_GCM_SHA384 xc02f ECDHE-RSA-AES128-GCM-SHA256 ECDH 521 AESGCM 128 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 xc027 ECDHE-RSA-AES128-SHA256 ECDH 521 AES 128 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 xc013 ECDHE-RSA-AES128-SHA ECDH 521 AES 128 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA xc076 ECDHE-RSA-CAMELLIA128-SHA256 ECDH 521 Camellia 128 TLS_ECDHE_RSA_WITH_CAMELLIA_128_CBC_SHA256 xc060 ECDHE-ARIA128-GCM-SHA256 ECDH 521 ARIAGCM 128 TLS_ECDHE_RSA_WITH_ARIA_128_GCM_SHA256 TLSv1.3 (no server order, thus listed by strength) x1302 TLS_AES_256_GCM_SHA384 ECDH 253 AESGCM 256 TLS_AES_256_GCM_SHA384 x1303 TLS_CHACHA20_POLY1305_SHA256 ECDH 253 ChaCha20 256 TLS_CHACHA20_POLY1305_SHA256 x1301 TLS_AES_128_GCM_SHA256 ECDH 253 AESGCM 128 TLS_AES_128_GCM_SHA256
I used:
listen = *
mail_attribute_dict = file:%h/Mail/dovecot-attributes
mail_gid = vmail
mail_home = /home/vmail/%Lu
mail_location = sdbox:~/Mail
mail_uid = vmail
passdb {
args = password=#hidden_use-P_to_show#
driver = static
}
protocols = imap
ssl_cert = Aki
Aki
On 15/07/2021 16:51 Stefan Schumacher s.schumacher@consulting1x1.com wrote:
Hi Aki,
Where do I get testssh.sl? If the script is of your design could you mail it to me?
Yours Stefan
Von: Aki Tuomi aki.tuomi@open-xchange.com Gesendet: Mittwoch, 14. Juli 2021 19:34 An: Stefan Schumacher s.schumacher@consulting1x1.com; dovecot@dovecot.org dovecot@dovecot.org Betreff: Re: TLS Security
On 14/07/2021 17:55 Stefan Schumacher s.schumacher@consulting1x1.com wrote:
Hi,
I wish to build a new secure email server. It seems I am on the right way – at least I get no more error messages for Postfix – but Dovecot is still making trouble.
I am using Dovecot 1:2.3.4.1-5+deb10u6 and I am using ISPconfig 3.25 to do the rough configuring and nano and whats left of my brain to do the finer details. Lets start with what I added to conf.d/10-ssl.conf
ssl_cert =
ssl_cipher_list = EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:EECDH+aR$ ssl_protocols = !SSLv2 !SSLv3 !TLSv1 !TLSv1.1 ssl_min_protocol = TLSv1.2
As you can see, I clearly do not want to use TLS before v1.2. I think this is not unreasonable in the year 2021.
Now, after the changes I ran Kali (I use it to verify the results of my experiments) and - this is a mailing list, so no screenshots: It says:
SSL/TLS Deprecated TLS v1.0 and TLS v1.1 Detection. I get this for the ports 143, 110, 993 and 995.
I thought I had done everything one could to disable old TLS-Versions. What am I doing wrong?
Yours sincerely Stefan Schumacher
Hi!
First of all, 2.3.4.1 is bit old, and has no proper support for TLSv1.3, which is supported better on a later version. Now, I installed 2.3.4.1 from debian 10, and tested with testssl.sh and got
SSLv2 not offered (OK) SSLv3 not offered (OK) TLS 1 not offered TLS 1.1 not offered TLS 1.2 offered (OK) TLS 1.3 offered (OK): final NPN/SPDY not offered ALPN/HTTP2 not offered
TLSv1.2 (no server order, thus listed by strength) xc030 ECDHE-RSA-AES256-GCM-SHA384 ECDH 521 AESGCM 256 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 xc028 ECDHE-RSA-AES256-SHA384 ECDH 521 AES 256 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 xc014 ECDHE-RSA-AES256-SHA ECDH 521 AES 256 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA xcca8 ECDHE-RSA-CHACHA20-POLY1305 ECDH 521 ChaCha20 256 TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 xc077 ECDHE-RSA-CAMELLIA256-SHA384 ECDH 521 Camellia 256 TLS_ECDHE_RSA_WITH_CAMELLIA_256_CBC_SHA384 xc061 ECDHE-ARIA256-GCM-SHA384 ECDH 521 ARIAGCM 256 TLS_ECDHE_RSA_WITH_ARIA_256_GCM_SHA384 xc02f ECDHE-RSA-AES128-GCM-SHA256 ECDH 521 AESGCM 128 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 xc027 ECDHE-RSA-AES128-SHA256 ECDH 521 AES 128 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 xc013 ECDHE-RSA-AES128-SHA ECDH 521 AES 128 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA xc076 ECDHE-RSA-CAMELLIA128-SHA256 ECDH 521 Camellia 128 TLS_ECDHE_RSA_WITH_CAMELLIA_128_CBC_SHA256 xc060 ECDHE-ARIA128-GCM-SHA256 ECDH 521 ARIAGCM 128 TLS_ECDHE_RSA_WITH_ARIA_128_GCM_SHA256 TLSv1.3 (no server order, thus listed by strength) x1302 TLS_AES_256_GCM_SHA384 ECDH 253 AESGCM 256 TLS_AES_256_GCM_SHA384 x1303 TLS_CHACHA20_POLY1305_SHA256 ECDH 253 ChaCha20 256 TLS_CHACHA20_POLY1305_SHA256 x1301 TLS_AES_128_GCM_SHA256 ECDH 253 AESGCM 128 TLS_AES_128_GCM_SHA256
I used:
listen = * mail_attribute_dict = file:%h/Mail/dovecot-attributes mail_gid = vmail mail_home = /home/vmail/%Lu mail_location = sdbox:~/Mail mail_uid = vmail passdb { args = password=#hidden_use-P_to_show# driver = static } protocols = imap ssl_cert =
Aki
participants (4)
-
Aki Tuomi
-
justina colmena ~biz
-
Plutocrat
-
Stefan Schumacher