ssl_min_protocol appears to be ignored?

12 Apr 2022


      Hi, I'm trying to enable TLS1.0 support for an old client. Per dovecot -n
# 2.3.7.2 (3c910f64b): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.5.7.2 ()
# OS: Linux 5.4.0-107-generic x86_64 Ubuntu 20.04.4 LTS ext4
# Hostname:
In 10-ssl.conf, I have set
ssl_min_protocol = TLSv1
(It doesn't show in dovecot -n, I suspect because it's equal to default
value?) I restarted dovecot with systemctl. Then, from another machine,
openssl s_client -connect zeserver.com:993 -tls1
fails with this output:
CONNECTED(00000003)
140166917489984:error:141E70BF:SSL
routines:tls_construct_client_hello:no protocols
available:../ssl/statem/statem_clnt.c:1112:
no peer certificate available
No client certificate CA names sent
SSL handshake has read 0 bytes and written 7 bytes
Verification: OK
New, (NONE), Cipher is (NONE)
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
Early data was not sent
Verify return code: 0 (ok)
The same command with -tls1_2 works as intended (certificate printing,
imap prompt).
Am I forgetting something somewhere, or is this an actual bug?

ssl_min_protocol appears to be ignored?

Myriam Luce

CONNECTED(00000003) 140166917489984:error:141E70BF:SSL routines:tls_construct_client_hello:no protocols available:../ssl/statem/statem_clnt.c:1112:

no peer certificate available

No client certificate CA names sent

SSL handshake has read 0 bytes and written 7 bytes Verification: OK

New, (NONE), Cipher is (NONE) Secure Renegotiation IS NOT supported Compression: NONE Expansion: NONE No ALPN negotiated Early data was not sent Verify return code: 0 (ok)