我在向服务器发送邮件时遇到问题，并且有迹象表明存在 TLS 错误（主要来自邮件日志）。我尝试过：
- 确保 postfix / dovecot 可以读取证书（创建新的组“证书”）并进行测试（请参阅下面的 postfix 测试）
- 确保没有 selinux 警报
openssl s_client -connect ${IP}:465失败，但端口 443 可用nmap ${URL}显示端口25,53,80,110,139,143,443,445,993,995全部打开nmap ${LOCALIP}显示端口22,25,80,110,143,443,993,995为打开或465,587关闭。telnet ${IP} 25并运行starttls（失败454 4.7.0 TLS not available due to local problem）- letsencrypt 证书是从正在运行的 haproxy 服务器复制的（全部
/etc/letsencrypt复制） /etc/postfix/*.cf通过将其移动到 *.cf.bak 并重新安装 postfix进行重置
补充笔记：
- 我一直
ansible-hardening在https://github.com/openstack/ansible-hardening服务器上运行。 - 该证书适用于 https 使用（已使用 Firefox 验证）
- 尝试使用 gmail 和 sharklasers 向服务器发送电子邮件
日志：
# cat /var/log/maillog
postfix/postfix-script: starting the Postfix mail system
postfix/master: daemon started -- version 2.10.1, configuration /etc/postfix
postfix/smtpd: warning: No server certs available. TLS won't be enabled
postfix/smtpd: connect from unknown[${IP}]
# postconf -n
alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
broken_sasl_auth_clients = yes
command_directory = /usr/sbin
config_directory = /etc/postfix
daemon_directory = /usr/libexec/postfix
data_directory = /var/lib/postfix
debug_peer_level = 2
debugger_command = PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin ddd $daemon_directory/$process_name $process_id & sleep 5
home_mailbox = Maildir/
html_directory = no
inet_interfaces = all
inet_protocols = all
mail_owner = postfix
mail_spool_directory = /var/spool/mail
mailq_path = /usr/bin/mailq.postfix
manpage_directory = /usr/share/man
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
mydomain = example.com
myhostname = webserver1.example.com
mynetworks = 127.0.0.0/8
myorigin = $mydomain
newaliases_path = /usr/bin/newaliases.postfix
queue_directory = /var/spool/postfix
readme_directory = /usr/share/doc/postfix-2.10.1/README_FILES
sample_directory = /usr/share/doc/postfix-2.10.1/samples
sendmail_path = /usr/sbin/sendmail.postfix
setgid_group = postdrop
smtp_tls_cert_file = /etc/letsencrypt/live/example.com/fullchain.pem
smtp_tls_key_file = /etc/letsencrypt/live/example.com/privkey.pem
smtp_tls_note_starttls_offer = yes
smtp_tls_security_level = may
smtpd_client_restrictions = permit_mynetworks, reject
smtpd_recipient_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination
smtpd_sasl_auth_enable = yes
smtpd_sasl_local_domain =
smtpd_sasl_path = private/auth
smtpd_sasl_security_options = noanonymous
smtpd_sasl_type = dovecot
smtpd_tls_loglevel = 2
smtpd_tls_received_header = yes
smtpd_tls_security_level = may
smtpd_tls_session_cache_timeout = 3600s
tls_random_source = dev:/dev/urandom
unknown_local_recipient_reject_code = 550
# doveconf -n
# 2.2.10: /etc/dovecot/dovecot.conf
# OS: Linux 3.10.0-693.21.1.el7.x86_64 x86_64 CentOS Linux release 7.4.1708 (Core) xfs
auth_mechanisms = plain login
first_valid_uid = 1000
mail_location = maildir:/var/spool/mail/%u
mbox_write_locks = fcntl
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 {
driver = pam
}
service auth {
unix_listener /var/spool/postfix/private/auth {
group = postfix
mode = 0666
user = postfix
}
}
ssl = required
ssl_cert = </etc/letsencrypt/live/example.com/fullchain.pem
ssl_key = </etc/letsencrypt/live/example.com/privkey.pem
userdb {
driver = passwd
}
# # Could replace cat/etc/postfix/main.cf with postconf -n
# sudo -u postfix cat $(cat /etc/postfix/main.cf | grep -i smtp_tls_cert_file | cut --delimiter="=" --fields=2)
-----BEGIN CERTIFICATE-----
...key text...
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
...key text...
-----END CERTIFICATE-----
# sudo -u postfix cat $(cat /etc/postfix/main.cf | grep -i smtp_tls_key_file | cut --delimiter="=" --fields=2)
-----BEGIN PRIVATE KEY-----
...private key text...
-----END PRIVATE KEY-----
# sealert -a /var/log/audit/audit.log
100% done
found 0 alerts in /var/log/audit/audit.log
两个 openssl 命令都给出了有效等效的响应（端口 443 有不同的响应，并且可以工作）。
$ openssl s_client -starttls smtp -connect ${IP}:587
$ openssl s_client -starttls smtp -connect ${IP/URL}:465
CONNECTED(00000003)
140495880024000:error:1408F10B:SSL routines:ssl3_get_record:wrong version number:ssl/record/ssl3_record.c:252:
---
no peer certificate available
---
No client certificate CA names sent
---
SSL handshake has read 5 bytes and written 176 bytes
Verification: OK
---
New, (NONE), Cipher is (NONE)
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
SSL-Session:
Protocol : TLSv1.2
Cipher : 0000
Session-ID:
Session-ID-ctx:
Master-Key:
PSK identity: None
PSK identity hint: None
SRP username: None
Start Time: 1520878163
Timeout : 7200 (sec)
Verify return code: 0 (ok)
Extended master secret: no
---
$ telnet ${IP} 25
Trying ${IP}...
Connected to ${IP}.
Escape character is '^]'.
220 webserver1.example.com ESMTP Postfix
ehlo localhost
250-webserver1.example.com
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-STARTTLS
250-AUTH PLAIN LOGIN
250-AUTH=PLAIN LOGIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
starttls
454 4.7.0 TLS not available due to local problem
答案1
smtp_tls_cert尝试将和的配置更改smtp_tls_key为以下内容：
smtpd_tls_cert_file = /etc/letsencrypt/live/example.com/fullchain.pem
smtpd_tls_key_file = /etc/letsencrypt/live/example.com/privkey.pem
注意dsmtpd