明文传输:

yum install -y dovecot dovecot-devel clucene-core

(/etc/dovecot/dovecot.conf)

更改电子邮件协议protocols = iamp pop3 lmtp ##开启验证类型

 24 protocols = imap pop3 lmtp

添加disable_plaintext_auth = no 开启允许使用明文传输

 25 disable_plaintext_auth = no

login_trusted_networks设置允许来自指定网段的主机使用

 49 login_trusted_networks = 10.4.220.0/24

配置邮箱位置 #在子配置文件中(/etc/dovecot/conf.d/10-mail.conf)

24     mail_location = maildir:~/Maildir

加密传输:

#生成SSL密钥文件(自签名X509证书)；

yum install openssl openssl-perl

openssl genrsa -des3 -out server.key 1024

openssl req -new -key server.key -out server.csr

openssl x509 -req -days 365 -sha256 -in server.csr -signkey server.key

cp -a * /etc/pki/CA/certs

修改Postfix配置文件 在文件中修改 启用SSL加密参数

(/etc/postfix/main.cf)

echo smtpd_use_tls = yes

smtpd_tls_cert_file = /etc/pki/CA/certs/servernew.crt

smtpd_tls_key_file = /etc/pki/CA/certs/server.key

smtpd_tls_session_cache_database = btree:/etc/postfix/smtpd_scache

(/etc/postfix/master.cf)

smtps inet n – n – – smtpd

-o smtpd_tls_wrappermode=yes

#openssl genrsa -out :key.pem

openssl req -new -key key.pem -out csr.pem

openssl x509 -req -days 365 -in csr.pem -signkey key.pem -out cert.pem

cat key.pem cert.pem > dovecot.cert.pem

修改dovecot额配置文件指定开启SSl模式 指定证书位置

(/etc/dovecot/conf.d/10-ssl.conf)

ssl_cert = </etc/pki/CA/certs/dovecot.pem

ssl_key = </etc/pki/CA/private/dovecot.pem

防火墙放通SMTPS POP3 IMAPS端口 465;  993;  995; /tcp

postfix与dovecot使用独立的证书(这种通常使用于大型企业环境  需要确保每个服务配置正确的证书和私钥)

postfix:

openssl genrsa -out server.key 2048

openssl req -new -key postfix.key -out postfix.csr

openssl x509 -req -days 365 -in postfix.csr -signkey postfix.key -out postfix.crt

dovecot:

openssl genpkey -algorithm RSA -out dovecot.key -pkeyopt rsa_keygen_bits:2048

openssl req -new -key dovecot.key -out dovecot.csr

openssl x509 -req -days 365 -in dovecot.csr -signkey dovecot.key -out dovecot.crt

创建用户mailx mail2

useradd mailx;useradd mail2

echo Pass-1234|passwd –stdin mailx

echo Pass-1234|passwd –stdin mail2

echo “all: mailx,mail2” >> /etc/aliases

用户尝试发送邮件

yum install telnet

telnet mail.skills.lan 25