问题：用户说C2750在检测脚本中，显示频率为 CPU Cores: 8Cores 1200.000 MHz x86_64 信息中的 1200.000 MHz ，与 2.6GHz 有较大的差距。

尝试：系统是CentOS7，可通过命令：cpupower frequency-set --governor performance 来设置CPU处理器的运行频率为最大值，即 2.6GHz。监测CPU当前的运行频率命令是：watch grep \"cpu MHz\" /proc/cpuinfo

参考：

• https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/power_management_guide/cpufreq_governors#cpufreq_setup
• https://wiki.archlinux.org/index.php/CPU_frequency_scaling_(%E7%AE%80%E4%BD%93%E4%B8%AD%E6%96%87)

需求：在centos8里为eno1网卡批量加192.168.99.3到192.168.99.100的IP地址，掩码是255.255.255.0

尝试：用nmcli批量加，如 for I in $(seq 3 100); do nmcli con mod eno1 +ipv4.addresses 192.168.99.${I}/24; done 之后重载配置内容 nmcli con up eno1

参考：https://forums.centos.org/viewtopic.php?t=55889

问题：centos7 里的 postfix 日志中提示兼容性信息提示。

尝试：原来是将原debian 里的 postfix 配置文件复制到 centos7 中发生的。默认 centos 不使用 chroot 环境，所以将配置文件中的 chroot 列值，从 - 修改为 n 重启 postfix 就可以了。

Nov 19 23:25:44 localhost postfix/master[865]: /etc/postfix/master.cf: line 18: using backwards-compatible default setting chroot=y
Nov 19 23:25:44 localhost postfix/master[865]: /etc/postfix/master.cf: line 26: using backwards-compatible default setting chroot=y
Nov 19 23:25:44 localhost postfix/master[865]: /etc/postfix/master.cf: line 35: using backwards-compatible default setting chroot=y

参考：

• https://serverfault.com/questions/958761/postfix-using-backwards-compatible-ssl-tls-only-mailserver
• https://serverfault.com/questions/655116/postfix-fails-to-send-mail-with-fatal-unknown-service-smtp-tcp

问题：/var/log/maillog 日志中，有dovecot的警告信息，如

Nov 19 23:25:22 localhost dovecot: imap(laile@s)<1100>: Warning: autocreate plugin is deprecated, use mailbox { auto } setting instead

尝试：将dovecot配置文件中的原：

protocol imap {
  mail_plugins = "autocreate"
}

plugin {
  autocreate = Trash
  autocreate2 = Sent
  autosubscribe = Trash
  autosubscribe2 = Sent
}

替换为：

namespace inbox {
  inbox = yes

  mailbox Trash {
    auto = subscribe # autocreate and autosubscribe the Trash mailbox
    special_use = \Trash
  }
  mailbox Sent {
    auto = subscribe # autocreate and autosubscribe the Sent mailbox
    special_use = \Sent
  }
}

参考：https://serverfault.com/questions/763487/dovecot-autocreate-plugin-is-deprecated-use-mailbox-auto-setting

环境：CentOS7

问题：邮箱用户通过imap登录失败，/var/log/maillog 日志中有错误信息：localhost postfix/submission/smtpd[451]: error: unsupported dictionary type: mysql

尝试：yum install postfix-mysql 安装 postfix-mysql 后重启 postfix

参考：https://serverfault.com/questions/622796/postfix-error-unsupported-dictionary-type-mysql