yum源：https://www.cnblogs.com/guanbin-529/p/11980400.html

163源：http://mirrors.163.com/centos/7/os/x86_64/Packages/

安装mysql：https://blog.csdn.net/qq_36582604/article/details/80526287

centos7-tomcat安装配置：https://blog.csdn.net/l568646976/article/details/92099264

远程文件SCP问题：https://jingyan.baidu.com/article/14bd256e1f20dffb6d2612c0.html

远程桌面：https://blog.csdn.net/u014296316/article/details/88257614

xshell密钥登入：https://blog.csdn.net/yuexiazhufeng/article/details/75349724
查看防火墙的状态的命令为：sudo systemctl status firewalld
打开防火墙的方式有两种，一种是打开后重启会恢复回原来的状态，命令为：
sudo systemctl start firewalld；另一种是打开后重启不会恢复到原来的状态，命令为：
sudo systemctl enable firewalld，这种方式输入命令后要重启系统才会生效。
关闭防火墙的方式也有两种，和打开相对应，命令分别为
sudo systemctl stop firewalld
sudo systemctl disable firewalld

获取公网IP地址：curl http://metadata.tencentyun.com/meta-data/public-ipv4

防火墙问题：https://blog.csdn.net/centose/article/details/96975849

CentOS 7.0默认使用的是firewall作为防火墙，之前版本是使用iptables。

1.设置firewall开机启动

systemctl enable firewalld

2.禁止firewall开机启动

systemctl disable firewalld

  1. 之前在本地的CentOS虚拟机上配置 Samba 服务器没有遇到过这种问题, 
  2. 刚才在我的阿里云服务器上配置Samba上下文时, 报出了这个错误
  4. chcon -t samba_share_t /home/suozhiyuan/
  6. chcon: can't apply partial context to unlabeled file '/home/suozhiyuan/'
  10. 找了很久的资料, 发现问题是出在 selinux 放火墙上, 这个防火墙的配置文件为 /etc/selinux/config 
  12. 配置内容:
  14. 原来是关闭: SELINUX=disabled
  15. 改成打开:　 SELINUX=enforcing
  16. 复制代码
  17. # This file controls the state of SELinux on the system.
  18. # SELINUX= can take one of these three values:
  19. #     enforcing - SELinux security policy is enforced.
  20. #     permissive - SELinux prints warnings instead of enforcing.
  21. #     disabled - No SELinux policy is loaded.
  22. #改成
  23. SELINUX=enforcing
  24. # SELINUXTYPE= can take one of these three values:
  25. #     targeted - Targeted processes are protected,
  26. #     minimum - Modification of targeted policy. Only selected processes are protected.
  27. #     mls - Multi Level Security protection.
  28. SELINUXTYPE=targeted