防火墙

如果提示没有该命令，则安装

sudo yum install net-tools

查看端口协议

netstat -anp

[root@hadoop01 ~]# netstat -anp
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      1026/nginx: master  
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      1017/sshd           
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN      1243/master         
tcp        0      0 192.168.205.207:50812   182.89.223.15:80        TIME_WAIT   -                   
tcp        0     36 192.168.205.207:22      192.168.205.1:55545     ESTABLISHED 1539/sshd: root@pts 
tcp6       0      0 :::22                   :::*                    LISTEN      1017/sshd           
tcp6       0      0 ::1:25                  :::*                    LISTEN      1243/master         
udp        0      0 127.0.0.1:323           0.0.0.0:*                           675/chronyd         
udp6       0      0 ::1:323                 :::*                                675/chronyd         
raw6       0      0 :::58                   :::*                    7           711/NetworkManager  
Active UNIX domain sockets (servers and established)
Proto RefCnt Flags       Type       State         I-Node   PID/Program name     Path
unix  2      [ ACC ]     STREAM     LISTENING     9474     1/systemd            /run/systemd/journal/stdout
unix  5      [ ]         DGRAM                    9477     1/systemd            /run/systemd/journal/socket
unix  14     [ ]         DGRAM                    9479     1/systemd            /dev/log

打开端口

firewall-cmd --permanent --add-port=22/tcp

关闭端口

firewall-cmd --permanent --remove-port=22/tcp

重载防火墙

开启或者关闭端口都需要重新载入防火墙，才会生效

firewall-cmd --reload

查看端口是否开放

firewall-cmd --query-port=22/tcp