=== CentOS 7+ 网络、Daemon 相关命令 ===
包含了centos system 中 firewalld, port occupation, systemd service management 相关常用命令。
1. firewalld
`firewall-cmd --permanent --add-port=100/tcp ` # open specific port
`firewall-cmd --permanent --add-port=200-300/tcp`
`firewall-cmd --permanent --add-service=http` # open port for service
`firewall-cmd --reload` # take changes into effect
`firewall-cmd --list-ports` # check the ports opened.
`firewall-cmd --list-services` # check the service
` iptables-save` # check all currently applied rules
2. port
netstat -tlunp # display all ports opened in host
lsof -i # list the network open ports
netstat -lptu # the process that owns them
netstat -tulpn # You can add " | grep "kw1|kw2|kw3' " for keywords grep
3. daemon 守护与开机（开机启动可用）
vim /etc/rc.d/rc.local # edit script in this file for script running at boot
vim ~.bash_profile # exe script at log on. and ~.bash_logout for log out.
shutdown -r now
systemctl reboot # Reboot to verify scripts launching during system boot
4. systemd（开机启动可用）
vim /etc/systemd/system/sample.service
[Unit]
Description=Description for sample script goes here
After=network.target
[Service]
Type=simple
ExecStart=/var/tmp/test_script.sh
TimeoutStartSec=0
[Install]
WantedBy=default.target
systemctl daemon-reload
systemctl enable sample.service
systemctl start sample.service
systemctl list-unit-files | grep enabled # list all enabled ones.
systemctl list-unit-files | grep disabled # list all disabled ones.