linux security

linux firewall

iptables

Allow port 80 through the firewall: sudo iptables -A INPUT -ptcp --dport 80-j ACCEPT
Check whether the firewall rules take effect:sudo iptables -L -n | grep 80

firewalld

1. firewalld basic commands
   to start the firewall: sudo systemctl start firewalld
   Check firewall status: sudo systemctl status firewalld
   Stop Firewall: sudo systemctl disable firewalld
   Disable Firewall:sudo systemctl stop firewalld
2. firewalld-cmd
   View Version: sudo firewall-cmd --version
   View help: sudo firewall-cmd --help
   display status: sudo firewall-cmd --state
   View all open ports: sudo firewall-cmd --zone=public --list-ports
   updating the firewall rules: sudo firewall-cmd --reload
   viewing area information: sudofirewall-cmd --get-active-zones
   View the specified interface belongs: sudo firewall-cmd --get-zone-of-interface=eth0
   to reject all packages: sudofi rewall-cmd --panic-on
   unblock status: sudo firewall-cmd --panic-off
   Check whether to reject:sudo firewall-cmd --query-panic
3. Firewall port handling
   Add: sudo firewall-cmd --zone=public --add-port=80/tcp --permanent(-permanent permanent, this argument does not fail after the restart)
   reload: sudo firewall-cmd --reload
   View: sudo firewall-cmd --zone= public --query-port=80/tcp
   Delete:sudo firewall-cmd --zone= public --remove-port=80/tcp --permanent