Firewalld Dynamic Firewall Manager

Firewalld is a firewall management tool for Linux operating systems, providing a dynamically managed firewall with support for network and firewall zones, designed to replace the traditional iptables service with a more user-friendly and flexible approach. Originally developed by Thomas Woerner at Red Hat in 2011, firewalld has become the default firewall solution on Fedora, RHEL, CentOS, AlmaLinux, Rocky Linux, and many other Linux distributions. Key features include: zone-based configuration (predefined zones including public, home, internal, trusted, block, drop, dmz, work, and external, each with different trust levels and default rules, plus custom zones for specialized network configurations), runtime and permanent configuration (runtime changes apply immediately without disrupting existing connections, while permanent changes persist across reboots, with automatic migration between the two), service definitions (over 80 predefined services including SSH, HTTP, HTTPS, DNS, FTP, SMTP, NFS, and LDAP, with easy addition of custom service definitions including port, protocol, and module specifications), rich language rules (fine-grained rule syntax for source/destination IP, port, protocol, logging, rate limiting, and action specification beyond simple service allow/deny), D-Bus interface (programmatic control via D-Bus API enabling integration with NetworkManager, libvirt, Podman, and other system services), direct interface (passthrough to underlying nftables or iptables for advanced users requiring raw rules), masquerading and NAT (IP masquerading, port forwarding, and destination NAT for routing and gateway scenarios), ICMP filtering (controlling which ICMP types are accepted or rejected), logging (accept, reject, drop, and all packet logging with configurable log levels), panic mode (emergency mode blocking all network traffic with a single command), and migration from iptables (automatic conversion of existing iptables rules to firewalld configuration).