Topic: firewalld
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Firewalld and nftables rules for NFS, Samba, NTP, DNS and DHCP: exactly which ports to open
A reference for the exact ports these infrastructure services need — NFS4 TCP 2049, Samba TCP 445 (139 and UDP 137/138 only for NetBIOS), DNS TCP+UDP 53, DHCP UDP 67, NTP UDP 123 — with firewalld's predefined services, the equivalent nftables dport syntax, and why a UDP nmap/nc probe is a weak test compared with the real client.
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Managing firewalld zones and rules without locking yourself out over SSH
firewalld separates a running configuration from a permanent one, and a plain firewall-cmd change is lost on the next reload unless made permanent. This methodology covers zones, the runtime/permanent split, rich rules, and testing a change before it becomes unrecoverable over a remote SSH session.
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Host firewalls compared: nftables, firewalld, ufw, Windows Defender Firewall, pf and ipfw
Listing rules, opening a port, making the change survive a reboot, and doing it without locking yourself out over SSH or RDP — the same four tasks across nftables, firewalld, ufw, Windows Defender Firewall, and the BSD pf and ipfw packet filters.
Machine-readable: JSON