Build firewall rules visually for iptables, nftables, and cloud security groups. Export as commands or JSON configs.
The Firewall Rule Builder turns a rule described in plain fields - protocol, source address, ports, action - into ready-to-run firewall syntax. Pick a target, fill in the match conditions, and it renders the rule as an iptables command, an nftables rule, or a cloud security group entry, plus a JSON form of the same rule for config management. The surprise most users hit is rule ordering: the builder shows each rule in isolation, but iptables and nftables evaluate rules top-down and first match wins, so a generated command only does what you expect if you insert it at the right position in the chain.
A concrete input and expected output from the current implementation.
Input
Allow inbound SSH: protocol TCP, destination port 22, source 203.0.113.10, action ACCEPT.
Expected output
iptables -A INPUT -s 203.0.113.10 -p tcp --dport 22 -j ACCEPT
Each field maps directly to an iptables clause: -s from the source, -p from the protocol, --dport from the destination port, -j from the action, appended to the INPUT chain because the rule is inbound. The same fields render as the nftables rule 'nft add rule inet filter input ip saddr 203.0.113.10 tcp dport 22 accept' when that target is selected, and as JSON for config-driven workflows.
One rule is a set of match fields - protocol, source address or CIDR, destination port or range, interface, direction - plus an action. The builder recombines those fields into the syntax of the chosen target: -s/-p/--dport clauses for iptables, positional expressions for nftables, protocol-plus-CIDR entries for security groups. The generated text is literal; it is not applied to any system.
An inbound rule lands in the INPUT chain (iptables) or an input-hook chain (nftables); outbound becomes OUTPUT, forwarded traffic becomes FORWARD. Cloud security groups instead get an ingress or egress entry. The exported JSON mirrors the structured fields, which matters if you manage rules through configuration files or infrastructure-as-code rather than shell commands.
The page only builds text; it runs nothing and cannot see your machine. You copy the command and run it yourself with sudo, then verify with iptables -L -n or nft list ruleset. Also note the rules are not persistent: a reboot restores the previous ruleset unless you save it with iptables-save or your distribution's firewall tool.
No. The builder is one-way: it produces syntax from the fields you enter and cannot read your live firewall, which would require root access a browser page cannot have. To modify existing rules, re-enter them in the builder or edit your rules file directly, keeping a backup of the current ruleset before reloading it.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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