ufw

Uncomplicated Firewall — simple iptables frontend for Ubuntu/Debian.

high risk

interactive breakdown — edit the command and press Explain
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⚠ Risks & cautions
Safer / dry-run alternatives
ufw allow OpenSSH && ufw status verboseAllow SSH first, then verify.
What it does

ufw (Uncomplicated Firewall) provides a simpler interface to iptables, widely used on Ubuntu and Debian systems. Rules are written in plain English (allow/deny + port/service). Always allow SSH before enabling ufw to avoid self-lockout.

Examples
ufw status verboseShow all rules and status · explain & risk-check →
ufw allow sshAllow SSH (do this BEFORE enabling ufw) · explain & risk-check →
ufw allow 443/tcpAllow HTTPS · explain & risk-check →
ufw deny from 203.0.113.5Block a specific IP · explain & risk-check →
ufw enableEnable firewall (apply all rules) · explain & risk-check →
ufw delete allow 80/tcpRemove a specific rule · explain & risk-check →
ufw resetReset all rules to default (disables ufw) · explain & risk-check →
Pro tip

On fresh Ubuntu servers, run `ufw allow ssh && ufw allow 443/tcp && ufw enable` in a single SSH session — if SSH fails, the session stays open and you can fix it.

Related
firewalld iptables ss
Open the full explainer →More in Networking

Reference text is hand-written and may be incomplete — check man ufw for your version. Test destructive commands on a non-production system first.