Allow a port through the firewall with ufw

Add a UFW rule to permit inbound traffic on a TCP or UDP port, such as SSH on port 22.

LinuxnetworksecurityHigh risk

Run sudo ufw allow 22/tcp to permit inbound SSH, then check the rule with sudo ufw status verbose.

01Command

Command

$ sudo ufw allow 22/tcp

02What it does

Rules accept port/protocol (80/tcp), service names from /etc/services (ufw allow ssh), or app profiles (ufw allow 'Nginx Full'); omit the protocol to allow both TCP and UDP. By default an allow rule opens the port on all interfaces — restrict it to a subnet with ufw allow from 192.168.1.0/24 to any port 22. Order matters: first matching rule wins, and ufw status numbered plus ufw delete <n> lets you remove by position. Verify with sudo ufw status verbose; only rules while ufw is enabled are enforced.

03Risk

RiskHigh risk

RequirementsUFW installed and enabled (sudo ufw enable); on Ubuntu it is preinstalled but inactive by default

!Warning: Enable UFW only after adding a rule for your active SSH session — on a remote server, enabling a firewall without an allow rule locks you out immediately.

04Undo

Undo

$ sudo ufw delete allow 22/tcp

05Sources

UncomplicatedFirewall - Ubuntu Wiki
Ubuntu Wiki · vendor-doc · 2026-09-17
Evidence: The Ubuntu UFW wiki describes enabling the firewall with ufw enable and adding allow rules by port and protocol.
ufw(8) — program for managing a netfilter firewall
Ubuntu manpages · vendor-doc · 2026-09-17
Evidence: The ufw manual documents 'ufw allow' rules with PORT/PROTO syntax such as 22/tcp and matching 'ufw delete allow' to remove them.

Last verified: 2026-09-17 · Category: Security & Privacy

06Related solutions

Show IP addresses in a compact table with `ip -br a`

Linuxifconfignetworktroubleshooting

One command that prints every interface with its state and IPv4/IPv6 addresses in a short table — the modern, memorable replacement for digging through `ifconfig` or the verbose `ip addr` output.

Low risk ✓ 2026-09-17

Create an SSH key pair with ssh-keygen (Ed25519)

LinuxTerminaldevelopersecurity

Generate a modern Ed25519 public/private key pair in ~/.ssh for authenticating to servers and Git platforms without passwords.

Low risk ✓ 2026-09-17

Change file permissions with chmod

LinuxFilesTerminalsecurity

Add or remove read, write, and execute permission for the owner, group, or others using symbolic or octal modes.

Medium risk ✓ 2026-09-17