UFW Cheatsheet
Quick reference for managing firewall rules with UFW on Linux
UFW (Uncomplicated Firewall) is a simple frontend for managing Linux firewall rules. This cheatsheet covers common UFW commands for status checks, allowing and denying traffic, deleting rules, and basic troubleshooting.
Basic Commands
Start with status and firewall state.
| Command | Description |
|---|---|
ufw status | Show firewall status and rules |
ufw status verbose | Show detailed status and defaults |
sudo ufw enable | Enable UFW |
sudo ufw disable | Disable UFW |
sudo ufw reload | Reload rules |
sudo ufw reset | Reset UFW to defaults |
Default Policies
Set default inbound and outbound behavior.
| Command | Description |
|---|---|
sudo ufw default deny incoming | Deny all incoming by default |
sudo ufw default allow outgoing | Allow all outgoing by default |
sudo ufw default deny outgoing | Deny all outgoing by default |
sudo ufw default allow incoming | Allow all incoming (not recommended on servers) |
Allow and Deny Rules
Allow or block traffic by port and protocol.
| Command | Description |
|---|---|
sudo ufw allow 22 | Allow port 22 (TCP and UDP) |
sudo ufw allow 80/tcp | Allow HTTP over TCP |
sudo ufw allow 443/tcp | Allow HTTPS over TCP |
sudo ufw deny 25 | Deny SMTP port 25 |
sudo ufw reject 23 | Reject Telnet connections |
sudo ufw limit 22/tcp | Rate-limit SSH connections |
Rule Management
List, delete, and clean specific rules.
| Command | Description |
|---|---|
sudo ufw status numbered | List rules with numbers |
sudo ufw delete allow 80/tcp | Delete matching rule |
sudo ufw delete 3 | Delete rule by number |
sudo ufw delete deny 25 | Delete a deny rule |
IP-Based Rules
Allow or deny traffic from specific hosts and networks.
| Command | Description |
|---|---|
sudo ufw allow from 203.0.113.10 | Allow all traffic from one IP |
sudo ufw deny from 203.0.113.10 | Block all traffic from one IP |
sudo ufw allow from 203.0.113.10 to any port 22 | Allow SSH from one IP |
sudo ufw allow from 10.0.0.0/24 to any port 3306 | Allow MySQL from a subnet |
sudo ufw deny from 198.51.100.0/24 to any port 22 proto tcp | Deny TCP SSH from subnet |
Application Profiles
Use service profiles from /etc/ufw/applications.d/.
| Command | Description |
|---|---|
sudo ufw app list | List available application profiles |
sudo ufw app info "Nginx Full" | Show ports/protocols for profile |
sudo ufw allow "OpenSSH" | Allow profile rules |
sudo ufw deny "Nginx HTTP" | Deny profile rules |
sudo ufw delete allow "OpenSSH" | Remove allowed profile |
Logging
Control and inspect UFW logging.
| Command | Description |
|---|---|
sudo ufw logging on | Enable logging |
sudo ufw logging off | Disable logging |
sudo ufw logging low | Set low log level |
sudo ufw logging medium | Set medium log level |
sudo ufw logging high | Set high log level |
Common Server Setup
Baseline rules for a web server.
| Command | Description |
|---|---|
sudo ufw default deny incoming | Deny incoming by default |
sudo ufw default allow outgoing | Allow outgoing by default |
sudo ufw allow OpenSSH | Keep SSH access |
sudo ufw allow 80/tcp | Allow HTTP |
sudo ufw allow 443/tcp | Allow HTTPS |
sudo ufw enable | Activate firewall |
sudo ufw status verbose | Verify active rules |
Troubleshooting
Quick checks for common UFW issues.
| Issue | Check |
|---|---|
| SSH access lost after enable | Ensure OpenSSH is allowed before ufw enable |
| Rule did not apply | Run sudo ufw reload and re-check with ufw status numbered |
| Service still unreachable | Confirm service is listening (ss -tulpn) and port/protocol match |
| Rules conflict | Check order with ufw status numbered and delete/re-add as needed |
| UFW not active at boot | Verify service state with systemctl status ufw |
Related Guides
Use these guides for full UFW workflows.
| Guide | Description |
|---|---|
How to Set Up a Firewall with UFW on Ubuntu 20.04 | Full UFW setup on Ubuntu 20.04 |
How to Set Up a Firewall with UFW on Ubuntu 18.04 | UFW setup on Ubuntu 18.04 |
How to Set Up a Firewall with UFW on Debian 10 | UFW setup on Debian 10 |
How to List and Delete UFW Firewall Rules | Rule management and cleanup |