🌷 Esparzo 🌷 : What is a UFW in ubuntu ?

UFW (Uncomplicated Firewall) is a user-friendly frontend for managing iptables/nftables firewall rules in Linux systems like Ubuntu and Debian.

Below is a structured reference to the most common UFW commands. Most configuration changes require sudo privileges.

1. General Management & Status

These commands let you control the firewall state and check current active rulesets.

Check status:
```
sudo ufw status
```
Check detailed status (shows logging levels and default policies):
```
sudo ufw status verbose
```
Enable the firewall (starts on system boot):
```
sudo ufw enable
```
Disable the firewall:
```
sudo ufw disable
```
Reload the firewall (applies modifications to configuration files):
```
sudo ufw reload
```
Reset the firewall (deletes all rules and restores defaults):
```
sudo ufw reset
```

2. Default Policies

Setting global policies determines how UFW treats traffic that doesn't match any specific rule. The standard recommended baseline is to block incoming and allow outgoing:

Block all incoming traffic by default:
```
sudo ufw default deny incoming
```
Allow all outgoing traffic by default:
```
sudo ufw default allow outgoing
```

3. Managing Port & Protocol Rules

You can open or close ports using service names (defined in /etc/services) or explicit port numbers.

Allow a service by name (e.g., SSH):
```
sudo ufw allow ssh
```
Allow a specific port (both TCP and UDP):
```
sudo ufw allow 80
```
Allow a specific port and protocol (recommended):
```
sudo ufw allow 443/tcp
```
Allow a specific port range (protocol required):
```
sudo ufw allow 40000:50000/tcp
```
Deny traffic on a port:
```
sudo ufw deny 25
```
Rate limit connections (useful for preventing brute force on SSH; caps at 6 connections per 30 seconds from a single IP):
```
sudo ufw limit 22/tcp
```

4. IP-Based Filtering

To handle connections originating from specific network locations, use these commands:

Allow all traffic from a specific IP address:
```
sudo ufw allow from 203.0.113.10
```
Block all traffic from a specific IP address:
```
sudo ufw deny from 203.0.113.10
```

Allow an IP address to access a specific port:

sudo ufw allow from 203.0.113.10 to any port 22

Allow an entire subnet (CIDR notation) to access a specific port:
```
sudo ufw allow from 10.0.0.0/24 to any port 3306
```

5. Deleting Rules

There are two primary methods to remove rules you no longer need:

Delete by original specification: Duplicate the exact rule you added but prepend the word delete.
```
sudo ufw delete allow 80/tcp
```
Delete by line number (Easiest for clean-up): First, list rules with assigned numbers:
```
sudo ufw status numbered
```
Then, delete using the corresponding index:
```
sudo ufw delete 3
```

6. Application Profiles

Many packages (like Nginx, Apache, or OpenSSH) install profiles inside UFW to simplify rule management.

List available application profiles:
```
sudo ufw app list
```
View details about a specific profile:
```
sudo ufw app info "Nginx Full"
```
Allow an application profile:
```
sudo ufw allow "OpenSSH"
```

7. Logging Options

Turn logging on/off:

sudo ufw logging on
sudo ufw logging off

Change log level granularity (low, medium, high, full):
```
sudo ufw logging medium
```

Important Safety Warning: If you are configuring a remote server over SSH, always execute sudo ufw allow ssh or sudo ufw allow 22/tcp before running sudo ufw enable. Failing to do so will immediately lock you out of your server.

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Friday, 10 July 2026

What is a UFW in ubuntu ?