Overview
UFW is a tool that helps manage firewalls easily on Linux systems. The 'ufw enable' command activates the UFW firewall and ensures that firewall rules are maintained even after system reboots. It's important to verify that appropriate firewall rules are in place before executing this command.
Key Features
- Enables the UFW firewall
- Configures automatic startup on system boot
- Applies default policies (deny incoming, allow outgoing)
Installation
UFW may not be included by default in many Linux distributions, or it might be installed but not enabled. Here's how to install UFW on major distributions.
Debian/Ubuntu
sudo apt update
sudo apt install ufwInstall UFW using the APT package manager.
CentOS/RHEL (EPEL repository required)
sudo yum install epel-release
sudo yum install ufwInstall UFW using the YUM or DNF package manager. You may need to enable the EPEL repository first.
Usage Examples
Demonstrates various ways to enable the UFW firewall.
Enable UFW Firewall
sudo ufw enableEnables the UFW firewall and configures it to start automatically on system reboots. Executing this command applies the firewall with the currently set rules.
Force Enable Without Confirmation Prompt
sudo ufw --force enableImmediately enables UFW without the confirmation prompt that appears during activation. Use this option with caution.
Tips & Precautions
Important considerations before and after enabling the UFW firewall.
Check Rules Before Enabling
Before enabling the firewall, check the currently configured rules to ensure that necessary services (e.g., SSH) are not blocked. Otherwise, you might lose access to your system.
- Check current rules with 'ufw status verbose'
- Allow necessary ports with 'ufw allow [port/service]'
Caution with Remote Access
If you are enabling UFW while connected to the server remotely, you might lose your connection if the SSH port (default 22) is not allowed. You must allow the SSH port first before enabling the firewall.
Default Policies
Default policies applied when UFW is enabled.
- Incoming: Deny all connections by default
- Outgoing: Allow all connections by default