Introduction
UFW, or Uncomplicated Firewall, is an interface to iptables that is geared towards simplifying the process of configuring a firewall. While iptables is a solid and flexible tool, it can be difficult for beginners to learn how to use it to properly configure a firewall. If you’re looking to get started securing your network, and you’re not sure which tool to use, UFW may be the right choice for you.
This tutorial will show you how to set up a firewall with UFW on Ubuntu 14.04.
Prerequisites
Before you start using this tutorial, you should have a separate, non-root superuser account—a user with sudo privileges—set up on your Ubuntu server. You can learn how to do this by completing at least steps 1-3 in the Initial Server Setup with Ubuntu 14.04 tutorial.
UFW is installed by default on Ubuntu. If it has been uninstalled for some reason, you can install it with apt-get:
sudo apt-get install ufw
Using IPv6 with UFW
If your Ubuntu server has IPv6 enabled, ensure that UFW is configured to support IPv6 so that it will manage firewall rules for IPv6 in addition to IPv4. To do this, open the UFW configuration with your favorite editor. We’ll use nano:
sudo nano /etc/default/ufw
Then make sure the value of « IPV6 » is to equal « yes ». It should look like this:
/etc/default/ufw excerpt
...
IPV6=yes
...
Save and quit. Hit Ctrl-X to exit the file, then Y to save the changes that you made, then ENTER to confirm the file name.
When UFW is enabled, it will be configured to write both IPv4 and IPv6 firewall rules.
This tutorial is written with IPv4 in mind, but will work fine for IPv6 as long as you enable it.
Check UFW Status and Rules
At any time, you can check the status of UFW with this command:
sudo ufw status verbose
By default, UFW is disabled so you should see something like this:
Output:
Status: inactive
If UFW is active, the output will say that it’s active, and it will list any rules that are set. For example, if the firewall is set to allow SSH (port 22) connections from anywhere, the output might look something like this:
Output:
Status: active
Logging: on (low)
Default: deny (incoming), allow (outgoing), disabled (routed)
New profiles: skip
To Action From
-- ------ ----
22/tcp ALLOW IN Anywhere
As such, use the status command if you ever need to check how UFW has configured the firewall.
Before enabling UFW, we will want to ensure that your firewall is configured to allow you to connect via SSH. Let’s start with setting the default policies.
Lire la suite…
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