Uncomplicated firewall (ufw) is a simple frontend for iptables and is available in [community]. The next two sections are simply high-level explanations and examples. Users are encouraged to consult the Ubuntu Firewall Help page for additional details.
Template:Package Official can be installed from [community]. If you don't already have iptables installed, it will be pulled in as a dependency.
You need to include ufw in your daemons array in rc.conf, ideally before bringing up your network interfaces. Do not include the iptables daemon because it simply loads an iptables ruleset from /etc/iptables/.
A very simplistic configuration which will deny all by default, allow any protocol from inside a 192.168.0.1-192.168.0.255 LAN, and allow incoming Deluge and SSH traffic from anywhere:
# ufw default deny # ufw allow from 192.168.0.0/24 # ufw allow Deluge # ufw allow SSH
The next line is only need once the first time you install the package. From there on out, either put ufw in your daemons array in rc.conf or control it via the standard rc.d script (i.e. rc.d start ufw):
# ufw enable
Finally, query the rules being applied via the status command:
# ufw status
Status: active To Action From -- ------ ---- Anywhere ALLOW 192.168.0.0/24 Deluge ALLOW Anywhere SSH ALLOW Anywhere
Adding Other Applications
The PKG comes with some defaults based on the default ports of many common daemons and programs. Inspect the options by looking in the /etc/ufw/applications.d directory or by listing them in the program itself:
# ufw app list
If users are running any of the applications on a non-standard port, it is recommended to simply make Template:Filename containing the needed data using the defaults as a guide.
Example, deluge with custom tcp ports that range from 20202-20205:
[Deluge-my] title=Deluge description=Deluge BitTorrent client ports=20202:20205/tcp
Should you require to define both tcp and udp ports for the same application, simply separate them with a pipe as shown: this app opens tcp ports 10000-10002 and udp port 10003
One can also use a comma to define ports if a range is not desired. This example opens tcp ports 10000-10002 (inclusive) and udp ports 10003 and 10009
Drawing on the Deluge/Deluge-my example above, the following will remove the standard Deluge rules and replace them with the Deluge-my rules from the above example:
# ufw delete allow Deluge # ufw allow Deluge-my
Query the result via the status command:
# ufw status
Status: active To Action From -- ------ ---- Anywhere ALLOW 192.168.0.0/24 SSH ALLOW Anywhere Deluge-my ALLOW Anywhere
Rate Limiting with ufw
ufw has the ability to deny connections from an IP address that has attempted to initiate 6 or more connections in the last 30 seconds. Users should consider using this option for services such as sshd.
Using the above basic configuration, to enable rate limiting we would simply replace the allow parameter with the limit parameter. The new rule will then replace the previous.
# ufw limit ssh Rule updated # ufw status
Status: active To Action From -- ------ ---- Anywhere ALLOW 192.168.0.0/24 SSH LIMIT Anywhere Deluge-my ALLOW Anywhere