11.4. Packet filter with Univention Firewall#

Univention Firewall integrates a packet filter based on iptables in Univention Corporate Server.

It permits targeted filtering of undesired services and the protection of computers during installations. Furthermore it provides the basis for complex scenarios such as firewalls and application level gateways. Univention Firewall is included in all UCS installations as standard.

By default all incoming ports are blocked. Every UCS package provides rules, which free up the ports required by the package again.

The configuration is primarily performed via Univention Configuration Registry variables. The definition of this type of packet filter rules is documented in Univention Developer Reference [5].

In addition, the configuration scripts in the /etc/security/packetfilter.d/ directory are listed in alphabetic order. The names of all scripts begin with two digits, which allows a numbered order. The scripts must be marked as executable.

After changing the packet filter settings, the univention-firewall service has to be restarted.

Univention Firewall can be deactivated by setting the Univention Configuration Registry Variable security/packetfilter/disabled to true