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© Virtual Access 2018
GW2020 Series User Manual
Issue: 2.1
Page 265 of 423
28
Configuring firewall
The firewall itself is not required. It is a set of scripts which configure Netfilter. If
preferred, you can use Netfilter directly to achieve the desired firewall behaviour.
Note: the UCI firewall exists to simplify the configuration of Netfilter for many scenarios,
without requiring the knowledge to deal with the complexity of Netfilter.
The firewall configuration consists of several zones covering one or more interfaces.
Permitted traffic flow between the zones is controlled by forwardings. Each zone can
include multiple rules and redirects (port forwarding rules).
The Netfilter system is a chained processing filter where packets pass through various
rules. The first rule that matches is executed often leading to another rule-chain until a
packet hits either ACCEPT or DROP/REJECT.
Accepted packets pass through the firewall. Dropped packets are prohibited from
passing. Rejected packets are also prohibited but an ICMP message is returned to the
source host.
A minimal firewall configuration for a router usually consists of one 'defaults' section, at
least two 'zones' (LAN and WAN) and one forwarding to allow traffic from LAN to WAN.
Other sections that exist are 'redirects', 'rules' and 'includes'.
28.1
Configuration package used
Package
Sections
firewall
28.2
Configuring firewall using the web interface
In the top menu, select Network -> Firewall. The Firewall page appears. It is divided
into four sections:
Section
Description
General Zone Settings
Defines the firewall zones, both global and specific.
Port Forwards
Port Forwards are also known as Redirects. This section creates the redirects
using DNAT (Destination Network Address Translation) with Netfilter.
Traffic Rules
Defines rules to allow or restrict access to specific ports, hosts or protocols.
28.2.1
Firewall: zone settings
The Zone settings section is divided into two:
Section
Description
General Settings
Defines the global firewall settings that do not belong to any specific zones.
Zones
The zones section groups one or more interfaces and serves as a source or
destination for forwardings, rules and redirects. Masquerading (NAT) of outgoing
traffic is controlled on a per-zone basis.