Netopia 3346N-ENT User Guide (en)

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10-34  Firmware User Guide
Output filter 1: This filter for wards all outgoing traffic to make sure that no outgoing connections from the LAN 
are blocked.
Basic Firewall is suitable for a LAN containing only client hosts that want to access ser vers on the WAN, but not 
for a LAN containing ser vers providing ser vices to clients on the WAN. Basic Firewall’s general strategy is to 
explicitly for ward WAN-originated TCP and UDP traffic to por ts greater than 1023. Por ts lower than 1024 are the 
ser vice origination por ts for various Internet ser vices such as FTP, Telnet, and the World Wide Web (WWW).
A more complicated filter set would be required to provide WAN access to a LAN-based ser ver. See the next 
section, 
 for ways to allow remote hosts to use ser vices provided by ser vers on the 
LAN.
Possible modifications
You can modify the sample filter set Basic Firewall to allow incoming traffic using the examples below. These 
modifications are not intended to be combined. Each modification is to be the only one used with Basic Firewall.
The results of combining filter set modifications can be difficult to predict. It is recommended that you take 
special care if you are making more than one modification to the sample filter set.
Trusted host. To allow unlimited access by a trusted remote host with the IP address a.b.c.d (corresponding to 
a numbered IP address such as 163.176.8.243), inser t the following input filter ahead of the current input 
filter 1:
Enabled: Yes
For ward: Yes
Source IP Address: a.b.c.d
Source IP Address Mask: 255.255.255.255
Dest. IP Address: 0.0.0.0
Dest. IP Address Mask: 0.0.0.0
Protocol Type: 0
Trusted subnet. To allow unlimited access by a trusted remote subnet with subnet address a.b.c.d 
(corresponding to a numbered IP address such as 163.176.8.0) and subnet mask e.f.g.h (corresponding to a 
numbered IP mask such as 255.255.255.0), inser t the following input filter ahead of the current input filter 1:
Enabled: Yes
For ward: Yes
Source IP Address: a.b.c.d
Source IP Address Mask: e.f.g.h
Dest. IP Address: 0.0.0.0
Dest. IP Address Mask: 0.0.0.0
Protocol Type: 0