Outbound Dmz Traffic Options - D-Link NetDefend SOHO DFL-160 User Manual

4.2. Outbound DMZ Traffic Options

4.2. Outbound DMZ Traffic Options
The Meaning of Outbound
These options determine what types of traffic can pass between the DMZ network and the WAN
interface when the connection is initiated by a client or host on the DMZ network.
For instance, the retrieval of data from a web server on the public Internet is still considered part of
outbound traffic if the retrieval request is initiated by a web surfer sitting on the DMZ network.
The options on the page of the web interface follow the same pattern described for the LAN
interface described in Section 4.1, "Outbound LAN Traffic Options" although there are some
differences.
Allowing Services
A Service refers to a higher level protocol such as the HTTP protocol used for web surfing and is a
convenient way of identifying different types of data traffic. The presentation of the first few
choices in the web interface is shown below.
By default, all services are allowed, that is to say, no connections initiated from the DMZ network
are blocked.
It is recommended, however, to try and impose restrictions that match the expected needs of the
clients and hosts on the DMZ network.
Connections from the DMZ to the LAN
Connections initiated from the DMZ network to hosts on the LAN network are never allowed.
However, the opposite is always true: connections initiated by hosts on the LAN network are always
allowed to the DMZ network.
This arrangement prevents a host that becomes infected on the DMZ spreading the problem to the
LAN network. This implements one of the prime purposes of the DMZ which is to be a network
where hosts which receive connections from the public Internet can be placed.
Specifying Custom Traffic
By clicking the Custom Traffic tab and then selecting Add > Custom Traffic, it is possible to
allow through a protocol not specified in the pre-defined list.
For a custom protocol it is necessary to specify if the protocol uses TCP or UDP connections or
both and to specify the port number that the protocol will try and connect to at the other end of the
connection. The presentation of the new custom rule options in the web interface is shown below.
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Chapter 4. The Firewall Menu