Specifications

Security 2009
KNOW-HOW: Remote Access
S20
KNOW-HOW · KNOW-HOW · KNOW-HOW · KNOW-HOW · KNOW-HOW · KNOW-HOW · KNOW-HOW
Step 2: Portforwarding
Now we know how a connection is made to the router which then only
has to be told what to do with such a request. The IP addresses of the
units connected to the router cannot be viewed directly from the Internet.
Thus, the router has to forward these requests to the respective units (to
route).
Unfortunately, this forwarding feature is called differently by every
manufacturer for routers. Sometimes, it is called portforwarding, some-
times NAT, or virtual server.
Description of the individual points
A : Name for e.g. the DVR, selectable as desired
B : Protocol (TCP in most cases), refer to instr. manual of the DVR
C : Port which is to be accessed externally.
D : Internal, actual IP of the DVR
E : Actual set port number of the DVR
What happens now if the DVR is accessed?
When the previously selected address http://video-test.dyndns.org:80 is
entered into the Internet browser, it is forwarded to port 80 of the
router via dyndns.org. Port 80 is the standard port for access via web
browser. It does not have to be entered separately again when enter-
ing the address.
When configuring the router, we have set up that requests are for-
wared to the internal address 192.168.1.125 and the port 80 here
via the official port 80.
If the address is amended as follows:
http://video-test.dyndns.org:82, the forwarding is changed. By
entering another port,
port 82 in this case, the router will then forward
the request to the internal address 192.168.1.63 Port 80.
With this forwarding, it is now possible to access the digital recorder
via the Internet.
Depending on the type of digital recorder, it may be necessary to set
up further portforwardings. The data on the port numbers used can
be found in the respective instruction manuals.
It may be necessary to carry out further adjustments to the Firewall
which may exist, depending on the set up and security level of the net-
work. For information on this subject and to IP addresses and port
numbers which can be used, please contact the respective network ad-
ministrator.
This example shows the respective menu of the applied router Draytek Vigor 2500WE .