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151
Changing the Network Settings
2.
Select the “Network Settings” tab.
3.
Click the “IP Addresses” button.
The “IP Settings” page is opened.
4.
Once all desired changes to the settings have been
configured, confirm by clicking “OK” to apply them.
Please note that changes to the network settings in the
FRITZ!Box may make it necessary to adjust the network
settings of your computers so that you can continue to ac-
cess the FRITZ!Box user interface.
Page 152 / 190
More about Internet Telephony
152
4
More about Internet Telephony
Voice over IP (VoIP)
Internet telephony has already been in use for years, but
today it allows even private customers the convenience fa-
miliar from conventional telephony, usually at significant-
ly lower prices.
Internet telephony has also made it considerably more
convenient to use applications like conference calls and
answering machines in networks. Further advantages in-
clude global availability at a single telephone number,
and the development of new standards for security and
voice quality.
Data Transfer
All kinds of data transmission in the Internet use the Inter-
net Protocol (IP). IP is packet-oriented. This means that
the data are broken down into data packets for transmis-
sion and IP takes care of the transport of the individual
data packets through the Internet. Language is also trans-
mitted in the Internet in this manner.
In opposition to this, fixed-line telephony transmits data
in a line-oriented manner. In this case data are transmit-
ted in a coherent data stream.
4.1
Telephony Scenarios
If you have configured both a fixed-line number and an In-
ternet telephone number in FRITZ!Box, you can make calls
in all directions:
from the fixed-line network into the fixed-line net-
work
from the Internet into the fixed-line network
from the Internet into the Internet
and receive calls from all directions as well.
Page 153 / 190
153
More about Virtual Private Network (VPN)
5
More about Virtual Private Network (VPN)
Via VPN a secure remote access to the network of the FRITZ!Box can be
established.
The VPN solution for the FRITZ!Box is based on the IPSec standard.
Computer-LAN coupling and LAN-LAN coupling: VPN connections
can be set up for individual remote computers or even for remote
networks.
Eight simultaneous active VPN connections are supported.
The configuration files for the VPN connections are created using a
separate program. The program is provided free of charge and can
be downloaded from the AVM web site.
A free VPN client for individual computers can also be downloaded
from the AVM web site.
The chapter is a short introduction to the topic of VPN. The
AVM web site offers an English-language Service Portal
which presents comprehensive information on VPN in
general and in connection with the FRITZ!Box. Visit this
portal to obtain more detailed information on this subject.
www.avm.de/en/vpn
5.1
What Is VPN?
VPN stands for Virtual Private Network. A VPN is a virtual,
private network that uses the Internet as its physical base.
The VPN provides for secure data transmission.
All computers registered in the network are connected
with each other over the Internet so that they can ex-
change data. Data transmission takes place over IP, as in
the local network. In a pure transmission over IP the data
are not protected and thus exposed to unauthorized ac-
cess by third parties.
Security in a VPN is ensured by transmitting the data en-
crypted via what is known as tunnel. This excludes the
possibility of unauthorized access to the data. The tunnel
is the logical, virtual connection.
Page 154 / 190
Security through a VPN
154
The terminals of the tunnels can be individual computers
or entire networks. For instance, telecommuters or field
staff can connect to the company network via VPN. The lo-
cal network at a branch office can also be connected to
the local network of company headquarters via VPN. Both
of the locations securely connected over VPN must have
an Internet connection at their disposal.
5.2
Security through a VPN
A VPN fulfills the following security requirements for data
transmission:
authenticity
confidentiality
integrity
Authenticity
Authenticity ensures that no unauthorized users can ac-
cess the local network via VPN.
It also makes sure that incoming data actually come from
the registered party and not from another source.
Confidentiality
Confidentiality requires the nondisclosure of data. Confi-
dentiality can be guaranteed by encrypting the data.
Encryption means that unauthorized third parties cannot
obtain any knowledge about the transmitted data.
Integrity
Integrity ensures that the data are not changed, recorded
or diverted during transmission.
Tunnel
Tunnel
Local network A
Local network B
Internet
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155
The Tunnel Technology
The VPN tunnel fulfills these security requirements. The
VPN tunnel is implemented using a tunnel protocol.
5.3
The Tunnel Technology
A tunnel is created by placing an IP packet to be transmit-
ted inside of an additional, new IP packet.
An IP packet is composed of the IP header and the user
data. The IP header contains the IP address of the destina-
tion and the IP address of the sender.
The original packet is encrypted and authenticated before
repacking.
The IP addresses of the destination and the sender in
the new IP header are the public IP addresses of the
two VPN parties in the Internet. Only the new IP head-
er can be read in the Internet in clear text.
Thanks to the encryption and authentication, the
original packet remains concealed in the inside of
the tunnel. The IP addresses of the destination and
sender in the IP header of the original packet are pri-
vate IP addresses in the local network.
The tunnel is what makes it possible to connect networks
with private IP addresses via the Internet. Moreover, the
tunnel secures the connection.
The VPN solution used with the FRITZ!Box uses the IPSec
tunnel protocol.
IP header
Data
IP header
Data
New
IP header
Original packet
Tunnel packet
encrypted

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