Tunnel Technology - Fritz! Fon WLAN 7390 Installation, Configuration And Operation

Tunnel Technology

5.3 Tunnel Technology
The VPN tunnel fulfills these security requirements. The
VPN tunnel is implemented using a tunnel protocol.
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.
IP header
New
IP header
IP header
•
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.
Data
Data
encrypted
162
Original packet
Tunnel packet