Firewall - Lancom 1722 VoIP User Manual

All participants have fixed or dial-up connections to the Internet. Expensive
dedicated lines are no longer needed.
³
All that is required is the Internet connection of the LAN in the headquar-
ters. Special switching devices or routers for dedicated lines to individual
participants are superfluous.
·
The subsidiary also has its own connection to the Internet.
»
The RAS PCs connect to the headquarters LAN via the Internet.
The Internet is available virtually everywhere and typically has low access
costs. Significant savings can thus be achieved in relation to switched or ded-
icated connections, especially over long distances.
The physical connection no longer exists directly between two participants;
instead, the participants rely on their connection to the Internet. The access
technology used is not relevant in this case: ideally is the use of broadband
technologies such as DSL (Digital Subscriber Line). But also a conventional
ISDN line can be used.
The technologies of the individual participants do not have to be compatible
to one another, as would be the case for conventional direct connections. A
single Internet access can be used to establish multiple simultaneous logical
connections to a variety of remote stations.
The resulting savings and high flexibility makes the Internet (or any other IP
network) an outstanding backbone for a corporate network.
1.3

Firewall

The integrated Stateful Inspection Firewall ensures an effective protection
against undesired intrusion in your network by permitting only incoming data
traffic as reaction to outgoing data traffic. The router's IP masquerading func-
tion hides all workstations of the LAN behind a single public IP address. The
actual identities (IP addresses) of the individual workstations remain con-
cealed. Firewall filters of the router permit specific IP addresses, protocols and
ports to be blocked. With MAC address filters it is also possible to specifically
LANCOM 1722 VoIP – LANCOM 1724 VoIP
Chapter 1: Introduction
13