Firewall - Lancom 1723 VOIP User Manual

LANCOM 1722 VoIP – LANCOM 1723 VoIP – LANCOM 1724 VoIP – LANCOM 1823 VoIP
Chapter 1: Introduction
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: Broadband technology such as
DSL (Digital Subscriber Line) is ideal. A conventional ISDN line can be used,
too.
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 sites.
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 is an effective barrier to unwanted
data traffic as it only permits the entry of data as a response to outgoing data
traffic. The IP masquerading function in the router conceals LAN workstations
accessing the Internet behind a single public IP address. The true identities (IP
addresses) of the individual workstations remain masked. Router firewall fil-
ters allow the blocking of individual IP addresses, protocols and ports. MAC
address filters also offer effective control over the access of LAN workstations
to the IP routing functions in the device.
Further important features in the firewall are:
14
INTERNET
FIREWALL
Intrusion detection
Router
PC
PC
Server