Unified Security Gateway User's Guide

Chapter 10 Interface
ZyWALL USG 300 User’s Guide
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PPPoE is often used with cable modems and DSL connections. It provides the following
advantages:
• The access and authentication method works with existing systems, including RADIUS.
• You can access one of several network services. This makes it easier for the service
provider to offer the service
• PPPoE does not usually require any special configuration of the modem.
PPTP is used to set up virtual private networks (VPN) in unsecure TCP/IP environments. It
sets up two sessions.
1 The first one runs on TCP port 1723. It is used to start and manage the second one.
2 The second one uses Generic Routing Encapsulation (GRE, RFC 2890) to transfer
information between the computers.
PPTP is convenient and easy-to-use, but you have to make sure that firewalls support both
PPTP sessions.
10.6.2 PPPoE/PPTP Interfaces Overview
In the ZyWALL, you may use PPPoE/PPTP interfaces to connect to your ISP. This way, you
do not have to install or manage PPPoE/PPTP software on each computer in the network.
Figure 138 Example: PPPoE/PPTP Interfaces
PPPoE/PPTP interfaces are similar to other interfaces in some ways. They have an IP address,
subnet mask, and gateway used to make routing decisions; they restrict bandwidth and packet
size; and they can verify the gateway is available. There are two main differences between
PPPoE/PPTP interfaces and other interfaces.
1 You must set up an ISP account before you create a PPPoE/PPTP interface.
Each ISP account specifies the protocol (PPPoE or PPTP), as well as your ISP account
information. If you change ISPs later, you only have to create a new ISP account, not a
new PPPoE/PPTP interface. You should not have to change any network policies.
2 You do not set up the subnet mask or gateway.
PPPoE/PPTP interfaces are interfaces between the ZyWALL and only one computer.
Therefore, the subnet mask is always 255.255.255.255. In addition, the ZyWALL
always treats the ISP as a gateway.
At the time of writing, it is possible to set up the IP address of the gateway (ISP) using CLI
commands but not in the web configurator.