Virtual Private Networks (VPNs) 12-23

■Select IP Profile Parameters and press Return. The IP Profile Parameters screen appears.

IP Profile Parameters

Address Translation Enabled:

Yes

NAT Map List...

Easy-PAT

NAT Server List...

Easy-Servers

Local WAN IP Address:

0.0.0.0

Remote IP Address:

173.167.8.10

Remote IP Mask:

255.255.0.0

Filter Set...

 

Remove Filter Set

 

Receive RIP:

Both

Enter a subnet mask in decimal and dot form (xxx.xxx.xxx.xxx).

■Enter the Remote IP Address and Remote IP Mask for the host to which you want to tunnel.

Allowing VPNs through a Firewall

An administrator interested in securing a network will usually combine the use of VPNs with the use of a firewall or some similar mechanism. This is because a VPN is not a complete security solution, but rather a component of overall security. Using a VPN will add security to transactions carried over a public network, but a VPN alone will not prevent a public network from infiltrating a private network. Therefore, you should combine use of a firewall with VPNs, where the firewall will secure the private network from infiltration from a public network, and the VPN will secure the transactions that must cross the public network.

A strict firewall may not be provisioned to allow VPN traffic to pass back and forth as needed. In order to ensure that a firewall will allow a VPN, certain attributes must be added to the firewall's provisioning. The provisions necessary vary slightly between ATMP and PPTP, but both protocols operate on the same basic premise: there are control and negotiation operations, and there is the tunnelled traffic that carries the payload of data between the VPN endpoints. The difference is that ATMP uses UDP to handle control and negotiation, while PPTP uses TCP. Then both ATMP and PPTP use GRE to carry the payload.

For PPTP negotiation to work, TCP packets inbound and outbound destined for port 1723 must be allowed. Likewise, for ATMP negotiation to work, UDP packets inbound and outbound destined for port 5150 must be allowed. Source ports are dynamic, so, if possible, make this flexible, too. Additionally, PPTP and ATMP both require a firewall to allow GRE bi-directionally.

The following sections illustrate a sample filtering setup to allow either PPTP or ATMP traffic to cross a firewall:

■PPTP example on page 12-24

■ATMP example on page 12-27

Make your own appropriate substitutions. For more information on filters and firewalls, see Chapter 13, “Security.”.

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Netopia 4752 manual Allowing VPNs through a Firewall, Pptp example on Atmp example on
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4752 specifications

The Netopia 4752 is a versatile networking device that serves as a digital subscriber line (DSL) modem and router, designed to provide high-speed internet connectivity and advanced networking capabilities for home and small office environments. This device is notable for its reliability and ease of use, making it a popular choice among users looking for seamless internet access.

One of the main features of the Netopia 4752 is its support for various DSL technologies, including ADSL and ADSL2+. This compatibility ensures that users can achieve optimal bandwidth and speed, even on legacy DSL lines. The modem’s capability to handle downstream speeds of up to 24 Mbps allows for smooth streaming, gaming, and browsing experiences.

Equipped with a robust built-in router, the Netopia 4752 offers multiple Ethernet ports for direct wired connections, accommodating multiple devices simultaneously. This feature is especially beneficial in environments where multiple users need to access the internet without latency. Additionally, the device supports wireless connectivity, enabling users to connect their laptops, smartphones, and other Wi-Fi-enabled devices effortlessly.

Security is a crucial aspect of the Netopia 4752’s functionality. The device incorporates a built-in firewall and supports various security protocols, including WPA and WPA2, ensuring that users’ data remains protected from unauthorized access. The user-friendly web-based interface facilitates easy configuration of security settings, making it accessible even for those with limited technical knowledge.

The Netopia 4752 also features advanced Quality of Service (QoS) settings that allow users to prioritize bandwidth for specific applications or devices. This capability is crucial for households or offices that demand high performance for video conferencing, streaming services, or online gaming.

In terms of characteristics, the Netopia 4752 boasts a compact form factor, making it easy to integrate into any workspace without occupying much space. Its durable design ensures longevity, providing reliable service over time.

Overall, the Netopia 4752 stands out as a dependable DSL modem and router solution, with its high-speed internet capabilities, security features, and flexible connectivity options suitable for both home and small office users who require efficient and effective internet access.
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