14-32 User’s Reference Guide

and a packet goes through these rules destined for FTP, the packet would pass through the first filter rule (WWW), match the second rule (FTP) and the packet is allowed through. Even though the next rule is to deny all FTP traffic, the FTP packet will never make it to this rule.

Binary Representation

It is easiest when doing filtering to convert the IP address and mask in question to binary. This will allow you to perform the logical AND to determine if a packet matches a filter rule.

Logical ANDing

When a packet is compared (in most cases) a logical AND is performed. First the IP addresses and subnet masks are converted to binary and then ANDed together. The rules for logical ANDing are as follows:

0 AND 0 = 0

 

 

0 AND 1 = 0

 

 

1 AND 0 = 0

 

 

1 AND 1 = 1

 

 

For example:

 

 

Filter rule:

 

 

Deny

 

 

IP: 163.176.1.15

BINARY:

10100011.10110000.00000001.00001111

Mask: 255.255.255.255

BINARY: 11111111.11111111.11111111.11111111

Incoming Packet:

 

 

IP 163.176.1.15

BINARY:

10100011.10110000.00000001.00001111

AND the incoming packet and subnet mask together, the result is:

10100011.10110000.00000001.00001111

which matches the IP address in the filter rule and the packet is denied.

Implied Rules

With a given set of filter rules, there is an Implied rule which may or may not be shown to the user. The implied rule tells the filter set what to do with a packet that does not match any of the filter rules. An example of implied rules is as follows:

Implied

Meaning

 

 

Y+Y+Y=N

If all filter rules are YES, the implied is NO.

 

 

N+N+N=Y

If all filter rules are NO, the implied is YES.

 

 

Y+N+Y=N

If a mix of YES and NO filters, the implied is NO.

 

 

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Netopia R2121 manual Binary Representation, Logical ANDing, Implied Rules
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R2121 specifications

The Netopia R2121 is a powerful and versatile router designed for both home and office environments, providing seamless connectivity and robust performance for various networking needs. This device offers a range of features and technologies that cater to the demands of modern users seeking reliable internet access, speed, and security.

One of the standout characteristics of the Netopia R2121 is its dual-band technology, which operates on both the 2.4 GHz and 5 GHz frequency bands. This capability allows users to enjoy faster speeds and less interference, as the 5 GHz band is typically less congested than the traditional 2.4 GHz band. With the ability to support multiple devices simultaneously, the R2121 ensures that users can stream videos, play online games, and conduct video conferences without experiencing lag or connectivity issues.

The router is equipped with advanced security features, including WPA3 encryption, which provides enhanced protection against unauthorized access and data breaches. The R2121 also supports a robust firewall system that guards against external threats, ensuring that the user's network remains secure. Additionally, the router includes parental controls, allowing users to manage and restrict internet access for specific devices or set time limits for usage, making it an excellent choice for families.

Another significant advantage of the Netopia R2121 is its extensive coverage area. With high-gain antennas and advanced beamforming technology, the router can deliver strong and stable Wi-Fi signals even in larger homes or office spaces. This technology focuses the Wi-Fi signal directly toward connected devices, minimizing dead zones and improving overall connectivity.

The R2121 also supports both IPv4 and IPv6, ensuring compatibility with current and future internet technologies. This forward-thinking design makes it a future-proof solution for users looking to invest in a reliable router.

In terms of setup and management, the Netopia R2121 features a user-friendly web interface that allows users to easily customize settings, monitor network performance, and manage connected devices. The inclusion of mobile app support further enhances the user experience, enabling remote monitoring and control of the network from anywhere.

Overall, the Netopia R2121 stands out as a robust and reliable router that combines advanced features, enhanced security, and excellent performance, making it an ideal choice for home and business users alike. With its focus on delivering seamless connectivity and comprehensive management options, the R2121 is well-suited for today's connected lifestyles.
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