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Subnetting Mastery

Lately I’ve been working on a Subnetting Mastery video series. The goal is take someone with little to no exposure to subnetting and make them a subnetting pro. I’m happy to announce that the video series is finally complete! If anyone is working through or trying to learn subnetting, this is the video series for […]

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Cisco ASA NAT – Configuration Guide

This article provides all the information you need to understand and configure NAT on Cisco ASA and Cisco ASA-X Firewalls. There are  four possible methods of address translation, and each were defined in the Network Address Translation article series: Static NAT, Static PAT, Dynamic PAT, Dynamic NAT. This article assumes prior knowledge of each of […]

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Cisco NAT Configuration – IOS Router

In this article, we will illustrate the Cisco NAT configuration on IOS Routers. This is a follow up article to the Network Address Translation article series which thoroughly covered the operation of NAT and answers the questions “What is NAT?” and “How does NAT work?“. There are only four types of network address translation: Static NAT, Static PAT, […]

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VPN with Overlapping Networks

When connecting two sites together using a Virtual Private Network (VPN), a common issue that is encountered is trying to build a VPN with overlapping networks — where both sites happen to use the same Private IP addresses. In such cases, hosts on one side of the VPN tunnel will be unable to communicate with […]

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Cisco NAT Terminology

Cisco has created some NAT terminology which explicitly refer to the IP addresses and/or ports involved in Network Address Translation (NAT). While discussing the addresses involved in a NAT, using the terms like “Source” and “Destination” are common. However, using such terms can create some ambiguity. Specifically, the terms “Source” and “Destination” can create confusion […]

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Network Address Translation (NAT)

Every device on the Internet has an IP address. The IP address serves as the device’s identification – much like how a phone number identifies a particular phone. When devices communicate on the Internet, they are sending data from their IP address to the IP address of their intended destination. Sometimes, while data is en […]

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NAT Terminology Disambiguation

If you’ve made it here, then at this point you should have a solid understanding of each of the four types of translation that can exist: Static NAT, Static PAT, Dynamic PAT, and Dynamic NAT. Moreover, you have an understanding of Policy NAT and Twice NAT, which are simply two different ways of implementing the […]

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Policy NAT and Twice NAT

Every type of NAT we have discussed so far have two things in common. The first is that only the source of the packet is used to make a NAT decision. The second is that only the source of the outbound packet is translated. Policy NAT and Twice NAT are two ways of performing any […]