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So we have learned that a source snapped for outgoing connection and a destination at for income in

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connection.

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No let's make things a bit more complex.

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We also need to understand what is a dynamic net and what is a static net well a dynamic net maps the

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private IP addresses to the first available public address from a pool of possible addresses that you

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have got from your ISP in 48.

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This can be done using IP pools.

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The second type of a dynamic net is net overloading.

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This is the net that we use in our home.

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That kind of and net maps multiple private IP addresses to a single only one public IP address.

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How does it differentiate between the different client.

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It does so by using a different source port assignment.

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Now assume that this source port for a specific client is port number one thousand seventy two for another

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client the port this source port is one hundred and seventy three.

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Whenever a session is initiated it is initiated with the source port.

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Whenever the web server lets assume that we have asked for a web page whenever a web server since the

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responding traffic it is based on those port numbers so each session is actually mapped with this source

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port that the client initiated.

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Now let's take a look at our firewall policy and let's understand how we configure and net overloading

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and how we configure IP pools.

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All right so let's move over to one of our policies and see the different net that is being used.

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Now as you can see it can you.

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You can enable that or disable it if you choose the use of the use of outgoing interface address that

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is many to one many private addresses will use only one public IP address.

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That is the net overload but you can also use net overload in dynamic IP pools.

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Now we don't have any IP pool that is configure so we can add one right now.

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So if we use IP pools we actually use a range of IP addresses instead of the egress interface as we

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saw before we can name or pull its name it IP poll.

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And as we can see we have four types of IP pools.

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The first one is overload.

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There is many to want.

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There are many to a few IP addresses and the port translation is used.

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The second one one two one.

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Well the IP address the private IP address is being mapped on a first come first served.

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And we don't use the port address translation.

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Now the third one the fixed or 3G range allows better mapping between the internal private address and

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the external IP address.

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It also doesn't use Port address translation No.

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The third one the port block on location.

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It allows you to limit your client to a number of ports that can be used.

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You can use a specific number of port blocks size.

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Let's say that we use 65 clients with limited port block size.

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We're less likely to be influenced by a distributed denial of service where your network suffers from

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a flow of ICMP messages.