So we have learned that a source snapped for outgoing connection and a destination at for income in
connection.
No let's make things a bit more complex.
We also need to understand what is a dynamic net and what is a static net well a dynamic net maps the
private IP addresses to the first available public address from a pool of possible addresses that you
have got from your ISP in 48.
This can be done using IP pools.
The second type of a dynamic net is net overloading.
This is the net that we use in our home.
That kind of and net maps multiple private IP addresses to a single only one public IP address.
How does it differentiate between the different client.
It does so by using a different source port assignment.
Now assume that this source port for a specific client is port number one thousand seventy two for another
client the port this source port is one hundred and seventy three.
Whenever a session is initiated it is initiated with the source port.
Whenever the web server lets assume that we have asked for a web page whenever a web server since the
responding traffic it is based on those port numbers so each session is actually mapped with this source
port that the client initiated.
Now let's take a look at our firewall policy and let's understand how we configure and net overloading
and how we configure IP pools.
All right so let's move over to one of our policies and see the different net that is being used.
Now as you can see it can you.
You can enable that or disable it if you choose the use of the use of outgoing interface address that
is many to one many private addresses will use only one public IP address.
That is the net overload but you can also use net overload in dynamic IP pools.
Now we don't have any IP pool that is configure so we can add one right now.
So if we use IP pools we actually use a range of IP addresses instead of the egress interface as we
saw before we can name or pull its name it IP poll.
And as we can see we have four types of IP pools.
The first one is overload.
There is many to want.
There are many to a few IP addresses and the port translation is used.
The second one one two one.
Well the IP address the private IP address is being mapped on a first come first served.
And we don't use the port address translation.
Now the third one the fixed or 3G range allows better mapping between the internal private address and
the external IP address.
It also doesn't use Port address translation No.
The third one the port block on location.
It allows you to limit your client to a number of ports that can be used.
You can use a specific number of port blocks size.
Let's say that we use 65 clients with limited port block size.
We're less likely to be influenced by a distributed denial of service where your network suffers from
a flow of ICMP messages.