Another technique of cicada filtering is McAdoo's filtering and water filtering in which you discard
and allow packets based on the Mac address and reports.
That is the incoming ports on which the data is getting received.
Now, most of the time, it's wise to configure the access control list so that they'll allow or deny
access based on the IP address of the source or destination device.
Generally, we allow or deny IP packets based on the IP address from where they have received.
Now, if a network is running on protocol other than the transmission control protocol or the Internet
protocol, that is TCP IP, we can filter the traffic based on media access control.
That is the MAC address or the hardware address.
We have seen the hardware address in our networking sections.
If we haven't seen the MAC or IP address or if we are confused about the Mac, please refer to the computer
networking codes in which I have discussed everything about these addresses.
Now we can still use a Mac address based access control list if we are running on the TCP IP.
But I would like to tell you that it's a lot easier to deal with the IP address than the Mac address.
Another point, remember, is that even though most firewalls and routers will allow you to create both
IP based and Mac based access control list, doing so can create an exceptionally ugly situation where
access is denied, then it really shouldn't be.
So when it comes to Mac filtering or IP filtering, just make sure that you stick to only one of these
because it is a lot easier to deal with IP address filtering.
Now the next thing is both filtering access controls can also be used to filter based on the port numbers
as well as the IP address.
In fact, the most firewalls by default allow only open ports that we specify.
This is another version of the implicit deny that is anything not allowed specifically is denied when
managing a firewall.
It is important to know the port numbers of all the traffic that needs to be allowed through it.
If you do not know the port numbers on which you want to allow the traffic, there is no use of having
a port filtering technique, right?
You can't just randomly allow and disallow the port numbers.
Now this means that for some of your applications you will need to read and learn the port numbers being
used.
This also explains why it's a big deal to know the port numbers of security protocols like SSL and IP
sic.
Successful management of firewall involves being aware of it and allowing only the ports to keep things
running.
For example, if you want to place a firewall on your network and if you do not know which ports does
the traffic is actually sending and if you randomly on or off make of the port, there is no point in
port filtering.
OK, so make sure before you apply port filtering in your networks, you first must be acquainted with
all the port numbers on which the protocols are using.
That does it for this lecture.
We have studied about the impact, filtering and filtering, which are another two techniques of security
filtering.