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Another technique of cicada filtering is McAdoo's filtering and water filtering in which you discard

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and allow packets based on the Mac address and reports.

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That is the incoming ports on which the data is getting received.

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Now, most of the time, it's wise to configure the access control list so that they'll allow or deny

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access based on the IP address of the source or destination device.

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Generally, we allow or deny IP packets based on the IP address from where they have received.

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Now, if a network is running on protocol other than the transmission control protocol or the Internet

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protocol, that is TCP IP, we can filter the traffic based on media access control.

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That is the MAC address or the hardware address.

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We have seen the hardware address in our networking sections.

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If we haven't seen the MAC or IP address or if we are confused about the Mac, please refer to the computer

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networking codes in which I have discussed everything about these addresses.

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Now we can still use a Mac address based access control list if we are running on the TCP IP.

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But I would like to tell you that it's a lot easier to deal with the IP address than the Mac address.

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Another point, remember, is that even though most firewalls and routers will allow you to create both

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IP based and Mac based access control list, doing so can create an exceptionally ugly situation where

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access is denied, then it really shouldn't be.

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So when it comes to Mac filtering or IP filtering, just make sure that you stick to only one of these

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because it is a lot easier to deal with IP address filtering.

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Now the next thing is both filtering access controls can also be used to filter based on the port numbers

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as well as the IP address.

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In fact, the most firewalls by default allow only open ports that we specify.

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This is another version of the implicit deny that is anything not allowed specifically is denied when

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managing a firewall.

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It is important to know the port numbers of all the traffic that needs to be allowed through it.

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If you do not know the port numbers on which you want to allow the traffic, there is no use of having

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a port filtering technique, right?

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You can't just randomly allow and disallow the port numbers.

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Now this means that for some of your applications you will need to read and learn the port numbers being

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used.

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This also explains why it's a big deal to know the port numbers of security protocols like SSL and IP

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sic.

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Successful management of firewall involves being aware of it and allowing only the ports to keep things

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running.

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For example, if you want to place a firewall on your network and if you do not know which ports does

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the traffic is actually sending and if you randomly on or off make of the port, there is no point in

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port filtering.

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OK, so make sure before you apply port filtering in your networks, you first must be acquainted with

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all the port numbers on which the protocols are using.

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That does it for this lecture.

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We have studied about the impact, filtering and filtering, which are another two techniques of security

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filtering.