Classful Addressing/FLSM/VLSM/CIDR

Classful Addressing

This addressing strategy is the oldest one used back in the days. Nowadays, we don’t work with it but lecturers are still teaching it to help students understand and analyse the addressing strategies.

Main idea of classful addressing is dividing IPs by certain subnet masks and create classes from them. There are five classes extracted by classful addressing and each of them has their own usages and attributes.


This is an old addressing and there was a lot of wastage of IPs.The idea was, if you were a company that needed 200 IP addresses, a class C assignment would have been provided. If you were a company that needed 50,000 IP addresses, a class B would have been provided. And if you were one of the few companies that justified requiring over 65k~ IP addresses, you would be given a Class A.

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HTTPS and TLS (SSL 3+)

TLS is Next Generation SSL

When people talk about SSL(Secure Socket Layers) protocol, what they actually mean is TLS(Transport Layer Security). TLS is the successor and the new name of SSL.

SSL 3.1 is actually TLS 1.0. TLS 1.1 is SSL 3.2 and TLS 1.2 is SSL 3.3. TLS 1.3 is the latest version proposed on 21 March 2018.

Now that you know these, let’s get into TLS.

What is TLS?

TLS is a protocol operating directly on top of TCP layer. Although, there are implementations of it for Datagram Based Protocols like UDP. By working on TCP layer, protocols on higher level layers(Application layer …) are left unchanged while still being secure. Below TLS layer, HTTP is identical to HTTPS.

OSI Model

When you use TLS properly on your connections, attackers can only see which IP and port you are connecting, roughly how much data you are sending and what kind of encryption algorithm and compression are being used.
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