Networking concepts – part 2 – OSI model & TCP/IP Model

Networking concepts – part 2 – OSI model & TCP/IP Model

OSI MODEL

osi_model

TCP/IP Model

osi_vs_tcp_iposi_tcp_models

How protocol stacks communicate

how_protocal_stacks_communicate

The basic principle of stack-based communication is that: Data from one layer of the stack can only be understood by the corresponding layer from the remote computer

This layer independence does have security implications: for example, giving a wrong IP address for a specific DNS service, id IP and DNS layers work together they would probably notice the fake IP, but because they work independently from each other they will not notice that. You need security software to check all the layers and make sure the headers are showing the correct info.

How TCP packets are created

how_tcp_packets_are_createdencapsulation_decapcultations

IP V4 header

IP-Header

IP V6 header

ip_v6_header

IP fragment attacks

  • Tiny fragment attack
  • Fragment overlap attack
  • Sending thousands of initial fragments without sending the rest of the packets could cause IP stack to crash.

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