TryHackMe | Packets & Frames

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• A frame is at layer 2 - the data link layer, meaning there is no such information as IP addresses.

• it's safe to assume that when we are talking about anything IP addresses, we are talking about packets. When the encapsulating information is stripped away, we're talking about the frame itself.

• Checksum This field provides integrity checking for protocols such as TCP/IP. If any data is changed, this value will be different from what was expected and therefore corrupt.

• One defining feature of TCP is that it is connection-based, which means that TCP must establish a connection between both a client and a device acting as a server before data is sent.

• This process is named the Three-way handshake,

• A packet using this protocol will have a set of headers

• 0-65535

• Sequence Number When a connection occurs, the first piece of data transmitted is given a random number. We'll explain this more in-depth further on.

• Acknowledgement Number After a piece of data has been given a sequence number, the number for the next piece of data will have the sequence number + 1. We'll also explain this more in-depth further on.

• This packet is used to cleanly (properly) close the connection after it has been complete.

• RST This packet abruptly ends all communication. This is the last resort and indicates there was some problem during the process. For example, if the service or application is not working correctly, or the system has faults such as low resources.

• Any sent data is given a random number sequence and is reconstructed using this number sequence and incrementing by 1.

• Because TCP reserves system resources on a device, it is best practice to close TCP connections as soon as possible.

• web browsers now share one common rule: data is sent over port 80.

• 443

• 445

• 3389

• Packets and frames are small pieces of data that, when forming together, make a larger piece of information or message.

• irst envelope will be the packet that you mail, but once it is opened, the envelope within still exists and contains data (this is a frame). This process is called encapsulation

• Packets are an efficient way of communicating data across networked devices