Part One – TCP Packet

In one digital city, where every device, every server, and every byte of data lives and interacts like characters in a big technological theater, there were two main characters: Paketik and Serverina.

The packet was a young and energetic message that was sent from one end of the city to the other to deliver important information. The server, on the other hand, was a wise and reliable server station that processed all the data that came to it.

One day, Packet had to deliver a very important message from its user, a young programmer, to Serverina. The message contained code that could significantly improve Serverina's performance.

The packet began its journey by establishing a connection. It knocked on Serverina's door, sending a special signal called SYN (synchronization). Serverina responded with a SYN-ACK signal, confirming that it was ready for dialogue and adding its own acknowledgement signal (ACK).

Then, the Packet happily sent his message, confident that Serverina was ready to receive it. As he transmitted the data, he waited for Serverina to confirm that she had received every piece of information. This was important, as the roads in the digital city could be crowded and data could get lost. But it wasn't enough. As soon as the Packet began sending data, the Evil One, who loved to wreak havoc on data transmissions, began interfering with the transmission, intercepting and hiding some of the Packet's messages.

The packet, noticing that its confirmations were not arriving on time, began using the timeouts that the Config wizard (sysctl) told it about, configured in accordance with the sysctl.conf parameters (net.ipv4.tcp_retries2 for
number of attempts to transmit data before reading the packet as lost and net.ipv4.tcp_syn_retries for the number of repeated SYN packets). Each time the timeout expired without receiving an acknowledgement from the Server, Packet would resend the data, making sure that every bit of information would be delivered.

Luckily, there was a security mechanism active on the network called Firewall Felix, which noticed the strange activity of the Evil One. Felix quickly intervened, using its algorithms to detect and block the Evil One, preventing it from interfering with data transmissions any further.

With Felix's help and clever use of timeouts, Packet successfully delivered all parts of the message. When all the information was transferred, he sent a FIN signal to inform Serverine that the transfer was complete, and Serverine acknowledged this with a FIN-ACK signal.

Thus, thanks to the reliable operation of the TCP protocol, the timeout mechanism and Felix's protection, the data was delivered safely and completely, and the Evil One was neutralized.

Data City has once again become a place for secure and efficient information exchange.

P.S. Read it as a fairy tale for children or beginners 🙂