Seungyoon (Dan) Lee's Blog

Class 8, The Bitcoin Blockchain

Up until now during our class periods, we have focused our cue in learning about the client-server network architecture. Client-server is often referred as the "classic" network architecture. Yet, there are relatively newborn and/or different network architectures, such as the peer-to-peer (P2P) and distributed computing architectures. In this blog post, I would like to elaborate and explain further details regarding the topic of the Bitcoin Blockchain, especially focusing on the "blockchain" aspects of the recently developed "Bitcoin."

Bitcoin, in a non-tech-savvy wording, simply is a form of digital currency that enables users' financial transactions without the physical need for a credit card or a bank. Simply put, it can be rendered as a digital currency backed up by the conceptual bank of the internet, or the "online bank." Bitcoin is geared to allow its users to send and receive money over the web in the simplest way. The Bitcoin system and features are initially backed up by the peer-to-peer network. The bitcoin's transaction management is done by the blockchain of bitcoin, which I will explain further, and the initial issuance of bitcoins is collectively executed by the network that serves as the base.

The "blockchain" aspect of the bitcoin is one of the critical facets that allow bitcoin to operate. The "blockchain" works as a public ledger (book) of all the transactions in the Bitcoin network. The website, (Blockchain.info) enables users to navigate the bitcoin blockchain. This concept of the blockchain can be summarized as the official documentations for the online financial transactions made through the use of bitcoins. This transaction database, which is shared by all the users participating in the bitcoin transactions, guarantee the clarity of the transactions.

Class 8, Peer-to-Peer (P2P) & Bit-Torrent

Up until now during our class periods, we have focused our cue in learning about the client-server network architecture. Client-server is often referred as the "classic" network architecture. Yet, there are relatively newborn and/or different network architectures, such as the peer-to-peer (P2P) and distributed computing architectures. In this blog post, I would like to elaborate and explain further details regarding the topic of peer-to-peer networks and the Bit-Torrent network structure.

Simply explained, a P2P network can be created when two or more personal computers are connected, with resources sharing capability without using, or going through, a separate server computer. This form of network can be considered as an "ad hoc" connection. An ad hoc connection can be referred to couple computers connected through universal serial bus to transfer data. A P2P network can be a viable network on a bigger picture, when special applications are established to allow direct relationships among numerous internet users. The P2P network was first established in the early 80s, and nowadays, it is a common internet network structure that millions of users utilize to send and receive files and data over the internet, with greater ease.

BitTorrent is a protocol for the actual practice of P2P networks. BitTorrent is one of the most common and general protocols used in transferring large sized files. BitTorrrent's popularity can be supported by the fact that it was responsible for more than 3% of the worldwide bandwidth, a shockingly big number considering 6% of worldwide bandwidth was used in filesharing. We have discovered that BitTorrent is a famous platform that realized the functions and objectives of the peer-to-peer networks.

Class 8, Botnets & Zombie Networks

A botnet is comprised of internet connected applications that communicate with synonymous and/or highly similar programs, for the purpose of performing tasks. The etymology of "Botnet" comes from a mere combination of the two words, robot and network. The botnets can be utilized to send spam mails or participate in DDOS (distributed denial of service) attacks. Due to such qualities, the word botnet often carries a negative, or detrimental nuance. The Norton Security considers Bots as "one of the most complicated and popular types of cybercrime today." Bots allow hackers to manipulate multiple computers, eventually allowing them to turn individual computers into a zombie computer. A zombie computer operates as a component of the bot networks to spread spams, viruses, and other detrimental factors into computers. Online crimes and frauds are facilitated through the usage of botnets and zombie computers.

The size of the botnet is critical. Some botnets can have more than thousands of zombie computers, while there are also small ones, comprised of merely ten computers. Many of these computers infection state is unbeknownst to the actual users. Bots are spread out in the internet in forms of different malwares. Bots hide themselves until they are pin-pointed to attack, or basically carry out a simple task. For protection against bots, individual computer and internet users should always configure the software settings to be up to date, limit user rights, reinforce internet user security settings, never click on dubious attachments in emails and obvious spams, and many more.

Class 8, The YouTube Network and ISPs

The Google Video Quality Report shows the biology/mechanics of how the numerous YouTube videos travel from the internet to our eyes. Below are the screenshots I took while I was learning more on the subject, with a short description of the image attached.

Youtube has multiple servers for many videos, thus the closest server provides us the video we try to stream

Just like a car navigation system, Youtube transports the video data to our ISP with the highest efficiency achievable

This part denotes that data capacity and flow conditions must meet the standard to successfully carry video data to our home, through the internet service providers

This part delineates the fact that the power and capacity of the different ISPs may affect varying speed results in bringing the videos to individual homes or offices

This part highlights the idea that if an internet connection is congested, the speed of streaming will slow down significantly

The test results for my ISP, denoting Standard Definition, which means: "users on networks rated as Standard Definition should expect smooth playback on standard definition Youtube videos (360p) and may experience occasional interruptions on HD Youtube videos (720p and above)."