preface

Although most of the exam questions are some basic vocabulary questions, but obviously can be seen, if you do not have a deep foundation, is not good. I called the network security engineer.

1. Describe three TCP entries and write the SYN ACK relation

I answer: First handshake: When a connection is established, the client sends a SYN packet (SYN = J) to the server and enters the SYN_send state, waiting for confirmation from the server. Second handshake: The server receives a SYN packet from the client. The server must acknowledge the client’s SYN (ACK =j+1) and send a SYN packet (SYN =k). The server enters the syn_recv state: The client receives a SYN + ACK packet from the server and sends an ACK packet (ACK = K +1) to the server. Then the data wave is sent. The client and server enter the Established state to complete the three-way handshake. SYN is the send flag bit, and ACK is the acknowledge flag bit

2: describes the differences between TCP and UDP. Describe the p2p mechanism and its development prospects

My answer:

Differences: TCP – Transmission control protocol, which provides a connection-oriented, reliable byte stream service. Before the client and server exchange data, a TCP connection must be established between them before data can be transmitted. TCP provides functions such as resending timeout, discarding duplicate data, verifying data, and controlling traffic to ensure that data can be transmitted from one end to the other.

UDP – user datagram protocol, is a simple datagram – oriented transport layer protocol. UDP does not provide reliability; it simply sends datagrams from applications to the IP layer, but there is no guarantee that they will reach their destination. UDP does not need to establish a connection between the client and the server before transmitting data packets, and there is no timeout retransmission mechanism, so the transmission speed is very fast

Pros and cons: When data transmission performance must give way to data transmission integrity, control, and reliability, TCP is the preferred protocol. UDP is the best choice when emphasizing transmission performance over transmission integrity, such as audio and multimedia applications. UDP is also a good choice in cases where the data transfer time is so short that the previous connection process becomes the bulk of the traffic, such as DNS switching.

P2p mechanism description: P2P is short for peer-to-peer, also known as “peer-to-peer”. “Peer-to-peer” technology is a new type of networking that relies on the computing power and bandwidth of participants in a network, rather than pooling dependencies on a small number of servers. P2P is also short for Point to Point. It is a download term, meaning that you download at the same time, their own computer will continue to host, this kind of download, the more people the speed is faster but the disadvantage is relatively large damage to the hard disk (in writing at the same time but also read), there are more memory occupation, affecting the speed of the machine.

Development prospects: P2P technology is good at maximizing the use of idle network resources, this application in high-energy physics, nuclear physics, meteorology, hydrology, space research and other massive computing fields have huge application prospects. Because P2P technology is based on IPV6 protocol, and IPV6 address allocation is an astonishing astronomical number, in the near future, with P2P technology support, you can use your mobile phone to control the switch of your own light. Products often need to be patched to address bugs or security concerns found after they are launched. P2P technology makes it easy to distribute products. All people who own such products automatically form a Workgroup and have strict identity authentication. The product manufacturer provides the upgrade patch service here at any time, and the P2P technology will enable your computer to complete the patch and various upgrade services unconsciously. Those who have a little knowledge of wireless business should know that our MMS still need the forwarding of carrier Server to achieve. Have you ever thought that when you encounter an exciting scene, you just need to point the camera of your mobile phone at it, and you can directly send the scene to your friends in the form of Video. These scenes seem to be only in science fiction movies, but in P2P technology, it is completely convenient to achieve.

Thanks to everyone who read my article carefully, here are some more materials to give away, though not very valuable things, you can take them from the home page if you need them:

① More than 2000 network security e-books (mainstream and classic books should be available)

② Network security Standard Question Bank information (the most complete Chinese version)

③ project source code (forty or fifty interesting and classic practice projects and source code)

④ Network security basic introduction, Linux, Web security, attack and defense video (suitable for small white learning)

⑤ Network security learning roadmap (bid farewell to unpopular learning)