CSDN blockchain training
The deposit fee of 100 yuan for registration can be returned after completing all courses
tutoring class was given under the line, and the lecture lasted for 4 days, with 7800 yuan per person
RMB 88888 per person for 3 days and 2 nights
What is...
blockchain? Maybe few people can really answer this question. It is precisely because of the inherent mystery of "blockchain", that many people are eager to pay for knowledge in order to get on the train to the "future"
therefore, all kinds of blockchain training are also very popular, and all kinds of information, such as "scanning code, entering the group to listen to lectures", are filled with the circle of friends, so it is difficult to distinguish the good from the bad. The training costs are even more uneven: 100 yuan, 300 yuan, 7000 yuan or even nearly 100000 yuan...
blockchain training is too hot
I often make up my identity on the dating materials, such as import lighting wholesalers, urban landscape designers, boutique tobacco hotel owners and agricultural loan salesmen. Now, I have finally become an expert in blockchain training courses
} photo source: a screenshot of a recruitment website
and it is reported that a blockchain recruitment advertisement in Beijing recently blew up the circle of friends, requiring candidates to have in-depth research on blockchain technology and cryptography, giving an annual salary of not less than 5 million yuan, and not capped
"this is really the current situation of blockchain talent recruitment. But even so, we can't find people, because it's hard to find qualified people. " Lu Sheng, head hunter of Liepin platform, said
Song Mofei, senior researcher of Suning Institute of finance, said: "in terms of development experience, the rise of domestic blockchain instry has been concentrated in the last two or three years, and few people have long-term blockchain development experience in the talent market." He believes that excessive salary will inevitably attract some speculators, but the increase of salary does not bring about the increase of the application threshold, and even some recruiters only know a little about blockchain technology, which also poses new challenges for the recruitment of blockchain talents
according to Shan Yi, chief data officer of liepin.com, the core of blockchain is the change of social relations and business model based on Internet distributed trust system, which is characterized by decentralization“ There are still many uncertainties in the future development of block chain. There are obvious bubbles at present, and many block chain projects are not reliable. He said
Yin Cheng, a graate of Tsinghua University, is a top professional in the field of blockchain in China. He is proficient in C / C + +,, golang, python, kalilinux, sicikit learn and tensorflow. He is an EOS open source contributor and has developed many blockchain cryptocurrencies. He once served as Google algorithm engineer and a gold medal lecturer in Microsoft tech.ed conference. He is the most valuable expert in the field of artificial intelligence and blockchain in the world. He also has 15 years of programming experience and 5 years of teaching experience. He is a senior software architect and Intel Software Technology expert. The teaching and research team of blockchain college led by him is mainly composed of master's and doctoral students who graated from Tsinghua University, Peking University and other well-known institutions
the team has rich practical experience in blockchain and has won many blockchain competitions.
bitcoin has the following advantages
First, it cannot be tampered with or forged. In real life, we may encounter counterfeit money, but in the bitcoin system, everything is recorded, so we don't need to worry about counterfeit moneyin the bitcoin network, it is guaranteed by the workload proof mechanism and the longest chain mechanism. In the bitcoin network, it is generally believed that the longest chain is the most correct one. It is precisely because this chain is responsible that it is very difficult to modify. Unless you have more than average computing power, there is no way to complete the tampering
In other words, if your private key is not lost, your bitcoin will always be yours and will not be tampered withthe main protocols are as follows: 1. IP internet protocol IP is the heart of TCP / IP and the most important protocol in the network layer. The IP layer receives the data packet from the lower layer (network interface layer, such as Ethernet device driver) and sends the data packet to the higher layer -- TCP or UDP layer; On the contrary, IP layer also transfers packets received from TCP or UDP layer to lower layer. IP packets are unreliable because IP doesn't do anything to confirm that the packets are sent in order or are not corrupted. IP packet contains the address of the host sending it (source address) and the address of the host receiving it (destination address). When high-level TCP and UDP services receive packets, they usually assume that the source address in the packet is valid. It can also be said that IP addresses form the authentication basis of many services, which believe that packets are sent from a valid host. IP confirmation contains an option called IP source routing, which can be used to specify a direct path between the source address and the destination address. For some TCP and UDP services, IP packets using this option seem to be delivered from the last system on the path rather than from its real location. This option exists for testing purposes, indicating that it can be used to spoof the system to make normally forbidden connections. Then, many services that rely on IP source address for confirmation will have problems and will be illegally intruded. 2. TCP if there are already sealed TCP packets in IP packets, then IP will "up" them to the TCP layer. TCP sorts packets and checks for errors, and realizes the connection between virtual circuits. TCP packets include sequence number and acknowledgement, so packets not received in order can be sorted, while damaged packets can be retransmitted. TCP sends its information to higher-level applications, such as telnet's server and client. Applications send information back to the TCP layer in turn, and the TCP layer sends them down to the IP layer, device drivers and physical media, and finally to the receiver. Connection oriented services such as Telnet, FTP, rlogin, X windows, and SMTP require a high degree of reliability, so they use TCP. DNS uses TCP (send and receive domain name databases) in some cases, but uses UDP to send information about a single host. 3. UDP is in the same layer as TCP, but it doesn't care about the order, error or retransmission of packets. Therefore, UDP is not used for connection oriented services that use virtual circuits. UDP is mainly used for query response oriented services, such as NFS. Compared with FTP or Telnet, these services need to exchange less information. Services that use UDP include NTP (Network Time Protocol) and DNS (DNS also uses TCP). Spoofing UDP packets is easier than spoofing TCP packets because UDP does not establish an initial connection (also known as handshake) (because there is no virtual circuit between the two systems), that is, UDP related services are at greater risk. 4. ICMP ICMP is located in the same layer as IP, which is used to transmit IP control information. It is mainly used to provide information about the path to the destination address. ICMP's "redirect" information informs the host of a more accurate path to other systems, while the "unreachable" information indicates that there is a problem with the path. In addition, if the path is not available, ICMP can terminate the TCP connection "gracefully". Ping is the most commonly used ICMP based service. 5. Port structure of TCP and UDP TCP and UDP services usually have a client / server relationship. For example, a telnet service process starts to be idle on the system, waiting for connection. The user uses the telnet client to establish a connection with the service process. The client program writes information to the service process, the service process reads the information and sends a response, and the client program reads the response and reports it to the user. Therefore, the connection is plex and can be used for reading and writing. How do multiple telnet connections between two systems confirm and coordinate with each other? A TCP or UDP connection uniquely uses the following four items in each message: the source IP address, the IP address of the sending packet. Destination IP address the IP address of the received packet. Source port the port of the connection on the source system. Destination port the port of the connection on the destination system. Port is a software structure, which is used by client program or service process to send and receive information. A port corresponds to a 16 bit number. Service process usually uses a fixed port, for example, SMTP uses 25, xwindows uses 6000. These port numbers are "well known" because these addresses and destination addresses are needed to communicate when establishing a connection to a particular host or service
reference model
TCP / IP protocol does not fully conform to OSI's seven layer reference model. The traditional open system interconnection reference model is a seven layer abstract reference model of communication protocol, in which each layer performs a specific task. The purpose of this model is to make all kinds of hardware communicate with each other at the same level. These seven layers are: physical layer, data link layer, network layer, transport layer, session layer, presentation layer and application layer. The TCP / IP communication protocol adopts a four layer hierarchical structure, and each layer calls the network provided by its next layer to fulfill its own requirements. These four layers are: application layer: the layer of communication between applications, such as simple e-mail transfer (SMTP), file transfer protocol (FTP), network remote access protocol (telnet), etc. Transport layer: in this layer, it provides data transmission services between nodes, such as transmission control protocol (TCP), user datagram protocol (UDP), etc. TCP and UDP add transmission data to the packet and transmit it to the next layer. This layer is responsible for transmitting data and determining that the data has been delivered and received. Interconnection network layer: it is responsible for providing basic packet transmission function, so that each packet can reach the destination host (but not check whether it is received correctly), such as Internet Protocol (IP). Network interface layer: manage the actual network media, define how to use the actual network (such as Ethernet, serial line, etc.) to transmit data
the reason why TCP / IP is a protocol family is that TCP / IP protocol includes TCP, IP, UDP, ICMP, rip, telnet FTP, SMTP, ARP, TFTP and many other protocols, which are collectively called TCP / IP protocol. Here we introce the English names and uses of some common protocols in the protocol family: TCP (Transport Control Protocol), IP (Internet Protocol), UDP (User Datagram Protocol), ICMP (Internet control message protocol) and SMTP (Simple Mail Transfer Protocol) Protocol SNMP (Simple Network Management Protocol) FTP (File Transfer Protocol) ARP (address resolution protocol) address resolution protocol from the perspective of protocol layered model, TCP / IP consists of four layers: network interface layer, inter network layer, transport layer and application layer. Among them: network interface layer, which is the lowest layer of TCP / IP software, is responsible for receiving IP datagrams and sending them through the network, or receiving physical frames from the network, extracting IP datagrams and giving them to the IP layer. The inter network layer is responsible for the communication between adjacent computers. Its functions include three aspects. 1、 After receiving the request, the packet is loaded into the IP datagram, the header is filled, the path to the destination machine is selected, and then the datagram is sent to the appropriate network interface. 2、 Processing input datagram: first check its validity, and then carry out pathfinding - if the datagram has arrived at the sink machine, remove the header and hand over the rest to the appropriate transport protocol; If the datagram has not arrived at the sink, the datagram is forwarded. 3、 Deal with path, flow control, congestion and other issues. The transport layer provides communication between applications. Its functions include: 1. Format information flow; 2、 Provide reliable transmission. In order to realize the latter, the transport layer protocol stipulates that the receiver must send back an acknowledgement, and if the packet is lost, it must be retransmitted. The application layer provides users with a set of common applications, such as e-mail, file transfer access, remote login and so on. Telnet uses telnet protocol to provide interfaces registered on other hosts in the network. Telnet session provides character based virtual terminal. File transfer access FTP uses FTP protocol to provide file function between machines in the network. We have learned the related concepts of OSI reference model. Now let's take a look at how TCP / IP protocol implements the network model compared with the seven layer protocol reference model. Layer functions in OSI: TCP / IP protocol family
application layer file transfer, e-mail, file service, virtual terminal, TFTP, HTTP, SNMP, FTP, SMTP, DNS, rip, telnet
presentation layer data format, code conversion, There is no protocol for data encryption
there is no protocol for session layer to release or establish contact with other nodes
the transport layer provides end-to-end interfaces TCP, UDP
the network layer selects routing IP, ICMP, OSPF, BGP, IGMP, ARP, RARP for data packets
the data link layer transmits addressable frames and error detection functions slip, CSLIP, PPP, MTU
the physical layer transmits data iso2110 and IEEE802 on the physical media in the form of binary data. Ieee802.2
data link layer includes hardware interface and protocols ARP and RARP