Let the mine dig more

1.

You can't dig in a day. It takes 2000 years

the global unified computing difficulty of bitcoin is 2621404453 (expected to change in two days). It takes more than 2000 years for a 2.5GHz CPU to work out a bitcoin

in order to make the graphics card fully loaded for a long time, the power consumption will be quite high, and the electricity bill will be higher and higher. Many professional mines at home and abroad are operated in areas with extremely low electricity charges, such as hydropower stations, while more users can only mine at home or in ordinary mines, so the electricity charges are not cheap. Even in a certain residential area in Yunnan, there was a case of crazy mining, which led to a large area trip of the residential area, and the transformer was burned

extended data:

bitcoin network generates new bitcoin through "mining". In essence, the so-called "mining" is to use computers to solve a complex mathematical problem to ensure the consistency of bitcoin network distributed accounting system

bitcoin network will automatically adjust the difficulty of mathematical problems, so that the whole network can get a qualified answer about every 10 minutes. Then bitcoin network will generate a certain amount of bitcoin as block reward to reward the person who gets the answer

when bitcoin was born in 2009, block rewards were 50 bitcoins. Ten minutes after its birth, the first 50 bitcoins were generated, and the total amount of money at this time is 50. Then bitcoin grew at a rate of about 50 every 10 minutes. When the total amount reaches 10.5 million (50% of 21 million), the block reward will be halved to 25

when the total amount reaches 15.75 million (5.25 million new output, i.e. 50% of 1050), the block reward will be further halved to 12.5. The monetary system used to have no more than 10.5 million in four years, after which the total number will be permanently limited to about 21 million

2. Direct code solution
SSC install Center
center vars

3. The implementation plan of "Research on improving primary school students' computational ability" I. background of the project
1. Cultivating students' computational ability is an important task of primary school mathematics teaching and an important foundation for students to learn mathematics in the future. According to the quality analysis of usual testing and final examination, students' computing ability is generally low, which undoubtedly causes great obstacles to students' learning and development. In order to quickly and effectively improve students' computing ability, better develop students' thinking, and improve the quality of mathematics teaching in a large area, it is necessary to strengthen the teaching of calculation as a breakthrough in primary school mathematics teaching
2. Through the research of this topic, we should strive to improve students' computing ability, cultivate their oral, mental and written abilities, and encourage students to graally like mathematics and become interested in calculation in lively and relaxed learning. So as to improve students' academic performance and lay a solid foundation for students' future study< Second, the goal of the research is to find out the reasons for the slow speed and low accuracy of students' mathematical calculation< Looking for teaching breakthrough and teaching training methods that can improve students' mathematical calculation speed and accuracy: (1) strengthen students' oral calculation training by taking oral calculation ability training as a breakthrough 2) Control a certain amount of training to cultivate students' sense of number 3) While paying attention to the training of students' thinking ability, we should pay attention to the training of students' mathematical calculation, grasp the basis, highlight the pertinence, find the regularity, and properly integrate< Third, research measures
1
"in order to cultivate students' computational ability, we should pay attention to the basic training of oral arithmetic, insist on regular practice, and graally achieve proficiency." This is the requirement of mathematics curriculum standard. In the process of teaching, we should organize teaching and training in a planned, step-by-step and purposeful way, such as listening to arithmetic, reading cards and oral arithmetic, reading questions and calculating silently, and repeatedly emphasize that the first is correct and then fast
2. Strengthen basic knowledge and improve written calculation ability
in calculation teaching, oral calculation is the basis of written calculation, while written calculation is the key. Written calculation plays an extremely important role in primary school mathematics teaching. No matter how advanced the technology is in the future, the ability of written calculation is always a necessary ability for primary school students
(1) to enable students to understand the basic knowledge of mathematics and master skills is the primary condition for the formation of computational ability
each calculation is based on the corresponding concepts, rules, properties, formulas and other basic knowledge. If students don't understand these basic knowledge correctly and master them thoroughly, they can't calculate. Only after students understand and master the relevant operation properties, laws and skills, can they apply these knowledge in specific calculation to seek simple and reasonable methods, improve the accuracy of calculation and speed up calculation
(2) strengthening practice and skill training is the key to the formation of students' computing ability
for example, in the calculation of four items of scores, some students often encounter the situation that the calculation method is correct but the calculation result is wrong. The reason for the error lies in the basic skills such as score rection, general score or mutualization; Another example is the division of decimals, especially when the divisor is a decimal. The mistake is that when the divisor becomes an integer, the divisor does not expand the same multiple at the same time, resulting in a wrong quotient. So we should strengthen the training of basic calculation skills in calculation practice
(3) memorize common data to improve the calculation speed
in the four arithmetic operations, if students memorize some common data, it will not only help students to achieve the requirements of "correct and rapid", but also help them master the skills of calculation. For example: special data with sum and proct of whole hundred and thousand (for example: 75 + 25 = 100 + 25) × 4=100 125 × 8=1000 The proct of the approximate value of PI 3.14 with one digit and the proct with several common numbers 12, 15, 16, 25 and 36; The denominator is the decimal value of the simplest fraction of 2, 4, 5, 8, 10, 16, 20 and 25, that is, the interaction of these fractions and decimals
the results of the above numbers, whether in daily work or in real life, are used very frequently. After mastering and remembering them, they can be transformed into abilities and proce high efficiency in calculation
3
after mastering the calculation method, students tend to deal with the boring calculation, resulting in more calculation errors. At this time, the proper development of some computing competition activities, often can better mobilize the students' learning initiative, improve the interest in computing, and achieve the purpose of improving the accuracy of computing. This semester, I plan to carry out two calculation competitions in the class, in order to improve the students' interest in calculation and improve the accuracy of calculation. After the competition, pay attention to sort out the students' mistakes, analyze and classify them, and then make targeted remedies, so as to clear the obstacles for improving the students' computing ability
4. Encourage students to have a pleasant learning experience
teachers should encourage students to make mistakes e to carelessness. In the usual homework correction, we should affirm its strengths, enhance self-confidence, put forward ardent hope, and urge it to correct its shortcomings< 5. Expected effect
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2. Cultivate students to participate in the derivation of rules and formulas, and truly clarify the calculation
3. Help students memorize common data and improve the calculation speed
4. Pay attention to the analysis of wrong cases and suit the right medicine to the case
5. Cultivate students' habit of checking calculation consciously and correcting mistakes independently
6. Cultivate students' habit of summarizing and reflecting< 6. Research steps of the project
the project started in February 2014 and ended in June 2014
the first stage is to formulate the implementation plan of the research project and write the experimental plan of the project
the second stage: implementation stage (February 2014 to June 2014)
the third stage: writing the final Research Report of this topic. In short, in the process of research, I will strive to make plans, implementation, feedback and summary, so as to ensure the smooth progress of the research and receive actual results.

4. Eth0 refers to one of your network cards or the first network card. It means to stop down. Ifconfig means to list network information
this command means to disable the etho network card

5. Moore Manor is not mining and farming, if you want to farm, you can play happy little farmer game.

6. There is no guarantee for this. After all, if something happens one day, he will seal off the platform directly, and he will get nothing.

7. Board game checked, it seems that the trigger of emperor 2 can not be set like that
allied forces can also command by unlocking the lock. The villagers said they had never tried
the compromise is to set up more resources in other people's territory, the computer will automatically proce them, and the farmers will go to mine them, but if they don't finish mining, the dedicated villagers will not stop.

8. What's this?

10. The key to the success of DDoS is to find a large number of computers with weak security measures on the Internet. Therefore, the frequent use of security detection tools to detect the network and the host, find out the existing security risks and give the corresponding countermeasures, can rece or even avoid the possibility of the host being used as a puppet machine by hackers. The security scanning tool can detect and delete the software installed by hackers to attack DDoS. Security scanning tools should be upgraded with the evolution of attack methods
2.1.2 use NIDS and sniffer
when the system receives suspicious traffic with unknown address, NIDS (Network Intrusion Detection Systems) will send out alarm signals to remind the system administrator to take timely countermeasures, such as cutting off the connection or reverse tracking. The security policies or rules of NIDS should be up-to-date and contain the characteristics of the latest attack technology
sniffer can be used to identify network attacks at the network level and become the source of NIDS original detection information. For example, when a hacker modifies the data part of an IP packet to contain some hidden information, the sniffer can detect the information and provide it to the relevant personnel for analysis, which becomes the basis for blocking, diverting malicious traffic or tracing the hacker
2.1.3 update system patches in time
the existing operating systems have many vulnerabilities, which makes it easy for hackers to find the back door, so downloading and updating system patches in time is also very important to resist hackers<

2.2 defense on network devices
defense on a single machine is mainly to rece the possibility of being used as a puppet machine, and taking preventive measures on the router is the key to resist DDoS. Here we take Cisco router as an example to analyze the methods to prevent attacks:
2.2.1 check every packet passing through the router
in the CEF (Cisco express forwarding) table of the router, If there is no route for the source IP address of a packet among all the routing items of the network interface to which the packet arrives, the router will discard the packet. For example, the router receives a packet with a source IP address of a.b.c.d. if no route is provided for the IP address of a.b.c.d in the CEF routing table (that is, the route required for reverse packet transmission), the router will discard it
2.2.2 set the syn packet traffic rate
many DDoS attacks are in the form of SYN Flood attack, so it is necessary to limit the syn packet traffic rate on the router. When using this method, we must ensure the normal operation of the network in order to avoid large errors
rate limit output access group 153 45000000 100000 form action
transfer exceeded action drop
rate limit output access group 152 1000000100000 form action
transfer exceeded action drop
access list 152 permit TCP any host EQ www
access list 153 permit TCP any host EQ www established
2.2.3 on the side Deployment policy on border router
network administrator can deploy filtering policy on Border Router:

ISP border router should only accept communication whose source address belongs to client network, while client network should only accept communication whose source address is not filtered by client network< Access control list of ISP side border router:
access list 190 permit IP client network client network mask any
access list 190 deny IP any [log]
interface internal network interface network interface number
IP access group 190 in
access control list of client side border router:
access list 187 deny IP client network client Client network mask any
access list 187 permit IP any
access list 188 permit IP client network mask any
access list 188 deny IP any
interface external network interface network interface number
IP access group 187 in
IP access group 188 out
2.2.4 use car to limit ICMP packet flow rate
car (cont Rol access rate, which can be used to limit the packet traffic rate, is a tool to achieve QoS (quality of service). It can be used to limit ICMP packets to prevent DDoS
rate limit output access group 2020 30000000 512000 786000 form action
transmit exceeded action drop
access list 2020 permit ICMP any any echo reply
2.2.5 use ACL to filter all addresses listed in RFC 1918
ACL (access control list) is a way for router to filter specific target address, source address, destination address, destination address, destination address, destination address and destination address It can be used to filter out all the addresses listed in RFC 1918, that is, private IP addresses (10.0.0.0/8172.16.0.0/12, 192.168.0.0 / 16)
IP access group 101 in
access list 101 deny IP 10.0.0.0.255.255 any
access list 101 deny IP 192.168.0.0.0.255.255 any
access list 101 deny IP 172.16.0.0.15.255.255 any
access list 101 permit IP any
2.2.6 collect evidence
log server can be established for router, It is recommended to use high-speed computers such as Sun workstation or Linux to capture data packets. Common packet capture tools include tcpmp and snoop. The basic syntax is:
tcpmp - I interface - s 1500 - W capture_ file
snoop -d interface -o capture_ file -s 1500