Reflective ddos attack principle ddos attack reflexivity

The full name of DDOS is DistributedDenialofservice, commonly known as flood attack. Many DOS attack sources attack a server together, forming a DDOS attack. The earliest DDOS attack can be traced back to 1996, which began to appear frequently in China in 2002 and began to take shape in 2003.

-The above is quoted from Interactive Encyclopedia.

DDoS attack means is an attack method based on traditional DoS attack. A single DoS attack is generally one-to-one, and the effect is obvious when the target CPU is slow, the memory is small or the network bandwidth is small.

With the development of computer and network technology, the processing capacity of computer has increased rapidly, and the memory has also increased greatly. At the same time, the emergence of Gigabit network makes DoS attack more difficult-the target's "digestion ability" to malicious attack packets has been strengthened a lot.

For example, your attack software can send 3000 attack packets per second, but my host and network bandwidth can handle 10000 attack packets per second, so the attack will not have any effect.

At this time, Distributed Denial of Service Attack (DDoS) came into being. If you know about DoS attack, its principle is simple.

If the processing power of computers and networks is increased by 10 times, it is no longer possible to attack with one attack plane, then what should an attacker do with 10 attack planes at the same time? 100? DDoS is to use more puppet planes to launch attacks and attack victims on a larger scale than before.

Are the air flow value and intake air temperature low?

Theoretically, the reasons why the air flowmeter shows low liquid level are as follows:

(1) There is leakage in the metering system, and it is the positive (high) pressure side of the air flowmeter or the positive (high) pressure side of the pressure guide pipe, or the leakage at the positive pressure side is more serious than that at the negative pressure side;

(2) The heights of condensate columns in the two pressure pipes are not equal, there is gas in the positive pressure pipe or the liquid level in the negative pressure pipe is higher than that in the positive pressure pipe (the liquid column in the positive pressure pipe is lower than that in the negative pressure pipe), and the additional error caused by static pressure makes the flow indication value low;

(3) The gas in the positive pressure chamber of the differential pressure transmitter is not completely exhausted. Open the vent hole of the positive pressure chamber and tighten it after seeing the liquid flow out;

(4) The balance valve in the three-valve group is not closed tightly or leaks after tightening, so it needs to be closed loosely or replaced.

(5) If the differential pressure transmitter or secondary instrument fails, it is necessary to recalibrate the differential pressure transmitter or secondary instrument;

(6) Deformation of the air flow meter —— The air flow meter shows that it moves to the negative pressure side, and the distance between the flow necking and the air flow meter is farther than that installed below, resulting in an increase in the measured value of the back pressure hole pressure of the air flow meter. Resulting in a decrease in version differences;

(7) The direction of the air flowmeter is reversed, and the distance between the flow necking and the air flowmeter is far from the correct installation, which leads to the pressure measurement value of the pressure tap after the air flowmeter increasing and the pressure difference decreasing. Need to be reinstalled.

(8) If it is a pneumatic instrument (in this case, an electric instrument is used), it is also necessary to check whether the output pipeline leaks.

Generally, the results can be detected according to the first five reasons. After the problem is solved, everything works normally. If it is still abnormal, the last two reasons, due to normal production, can not stop steam supply, can not be checked. Only when the steam supply is stopped can the air flowmeter be disassembled for inspection.

After the steam supply stops, remove the orifice plate for inspection. The air flowmeter is not installed backwards, but to the negative pressure side to the left (convex). The reason is that there is condensed water in the pipeline from the air flowmeter to the power station (gas supplier) when the equipment is started to send steam. Improper handling (drainage does not open the inverted valve, and the valve is opened too fast) leads to the arrival of water hammer. Therefore, the measured pier value is low. Check the original records of process operation. After the overhaul, the engineering quantity is reduced by about 18% compared with that before the overhaul. Re-process the air flowmeter according to the original processing drawing. After the air flow meter is updated, it will resume normal operation.

What is the maintenance work of air flowmeter?

(1) First, disassemble the air flow meter for comprehensive cleaning, including the cleaning of throttling parts, and the removal and dredging of deposits in the annular cavity, pipeline and pressure guide pipe. In the process of cleaning the throttle, we should pay attention to the use of soft materials to ensure that the end face and edge are not scratched.

(2) Check the geometry and size of the air flowmeter:

① Judge the surface roughness of the inspected section by visual inspection.

② Check edges G, H and I with magnifying glass and reflected light method. If there is no light emission, the edge is considered sharp.

(4) Use template ruler, etc. Check the flatness of the upstream end face. Put the air flowmeter on the flat plate, with the inspected end face facing upwards, gently lean against the inspected end face with a template ruler with an appropriate length, check the flatness of the end face with the straightness of the diameter, turn the air flowmeter to find out the width of the Z gap along the diameter, and measure the height h.hO.002(D-d) with a block gauge (or feeler gauge) to be qualified.

(3) After inspection, it can be handled according to the size deviation of the air flowmeter. If the deviation is large, it can be reworked on the basis of the original air flowmeter to form a new usable air flowmeter, and then redesigned to continue to use the air flowmeter by adjusting the secondary instrument. Otherwise, the air flow meter should be purchased again.

(4) The air flowmeter is a concealed project (it cannot be checked from the outside after construction). Maintenance records and archived data must be modified.

202 1 protect network security events?

Data leakage incident?

It is suspected that more than 200 million pieces of domestic personal information are sold in foreign dark network forums.

On October 5th, 65438/kloc-0, a foreign security research team, Cyble, discovered that several posts were selling personal data related to China citizens. After analysis, these data may come from social media such as Weibo and QQ. The total number of records related to China citizens in several posts discovered this time exceeds 200 million.

The first personal information protection case in China, where the Civil Code was applied, was pronounced.

65438 10/8, Hangzhou internet court publicly heard and pronounced the first case of personal information protection applying the civil code in China. Defendant Sun publicly illegally bought and sold more than 40,000 pieces of personal information on the Internet without the permission of others, and there was a long-term risk that the information of relevant personnel was infringed. He was sentenced to compensate the illegal income of 34,000 yuan and publicly apologized.

Suspected data leakage in a domestic bank16.79 million.

On October 8th, 65438/kloc-0, someone posted on a foreign forum to sell16.79 million pieces of data of a domestic bank, and released some data samples, including name, gender, card number, ID number, mobile phone number, city, contact address, work unit, postal code, work phone number, home phone number, card type, issuing bank, etc.

Online lending companies were fined 3.2 million for infringing personal information.

15 10/5, China Judgment Document Network published a judgment, and Beijing Company and Xian Moumou sold their personal information including their names, ID numbers and mobile phone numbers to several downstream companies without the consent of the victims, committing the crime of infringing citizens' personal information, and were fined 3.2 million yuan. Buying a house involves many well-known companies such as Ping An Pratt & Whitney, Paipai Loan, You and I Loan.

30 people in Danyang, Zhenjiang sold 600 million pieces of personal information and made a profit of more than 8 million yuan.

654381On October 24th, Zhenjiang Danyang police cracked a case of infringing citizens' personal information, which was supervised by the Ministry of Public Security, involving more than 10 provinces and cities, and arrested 30 suspects. The gang used overseas chat tools and blockchain virtual currency to receive and pay, * * * sold more than 600 million pieces of personal information and earned more than 8 million yuan in illegal income.

After CCTV exposed App to eavesdrop on private message voice, the recording continued.

On June 365438+1October 3 1 day, CCTV program experts made a 2-second voice by simulating the "App eavesdropping test program". When the hand was released, the recording continued, producing a sound of 120 seconds, which proved that eavesdropping was possible when the test program was placed in the foreground. In addition, after comparative experiments, it is found that the recording can still last for a period of time when the test program returns to the background or the screen of the mobile phone is locked.

Xiaoyao.com in Xishanju was attacked and its data was leaked.

On March 2, Xishanju Game announced that Xishanju products were repeatedly attacked by criminals' DDos and invaded by servers, resulting in the leakage of some user accounts and encrypted plaintext passwords. The official suggested that the short password with low security level should be modified as soon as possible.

The first case of obtaining personal information by using WeChat powder scanning software in China was pronounced.

On March 3rd, Nantong Tongzhou Public Security Bureau pronounced a verdict on the first case of illegally obtaining WeChat user information by using WeChat "Clean Powder" software in China. In order to "slim down" the WeChat address book, the victim user scanned the QR code of "Clear Powder", but his personal information was leaked. Eight defendants illegally made more than 2 million yuan by reading and selling WeChat group chat QR codes.

3 15 exposes chaos such as face information abuse and resume disclosure.

On March/KOOC-0/5, CCTV 3/KOOC-0/5 exposed three cases involving personal information security: merchants installed cameras to record customers' facial information, and many stores * * * enjoyed and comprehensively quoted prices; The resumes of platforms such as Zhaopin recruitment and hunting can be downloaded at will, and a large number of resumes flow into the black market; Many mobile phone cleaning apps developed for the elderly constantly obtain mobile phone information in the background and push content with deceptive routines.

CITIC Bank was fined 4.5 million yuan for leaking customer information.

On March 19, the ticket issued by the Consumer Protection Bureau of the China Banking Regulatory Commission showed that CITIC Bank was fined 4.5 million yuan. It is reported that the ticket is suspected that in May 2020, the talk show artist pool reported the punishment result of CITIC Bank's illegal provision of its bank flow information.

Network attack event

Many industries are infected with the virus.

65438+1October 13, many domestic security vendors detected a large-scale outbreak of the worm in China, involving government, medical care, education, operators and other industries, and most of the infected hosts were financial management-related application systems. The infected host shows that all non-system partition files have been deleted, causing irreparable losses to users.

Sms phishing attacks against rural credit cooperatives and city commercial banks

Since the Spring Festival, a series of security incidents have occurred in many cities across the country, in which customers are tricked into clicking on the links of phishing websites and stealing funds on the grounds that mobile banking is invalid or expired. Sky Friends found that after February 9, a large number of phishing websites were registered and put into use. The domain name of phishing websites is the customer service telephone number+letters of financial institutions such as rural credit cooperatives and city commercial banks, or the domain name similar to that of financial institutions, and most of them are registered and hosted by overseas domain name registrars.

DDoS attacks surged during the Spring Festival.

On February 22nd, CITIC Construction Investment Lab released a report on DDoS attacks during the Spring Festival. According to the report, during the Spring Festival, Chianxin satellite-orbit DDoS observation system observed 659 12 amplified DDoS attacks, involving the attacked IP of IP57096. Compared with the week before the Spring Festival, the number of DDoS attacks increased by about 25%, and the number of attacked IP increased by 37%.

App infringes on user rights?

Aiming at the problem that App infringes on users' privacy and safety, the Ministry of Industry and Information Technology has established a national App technology testing platform to conduct technical testing on popular apps on the shelves in China. If the App does not meet the requirements, it will require rectification first. Apps that have not passed the rectification or have not been rectified as required will be directly removed.

19 10/9, the Ministry of Industry and Information Technology removed 12 apps, including Xuebao and Red Man Live. , involving illegal collection of user information, excessive demand for user rights, deception and misleading users to download. (On June 5438+February 2, 2020, the Ministry of Industry and Information Technology notified 63 illegal apps, and 12 failed to complete the rectification as required)

65438+1On October 22nd, the Ministry of Industry and Information Technology notified the first batch of 157 apps that infringed users' rights and interests in 20021year, including Mango TV, Yonghui Life and Zanthoxylum bungeanum. , which involves illegally collecting personal information, forcing users to request permission frequently and excessively, and forcing users to use targeted push. On February 3, the Ministry of Industry and Information Technology removed 37 unreformed apps, including Yilong Hotel, Dongfeng Tourism, and an auto repair.

On February 5, the Ministry of Industry and Information Technology reported that 202 1 the second batch of 26 apps had irregularities, including QQ input method, UC browser and ink weather. , involving illegal collection of personal information, excessive request for permission, cheating and misleading users to download. On February 10, 10 apps that were not rectified were taken off the shelves, including Xiao Zhi classmate, music bar and kk keyboard.

12 In March, the Ministry of Industry and Information Technology notified the third batch of apps 136 in 20021year, which infringed on users' rights and interests, including Cheetah Cleanup Master, Yuepao Circle and Tianya Community. , involving frequent self-activation and associated activation, illegal collection and use of personal information and other issues.

On March 16, the Ministry of Industry and Information Technology severely investigated and dealt with the violation of "APP illegally collecting personal information of the elderly" at the party on March15, and asked the main application stores to give four apps, namely, memory optimization master, smart cleaning master, super cleaning master and mobile phone housekeeper pro.

Will rain affect the mobile phone traffic signal?

it will be

For electromagnetic waves, rain will attenuate them, which is called rain attenuation, but electromagnetic waves with different frequencies have different penetration rates to rain. Cell phone signals use ultra-high frequency radio, which belongs to electromagnetic waves and propagates directly in the air without ion layer reflection. Because the air humidity is high when it rains, the greater the frequency of electromagnetic waves, the easier it is to be absorbed, which weakens the signal strength. So the cell phone signal will get worse in rainy days.