January 23, 2019 in the afternoon, I was crazy company of line with the code, the code immersed in my world, is enjoying one line lambda expression he had just written, and suddenly micro-channel uploads a message to his girlfriend.
So, I open my terminal, ready to ping it and see how matter in the end:
➜ mhcoding ping cn.bing.com
PING cn.bing.com (127.0.0.1): 56 data bytes
64 bytes from 127.0.0.1: icmp_seq=0 ttl=64 time=0.046 ms
64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.091 ms
64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.098 ms
复制代码So, I would reply to his girlfriend on a micro letter:
I came home from work at night, before I take off my shoulder bag, girlfriend ran quickly came to me.
DNS
DNS, Domain Name System is an acronym, translated into the domain name system. It acts as a distributed database of domain names and IP addresses will be mapped each other, it can make it easier to access the Internet.
DNS most important role is to translate domain names into ip address.
IP addresses
IP address is the IP Address acronym refers to Internet Protocol Address (English: Internet Protocol Address, also translated as the Internet Protocol address). IP address is a uniform address format of the IP protocol provides, assign it a logical address for each network on the Internet and each host in order to mask the differences in the physical address.
Each computer on the Internet is assigned an IP address.
IP addresses are used to computers on the Internet a number. Daily situation we see is we need to have IP addresses can not communicate on each networked PC.
An IP address is a 32-bit binary number, it is generally divided into four "8-bit binary number" (i.e. 4 bytes). IP addresses are typically in the form of "dotted decimal" expressed as (ABCD) of. Such as: 208.80.152.2
domain name
Domain name, this is a lot of people are familiar with the concept, we in most cases, when visiting a site in the browser, all accessible through the domain name.
The Internet domain name is separated by a series of dot characters a computer or group of computers for identifying the orientation of the electronic computer in data transmission.
Domain name can be a generation of IP addresses, the aim of which is to facilitate memory.
For example, wikipedia.org is a domain name, and IP address 208.80.152.2, respectively. One can directly access wikipedia.org instead of IP addresses, and Domain Name System (DNS) will facilitate to convert it to identify the IP address of the machine.
Thus, one need only remember wikipedia.org this string of characters with a special meaning, without the need to remember no figures meaning.
Domain names, IP and DNS
In real life, we may often need to find people by phone, each access network has its own unique telephone number.
Sometimes, we want to fight a company's customer service phone, such as the Industrial and Commercial Bank of customer service you want to call and want to check account balances. But we do not know the specific numbers, we can call 114, tell them what you want to call ICBC phone. Then the customer service 114 phone inquiries will help you to Industrial and Commercial Bank, and to help you to automatically transferred to the Industrial and Commercial Bank of customer service calls.
This process is and domain name, the relationship between IP addresses and DNS more like a.
每一台接入网络的电话 -> 每一台接入网络的计算机
工商银行 -> 域名
电话号码 -> ip地址
114咨询台 -> DNS
复制代码With DNS, we do not need to remember multiple IP addresses for each site, we need only road to the site domain name on it. Just as we do not care about ICBC's customer service phone, we need to know we are looking for ICBC on it.
And, for a Web site, a domain name will correspond to its numerous IP addresses. Load balancing will be formulated by other means. Like the Industrial and Commercial Bank customer service center also has a lot of extension is the same reason.
Some network operators for certain purposes, may restrict certain users access to a specific site, and is the most common means of limiting DNS pollution and DNS hijacking.
Under normal circumstances, when we visit a domain name, the page will jump to fail, but if you climb the wall, you can normally access. For example, so-called qiang.
There is also a typical scenario, when our broadband arrears, when visiting a website, automatically jump to the operator's website, prompting recharge.
It's all rigged operators on DNS. Its purpose is to let the domain name can not be resolved to the normal IP address.
And during this visit will be unable to be found by ping, cn.bing.com be parsed DNS to 127.0.0.1. This is the direct cause of reason can not access bing.
127.0.0.1 is the loopback address, referring to the local machine, usually used for testing.
DNS poisoning
Domain server cache poisoning (DNS cache pollution), also known as cache poisoning the domain name server (DNS cache poisoning), refers to the number of domain name server packages or deliberately created inadvertently produced, the domain name does not refer to the correct IP address.
The way it works is: As usual DNS queries without any authentication mechanism, and DNS query protocol is usually based on the UDP is a connectionless unreliable, so the DNS queries are vulnerable to tampering, intrusion by UDP DNS on port 53 queries request detection, and once found matching the keyword is immediately disguised as a target domain name resolution server (NS, Name server) returns a false result to the inquirer.
DNS poisoning refers to the address of the user accessing a domestic server (non-DNS) to monitor user access has been marked address, the server disguised as a DNS server sends back the wrong address to a user's behavior. In order to reduce traffic on the network, usually outside of the domain name server will temporarily stores the data until the next time when there are other machines required a name, the service can be provided immediately. Once the cache is related to the local name server domain is contaminated, it will guide the computer in the domain to the wrong server or server URL.
Simply put, DNS pollution refers to disguise himself as a DNS server, after checking the user access to certain websites, the domain name resolves to the wrong IP address.
DNS hijacking
DNS hijacking, also known as domain name hijacking, means intercepting DNS requests in the hijacking of network-wide analysis of domain name requests, the request outside the scope of the review of the release, otherwise it returns false IP address or do nothing in response to the request to lose, the effect is not access or access to specific network is a fake URL.
The difference between DNS pollution and DNS hijacking
DNS hijacking is hijacking the DNS server, and then modify its analytical results.
DNS poisoning is certain domestic servers for DNS queries intrusion detection, discovery request matches with the blacklist, the server will masquerade as a DNS server returns a false result to the inquirer. It uses the UDP protocol is a connectionless unreliable.
One is hijacked DNS server, a DNS server is disguised. The result is an incorrect IP address is returned.
How to solve pollution and DNS hijacking
For DNS hijacking, you can manually replace the third-party DNS server to resolve public DNS.
Public DNS is a free DNS for the mass of Internet infrastructure services. After replacing the DNS server addresses to the public DNS, it can accelerate to a certain extent, DNS speed to prevent DNS hijacking, strengthen Internet security, can also block most of the carrier's advertising.
DNS is commonly used in public the following figure:
For DNS poisoning, it can be said, relying solely on the individual user is difficult to solve the set, you can usually use VPN or remote domain name analytic solutions.
It will be hung up on how to access
www2.bing.com or www4.bing.com
Second, mandatory binding host
Users only need to temporarily modify the host and then wait for the next Microsoft server recovery after deleted. That forced IP address specified cn.bing.com points.
13.107.21.200 cn.bing.com
If the revised browser still does not open, please reboot the system directly, reboot and try again to open the Bing search to see if normal access.
Third, modify the DNS server
The modified DNS public DNS, such as 8.8.8.8 or 114.114.114.114.
Reference: https: //laod.cn/news/cn-bing-com-404.html
Follow-up events
January 23 afternoon, users found Microsoft's search engine Bing (Bing) can not access the fault occurs. After opening the show, "Can not access this site."
January 24, Microsoft spokesman has said the reporter replies, "ongoing investigation" and "We are actively respond to determine the next relevant measures."
January 25 morning, a Microsoft spokesman said the reporter replies, "We will be confirmed before the site is not accessible in China, but is now back to normal." However, Microsoft did not disclose the reasons previously not normally access.
Focus of this paper is to analyze the cause will be not be a normal visit, and the domain name, DNS and other not-depth introduction and expansion, if interested readers back will continue to unfold one by one introduction.