In the world of computer security, a denial-of-service attack (DoS attack) is defined as an attempt to make a computer resource run out of the resources and make it unavailable to its intended users.在世界上的計算機安全，拒絕服務攻擊（ DoS攻擊）的定義是企圖使計算機資源枯竭的資源並使其無法使用它的用戶。 The main aim of Dos is to prevent an Internet site or service from functioning efficiently or at all, temporarily or indefinitely.的主要目的多是為了防止一個互聯網站點或服務的運作效率，或在所有暫時或無限期。

We can understand by its meaning that “Denial or service” occurs when either the service is not available or it can not handle any further request.我們可以理解其含義是“拒絕服務”時，就會發生或者服務不存在或無法處理任何進一步的請求。 While using some of the services on雖然使用的一些服務 yahoo messenger we get a message “Service temporarily not available” , the reason could be there is too much load on the server and it can not handle any further request.雅虎我們得到的訊息“服務暫時無法使用”的原因可能是有太多的負載服務器，它不能處理任何進一步的請求。

What is Denial of Service ?什麼是拒絕服務？

In Dos, the attacker attempts to prevent regular users from accessing the site or service.在多斯桑托斯，攻擊者企圖阻止正常用戶訪問該網站或服務。 By attacking your site the attacker might prevent you from accessing resources like email and even disabling the loading of the site.通過您的網站攻擊，攻擊者可能會阻止您訪問資源，例如電子郵件，甚至停用裝載的網站。 In short you service is not able to take further request and hence unavailable.總之您服務是無法採取進一步的要求，因而無法使用。

Why Denial of Service occur ?為什麼拒絕服務攻擊發生的？

Routers, servers and network services are made to handle a finite amount of resources at any given time depending on the hardware configuration and power of that machine.路由器，服務器和網絡服務，以處理有限的資源數額在任何特定時間取決於硬件配置和電源的機器。 If the limit of request surpasses it will start rejecting any further request.如果限制的請求超過將開始拒絕接受任何進一步的請求。 So an attacker can just overload the server with such huge amount of request that server crashes or its not free to take any further request.For an example, An attacker can spam you inbox with so many emails that you cross your storage limits ie your inbox is full and you don’t get any more emails.所以攻擊者只需在服務器超載等大量的要求，服務器崩潰或其不得隨意採取任何進一步的request.For一個例子，攻擊者可以你的收件箱的垃圾郵件有這麼多的電子郵件，你跨您的存儲限制即您的收件箱是充分和你沒有得到任何更多的電子郵件。

DOS Denial司拒絕

Features of Dos Attacks特徵的DoS攻擊

• Disrupting service to a specific system or person.中斷服務的具體制度或人。
• Disrupting connections between two machines.擾亂之間的連接兩台機器。
• Flooding of network hence rejecting any further request.網絡驅因此拒絕任何進一步的要求。

Dos can be very powerful tool in the hands of a smart attacker. Dos可以非常有力的工具手中的一個聰明的攻擊者。 There are types and ways to prevent it.有種類和方式，以防止它。 We have talked about that in the我們已經談到，在 “Types of Dos Attacks and Introduction to DDos” “類型的拒絕服務攻擊和分佈式拒絕服務簡介” . 。 I hope you enjoyed the post我希望你喜歡的職位

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