Is a DDOS attack a type of DOS attack?

Is a DDOS attack a type of DOS attack?

DDOS attack is a type of DOS attack. DDOS distributed denial of service attack refers to using client or server technology to unite multiple computers as an attack platform to launch DDoS against one or more targets. attack, thus exponentially increasing the power of denial of service attacks.

Common DOS attack methods

1. SYN FLOOD

Using the server’s connection buffer (Backlog Queue) and special programs, Set the TCP Header to continuously send multiple TCP connection requests with only the SYN flag to the server. When the server receives it, it considers it to be a connection request that has not been established, so it establishes sessions for these requests and queues them in the buffer queue.

If your SYN request exceeds the limit that the server can accommodate and the buffer queue is full, the server will no longer accept new requests. Connections from other legitimate users are rejected. You can continue to send your SYN requests until the buffer is full of your requests with only SYN tags.

　2. IP spoofing DOS attack

This attack uses the RST bit to implement. Assume that a legitimate user (1.1.1.1) has established a normal connection with the server. The attacker constructs attack TCP data, disguises his IP as 1.1.1.1, and sends a TCP data segment with the RST bit to the server. . After receiving such data, the server thinks that the connection sent from 1.1.1.1 has an error, and will clear the established connection in the buffer. At this time, if the legal user 1.1.1.1 sends legal data again, the server will no longer have such a connection, and the user must start from scratch to establish a connection.

During the attack, a large number of IP addresses are forged and RST data is sent to the target to prevent the server from serving legitimate users.

　3. Bandwidth DOS attack

If your connection bandwidth is large enough and the server is not very large, you can send requests to consume the server's buffer and consume the server's bandwidth. This kind of attack is more powerful when there are more people. When combined with SYN to implement DOS, it is extremely powerful. It's just a rudimentary DOS attack.

4. Self-consuming DOS attack

This is an old-fashioned attack method. I say old-fashioned because old-fashioned systems have their own bugs. Such as Win95 (winsock v1), Cisco IOS v.10.x, and other outdated systems.

This kind of DOS attack is to make the requesting client IP and port the same as the IP port of the host and send it to the host. Causes the host to send TCP requests and connections to itself. Such host vulnerabilities will quickly consume resources. Directly leading to a crash. This disguise is still a huge threat to some identity authentication systems.

The most important means of implementing DOS attacks above are to construct the required TCP data and make full use of the TCP protocol. These attack methods are all based on TCP. There are other means of DOS attacks.

　5. The hard disk of the server is filled up

Usually, if the server can perform write operations without restrictions, it can become a way for the hard disk to be filled up and cause DOS attacks, such as:

Send spam. Generally, the company's server may put the mail server and WEB server together. Vandals can send large amounts of spam, which may sit in a mail queue or bad mail queue until the mailbox is burst or the hard drive is filled.

Let the log records be full. Intruders can construct a large number of error messages and send them out. The server records these errors, which may cause the log file to be very large and even fill up the hard disk. At the same time, administrators will be faced with a large amount of logs painfully, and they may not even be able to discover the real intrusion route of the intruder.

Stuffing junk files into anonymous FTP. This can also fill up hard drive space.

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