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SYN Flood
A SYN flood is a form of denial-of-service attack on data communications in which an attacker rapidly initiates a connection to a server without finalizing the connection. The server has to spend resources waiting for half-opened connections, which can consume enough resources to make the system unresponsive to legitimate traffic. The packet that the attacker sends is the SYN packet, a part of TCP's three-way handshake used to establish a connection. Technical details When a client attempts to start a TCP connection to a server, the client and server exchange a series of messages which normally runs like this: #The client requests a connection by sending a SYN (''synchronize'') message to the server. #The server ''acknowledges'' this request by sending SYN-ACK back to the client. #The client responds with an ACK, and the connection is established. This is called the TCP three-way handshake, and is the foundation for every connection established using the TCP protocol. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tcp Normal
TCP may refer to: Science and technology * Transformer coupled plasma * Tool Center Point, see Robot end effector *Topologically close pack (TCP) phases, also known as Frank-Kasper phases Computing * Transmission Control Protocol, a fundamental Internet standard * Telephony control protocol, a Bluetooth communication standard * FAST TCP, a TCP congestion avoidance algorithm * TCP/IP, the Internet protocol suite Medicine * TCP (antiseptic) * Tenocyclidine, an anesthetic drug * Toxin-coregulated pilus, a protein that allows ''Vibrio cholerae'' to adhere to enterocytes * Transcutaneous pacing Chemistry * 1,2,3-Trichloropropane, an industrial solvent * Thermal conversion process, a depolymerization process for producing crude oil from waste * Tocopherols, a class of methylated phenols * Tricalcium phosphate, an anticaking agent * Trichlorophenol, any organochloride of phenol that contains three covalently bonded chlorine atoms * Tricresyl phosphate, an organophosphate compound ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IP Address
An Internet Protocol address (IP address) is a numerical label such as that is assigned to a device connected to a computer network that uses the Internet Protocol for communication. IP addresses serve two main functions: network interface identification, and location addressing. Internet Protocol version 4 (IPv4) was the first standalone specification for the IP address, and has been in use since 1983. IPv4 addresses are defined as a 32-bit number, which became too small to provide enough addresses as the internet grew, leading to IPv4 address exhaustion over the 2010s. Its designated successor, IPv6, uses 128 bits for the IP address, giving it a larger address space. Although IPv6 deployment has been ongoing since the mid-2000s, both IPv4 and IPv6 are still used side-by-side . IP addresses are usually displayed in a human-readable notation, but systems may use them in various different computer number formats. CIDR notation can also be used to designate how much ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UDP Flood Attack
A UDP flood attack is a volumetric denial-of-service (DoS) attack using the User Datagram Protocol (UDP), a sessionless/connectionless computer networking protocol. Using UDP for denial-of-service attacks is not as straightforward as with the Transmission Control Protocol (TCP). However, a UDP flood attack can be initiated by sending a large number of UDP packets to random ports on a remote host. As a result, the distant host will: * Check for the application listening at that port; * See that no application listens at that port; * Reply with an ICMP Destination Unreachable packet. Thus, for a large number of UDP packets, the victimized system will be forced into sending many ICMP packets, eventually leading it to be unreachable by other clients. The attacker(s) may also spoof the IP address of the UDP packets, ensuring that the excessive ICMP return packets do not reach them, and anonymizing their network location(s). Most operating systems mitigate this part of the attac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smurf Attack
A Smurf attack is a distributed denial-of-service attack in which large numbers of Internet Control Message Protocol (ICMP) packets with the intended victim's spoofed source IP are broadcast to a computer network using an IP broadcast address. Most devices on a network will, by default, respond to this by sending a reply to the source IP address. If the number of machines on the network that receive and respond to these packets is very large, the victim's computer will be flooded with traffic. This can slow down the victim's computer to the point where it becomes impossible to work on. History The original tool for creating a Smurf attack was written by Dan Moschuk (alias TFreak) in 1997. In the late 1990s, many IP networks would participate in Smurf attacks if prompted (that is, they would respond to ICMP requests sent to broadcast addresses). The name comes from the idea of very small, but numerous attackers overwhelming a much larger opponent (see Smurfs). Today, administra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ping Flood
A ping flood is a simple denial-of-service attack where the attacker overwhelms the victim with ICMP "echo request" ( ping) packets. This is most effective by using the flood option of ping which sends ICMP packets as fast as possible without waiting for replies. Most implementations of ping require the user to be privileged in order to specify the flood option. It is most successful if the attacker has more bandwidth than the victim (for instance an attacker with a DSL line and the victim on a dial-up modem). The attacker hopes that the victim will respond with ICMP " echo reply" packets, thus consuming both outgoing bandwidth as well as incoming bandwidth. If the target system is slow enough, it is possible to consume enough of its CPU cycles for a user to notice a significant slowdown. A ping flood can also be used as a diagnostic for network packet loss and throughput issues. See also * INVITE of Death *Ping of death *Smurf attack A Smurf attack is a distributed denial- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internet Control Message Protocol
The Internet Control Message Protocol (ICMP) is a supporting protocol in the Internet protocol suite. It is used by network devices, including routers, to send error messages and operational information indicating success or failure when communicating with another IP address. For example, an error is indicated when a requested service is not available or that a host or router could not be reached. ICMP differs from transport protocols such as TCP and UDP in that it is not typically used to exchange data between systems, nor is it regularly employed by end-user network applications (with the exception of some diagnostic tools like ping and traceroute). A separate Internet Control Message Protocol (called ICMPv6) is used with IPv6. Technical details ICMP is part of the Internet protocol suite as defined in RFC 792. ICMP messages are typically used for diagnostic or control purposes or generated in response to errors in IP operations (as specified in RFC 1122). ICMP ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fraggle Attack
A Smurf attack is a distributed denial-of-service attack in which large numbers of Internet Control Message Protocol (ICMP) packets with the intended victim's spoofed source IP are broadcast to a computer network using an IP broadcast address. Most devices on a network will, by default, respond to this by sending a reply to the source IP address. If the number of machines on the network that receive and respond to these packets is very large, the victim's computer will be flooded with traffic. This can slow down the victim's computer to the point where it becomes impossible to work on. History The original tool for creating a Smurf attack was written by Dan Moschuk (alias TFreak) in 1997. In the late 1990s, many IP networks would participate in Smurf attacks if prompted (that is, they would respond to ICMP requests sent to broadcast addresses). The name comes from the idea of very small, but numerous attackers overwhelming a much larger opponent (see Smurfs). Today, administra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SYN Cookies
SYN cookie is a technique used to resist SYN flood attacks. The technique's primary inventor Daniel J. Bernstein defines SYN cookies as "particular choices of initial TCP sequence numbers by TCP servers." In particular, the use of SYN cookies allows a server to avoid dropping connections when the SYN queue fills up. Instead of storing additional connections, a SYN queue entry is encoded into the sequence number sent in the SYN+ACK response. If the server then receives a subsequent ACK response from the client with the incremented sequence number, the server is able to reconstruct the SYN queue entry using information encoded in the TCP sequence number and proceed as usual with the connection. Implementation To initiate a TCP connection, the client sends a TCP SYN packet to the server. The server responds with a TCP SYN+ACK packet, which includes a sequence number used by TCP to reassemble the data stream. According to the TCP specification, the initial sequence number sent by an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TCP Half-open
The term half-open refers to TCP connections whose state is out of synchronization between the two communicating hosts, possibly due to a crash of one side. A connection which is in the process of being established is also known as embryonic connection. The lack of synchronization could be due to malicious intent. RFC 793 According tRFC 793 a TCP connection is referred to as ''half-open'' when the host at one end of that TCP connection has crashed, or has otherwise removed the socket without notifying the other end. If the remaining end is idle, the connection may remain in the half-open state for unbounded periods of time. Stateful Firewall Timeout Another circumstance that can lead to half-open connections is if a stateful firewall times out a connection that is idle for too long. In this case, the firewall clears its internal state, and if either side of the connection sends a packet, the firewall will drop the packet. This will often result in a half-open connection a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IP Address Spoofing
In computer networking, IP address spoofing or IP spoofing is the creation of Internet Protocol (IP) packets with a false source IP address, for the purpose of impersonating another computing system. Background The basic protocol for sending data over the Internet network and many other computer networks is the Internet Protocol (IP). The protocol specifies that each IP packet must have a header which contains (among other things) the IP address of the sender of the packet. The source IP address is normally the address that the packet was sent from, but the sender's address in the header can be altered, so that to the recipient it appears that the packet came from another source. The protocol requires the receiving computer to send back a response to the source IP address therefore spoofing is mainly used when the sender can anticipate the network response or does not care about the response. The source IP address provides only limited information about the sender. It may pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tcp Synflood
TCP may refer to: Science and technology * Transformer coupled plasma * Tool Center Point, see Robot end effector *Topologically close pack (TCP) phases, also known as Frank-Kasper phases Computing * Transmission Control Protocol, a fundamental Internet standard * Telephony control protocol, a Bluetooth communication standard * FAST TCP, a TCP congestion avoidance algorithm * TCP/IP, the Internet protocol suite Medicine * TCP (antiseptic) * Tenocyclidine, an anesthetic drug * Toxin-coregulated pilus, a protein that allows ''Vibrio cholerae'' to adhere to enterocytes * Transcutaneous pacing Chemistry * 1,2,3-Trichloropropane, an industrial solvent * Thermal conversion process, a depolymerization process for producing crude oil from waste * Tocopherols, a class of methylated phenols * Tricalcium phosphate, an anticaking agent * Trichlorophenol, any organochloride of phenol that contains three covalently bonded chlorine atoms * Tricresyl phosphate, an organophosphate compound ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
