tcp udp port scan

, indicate the address and port number of the server-side socket, and then make a connection request to the server-side socket. Connection confirmation: When a server-side socket hears or receives a connection request from a client socket, it responds to a client socket request, establishes a new thread, sends a description of the server-side socket to the client, and once the client confirms the description, the two sides formally establish the conne

In the socket network program, TCP and UDP are both connection-oriented and non-connection-oriented. So TCP's socket programming, send and receive both sides (client and server side) must have one by one pairs of sockets, so the sender in order to send a number of packets to the receiver, more effective to the other side, using the optimization method (Nagle algorithm), will be a small number of intervals a

1. Brief Introduction to UDP UDP is a transport layer protocol, which is in a layer with TCP protocol. However, unlike TCP, UDP does not provide timeout retransmission, error retransmission, and other functions, that is, it is an unreliable protocol.2.

UDP belongs to the transport layer together with the TCP mentioned earlier. UDP differs from TCP in that it is a non-connection-oriented protocol, that is, when both parties communicate with each other, they do not need to establish a connection beforehand. So the UDP heade

SOCKET, TCP/UDP, HTTP, FTP (a) tcp/udp,socket,http,ftp brief analysis TCP/IP is a protocol group that can be divided into three levels: the network layer, the transport layer, and the application layer:Network layer: IP protocol, ICMP protocol, ARP protocol, RAR

following is a detailed introduction to several concepts and principles in network communication:(1) socket (socket):Socket (socket) is the cornerstone of communication and is the basic operating unit of network communication supporting TCP/IP protocol. It is an abstract representation of the endpoint in the network communication process and contains five kinds of information that must be used for network communication: the protocol that the connecti

sockets, TCP/UDP, HTTP, FTP(a) A brief analysis of TCP/UDP,SOCKET,HTTP,FTP TCP/IP is a protocol group that can be divided into three tiers: the network layer, the transport layer, and the application layer:Network layer: IP protocol, ICMP protocol, ARP protocol

server can directly respond to the syn+ack at the same time, when the shutdown request is received, because it is not sure that the data has been sent, so the first response to the client, and then determine whether the data is sent, and then confirm that it can be closed to the client, it is four times waved; The Baotou structure of TCP Source Port 16-bit destination

1.UDP Brief Introduction UDP is a transport layer protocol, and TCP protocol is in a hierarchy, but unlike the TCP protocol, UDP protocol does not provide timeout retransmission, error retransmission and other functions, that is, it is unreliable protocol. 2.

TCP HTTP UDP:is the communication protocol, that is, the rules of communication, only the two parties in accordance with this rule "speak", the other party can understand or serve.TCP/IP stands for Transmission Control Protocol/Internet Protocol, which refers to a series of protocols. TCP和UDP使用IP协议从一个网络传送数据包到另一个网络。把IP想像成一种高速公路，它允许其它协议在上面行驶并找到到其它电脑的出口。

I. Overview TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are two different communication protocols at the transport layer in the network architecture TCP/IP model. TCP: Transmission Control Protocol, a connection-oriented protocol that provides a reliable full-duplex byte stream for user proce

data to be received. If no data is received, it enters the waiting state. The program stops at the receive () function. if it receives data, the program will continue to run. Therefore, the next action can be determined based on the read datagram, which achieves the same effect as the network listener. If UDP is not connected, send () and receive () are sent. TCP needs to obtain an outputstream and input

control bits of the header to confirm the data. Confirm that the destination is emitted, and use it to tell the sender that the data segment before the serial numberAll received. For example, the confirmation number is x, that is, the first X-1 data segment received, only when ack=1, the confirmation number is valid, when ack=0, the confirmation number is invalid, this will require retransmission of data, to ensure the integrity of the data.SynSynchronize serial number,

(a) A brief analysis of Tcp/udp,socket,http,ftp TCP/IP is a protocol group that can be divided into three levels: the network layer, the transport layer, and the application layer:Network layer: IP protocol, ICMP protocol, ARP protocol, RARP protocol, and BOOTP protocolTransport layer: TCP protocol and

First, the DNS domain Name System(1) DNS domain Name System: A distributed database in which domain names and IP addresses are mapped to each other.(2) The DNS protocol runs on top of the UDP protocol , using a port number of 53.(3) Each IP address can have a host name, static mapping and dynamic mapping.Ii. advantages and disadvantages of TCP and

Photon Server engine (ii) Implementation of SOCKET/TCP/UDP Foundation and unity chat roomWhat do we usually say the most socket is, in fact, the socket is the TCP/IP protocol encapsulation, the socket itself is not a protocol, but a call interface (API).With the socket, we can use the TCP/IP protocol. In fact, the sock

socket.To do this, the client's socket must first describe the socket that describes the server to which it is connected, indicating the address and port number of the server end socket. The connection request is then made to the server-side socket.Connection acknowledgement: When the server-side socket hears or receives a connection request to the client socket. In response to a client socket request. Set up a new thread to send the description of t

as follows: Keep the source address of the packet sent from host UDP port, however, only the packets sent from the destination IP address/port of the previously sent packet to port a of the host can pass the firewall. Currently, the low-end routes are all full cone.Nat is also the best support for P2P network drilling

**TCP and UDP Difference Summary:1, TCP connection-oriented (such as phone calls to establish a connection before the dial); UDP is connectionless, that is, no connection needs to be established before data is sent2, TCP provides a reliable service. In other words, the data

running result is as follows: 2. UDP-based network applications The preceding describes TCP-based network applications. For convenience of comparison, the following describes the design of UDP-based network applications. As above, we should first accept the development steps of UDP-based network applications: Server