Conclusion: 1. Internet 548bytes. 2. Lan 1472 bytes
Lan
The link layer MTU (maximum transmission unit) is 1500 bytes. MTU refers to the maximum transmitted data, excluding the link layer header and tail.
Therefore, IP header (20 bytes) + IP packet data = 1500 bytes, and IP packet data = 1480 bytes
The first 8 bytes of UDP, so the UDP data is 1472 bytes.
Internet
MTU: 576, available above
Protoc
TCP, UDP programming exercisesTCP☆ Upload text fileReads a local text file, sends the data to the server side, and stores the data. After the storage is complete, give the client a hint.first, the idea of solving problemsClient: (1) Create socket object----with server ip+ port number(2) read the contents of the file(3) through the socket to send the content to the server side (the socket in the output stream packaging "print stream" for sending text,
) filtercontext {NSLog (@ "receivedata =%@, fromaddress =%@", [[NSString alloc] Initwithdata:data encoding:nsutf8stringencoding],[[ NSString Alloc] initwithdata:address encoding:nsutf8stringencoding]);NSString *host = nil;uint16_t port = 0;[Gcdasyncudpsocket gethost:host port:port fromaddress:address];//The IP and port from which the service-side response can be obtained for subsequent TCP connectionsNSLog (@ "Adress =%@%i", host,port);}A mobile phone set up
UDP Machine Control ProjectProtocol Message Format:Ver + T + TKL + Code + MessageID + 11111111 + Command + Payload /c1>01 + (00 | 01 | 02 | 03) + (000000)The E0 4C 1E 5C 4C//dev->ser Device Login Request: message number: 0, ID is xx E0 4C1E,5C The FF E0 4C 1E 5C 4C//ser->dev Server login response: message number: 0, the ID is xx E0 4C1E 5C 4C
E0 4C 1E 5C 4C//Dev->ser device Logout Request: message number: 1, id is xx E0 4C1E 5C 4C The FF E0
I. Summary
This blog post focuses on"Design and Implementation of UDP-based network cameras "describes problems encountered during debugging and describes the solution process.
Ii. Experimental Platform
Hardware Platform: diy_de2
Software Platform: Quartus II 9.0 + NiO II 9.0 + Visual Studio 2008
Iii. experiment content
The VGA display is used as a reference for comprehensive debugging to make the C # Video Display normal. The displa
Python network programming-UDP implementation, python network programming udpI. Introduction:
Python udp is connectionless, without three-way handshake of TCP, error retransmission mechanism, sending only sending, receiving only receiving, the efficiency is higher than TCP, used in places where the data frame is not high, for example, video and audio transmission
II. Implementation Process:
The server proce
Android uses UDP to transmit data, which causes Chinese garbled characters. Android udp
Recently, the company needs to develop towards the smart home industry. We need to use UDP to transmit data and find some information on the Internet. However, we found garbled Characters During Chinese transmission, the problem is finally solved. The following is the key code
Linux Network Programming 5-use UDP protocol for group chat and network programming udpIntroduction
The functions implemented in this article are similar to what I wrote earlier (select System Call _ 2 in Linux). The difference is that the communication methods between processes are different. In the previous article, I used pipelines. In this article, I will use the socket interface.Requirement
The client sends a message to the server. After receivin
Send UDP broadcast and receive data in ios development, and develop udp broadcast in iosWith asyncUdpSocket, the server responds after receiving the broadcast, and then starts communication.
-(Void) init {
AsyncUdpSocket * socket = [[AsyncUdpSocketalloc] initWithDelegate: self];
[SocketlocalPort: 16747];
NSTimeInterval timeout = 5000;
NSString * request = @ "quick_stat ";
NSData * data = [NSDatadataWithData
create (and maintain) a connection when passing data. This connection adds overhead to the communication process, making it slower than UDP. Resource Consumption of TCP connections, including packet information, condition status, and serial number.
TCP connection has security risks: by deliberately failing to complete the three-way handshake process required for establishing a connection, the resources of the connection party are exhausted.
The pre
connection in the buffer. At this point, if the legitimate user 61.61.61.61 again to send legitimate data, the server has no such connection, the user must start to establish a new connection. Attack, the attacker will forge a large number of IP address, to send the RST data to the target, so that the server does not serve legitimate users, thereby achieving the victim server denial of service attacks.
3. UDP flo
connection consumes the system's CPU, memory, and other hardware resources. Moreover, because TCP has the confirmation mechanism, three times handshake mechanism, these also can cause the TCP to be exploited, realizes the DOS, the DDoS and so on attacks.TCP Application Scenario: when the network communication quality requirements , such as: the entire data to be accurate to each other, such as the browser (HTTP).(2) UDPThe advantages of UDP: fast , s
resources.Moreover, because TCP has the confirmation mechanism, three times handshake mechanism, these also causes TCP to be easy to use, realizes DOS, DDOS, CC and so on attack. the advantages of UDP:
Faster, a little more secure than TCP.UDP has no TCP handshake, acknowledgement, window, retransmission, congestion control mechanism, UDP is a stateless transport protocol, so it is very fast when passing d
communication must first establish a connection, then data transmission, and finally remove the connection three processes. tcp when you make a connection, it's three steps away: The first step Syn that is, the tcp synchronize message, syn sync message indicates the port used by the client and tcp The second step , the server receives the client's syn After the message, a syn+ack tcp ack acknowledgement The third step ack to the server side, the same tcp The serial number is
malicious attack.
Most firewalls now know SYN/FIN packets, and some other combinations, such as SYN/FIN/PSH, SYN/FIN/RST, SYN/FIN/RST/PSH. Obviously, when such a package appears on the network
Your network must have been attacked.
Other known illegal packages include FIN (no ACK mark) and NULL. As discussed earlier, because ACK/FIN packets are generated to close a TCP connection, normal FIN packets always contain ACK
Mark. A "NULL" packet is a packet without any TCP flag (URG, ACK, PSH, RST
ARP part
IP ICMP
UDP part
TCP Section
1. UDP IntroductionUDP is a simple datagram-oriented transport layer protocol. Each output operation of a process generates a UDP datagram and assembles it into an IP datagram to be sent. This is different from the stream-oriented character protocol, such as TCP. The full data generated by the application may be unrelated to
UDP packet LengthThe theoretical length of UDP packetsWhat is the theoretical length of UDP packets and what should be the appropriate UDP packets? As can be seen from the packet header of the UDP packet in the 11th chapter of TCP-IP, the maximum packet length of
In network programming, UDP is used as the data transmission protocol for scenarios with high real-time data transmission requirements, in the TCP/IP protocol family, UDP protocol requires less network system resources than TCP protocol. However, in enterprise applications, due to network security reasons, IP data other than specific ports cannot pass through dedicated routes or gateways. To support such ap
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