packet catcher

happens Learn the network packet, write down to deepen your personal understanding, that's all. definition : The TCP/IP protocol defines a packet that is transmitted over the Internet (network layer), called a packet;IP packet (IP DataGram) composition : header, data part;header : divided into fixed part and variable p

Source: UDP Transport Packet SizeWhen it comes to UDP programming, the easiest question we can think about is how many bytes are sent at a time? Of course, this does not have the only answer, compared to the different systems, different requirements, the answer is not the same, I only like the ICQ type of sending chat messages for analysis, for other situations, you may also get a little help: First, we know, tcp/ IP is generally considered to be a fo

Landing ofData Packet AnalysisTools: Python-urllib2 | Firefox+firebug or Chrome, after using the browser to open the landing page, press F12 will open the developer tool by default or start Firebug, click on the network Monitoring packet, the following with a itune landing for an example.1. Enter itunes's login address in the browser: https://itunesconnect.apple.com/itc/static/login?view=1path=%2FWebObjects

UDP Packet Size Problem Post from: http://blog.csdn.net/buptzwp/archive/2009/12/22/5055487.aspx During UDP programming, the most common question is how many bytes are sent at a time? Of course, there is no unique answer. The answer is different from the requirements of different systems. Here we only analyze the situation of sending chat messages like ICQ, in other cases, you may be able to get some help:First, we know that TCP/IP is generally cons

As network security problems become increasingly serious, network security products have also been paid attention. As the first network security product and the most popular security product, firewall is also favored by users and R D institutions. From the perspective of firewall applications, there are basically two types: Network-level firewalls and personal firewalls. Windows is the most widely used PC operating system, so there are countless personal firewall products developed under Window

Http://www.oschina.net/p/pypcap ethereal comes with decoder of many protocols, which is simple and easy to use, an open-source software based on Winpcap. however, its architecture is not flexible. To add a custom decoder, you must modify the Code of Ethereal and re-compile it, very cumbersome. for general plain text protocols, there is no problem, but for encryption protocols, such as online games, the Program of the client sends a random key when the client is connected, and the subseq

Linux Network Application Programming Packet Tracer installation and interface introduction, packettracerIntroduction to Packet Tracer 1 Packet tracer is an auxiliary learning tool released by Cisco. It provides a network simulation environment for beginners of Cisco network courses to design, configure, and troubleshoot network faults. You can directly use the

Wireshark packet capture Analysis of TCP establishment and disconnection Process 1. Establish a connection over TCP Note: In this figure, Hosta acts as the client and hostb acts as the server. TCP is the transport layer protocol in the Internet. It uses the three-way handshake protocol to establish a connection. When the active Party sends a SYN connection request, wait for the other party to answer SYN, Ack. This method of establishing a connection

This article introduces some programming of the original socket (raw socket) implemented by C # in Windows Sockets and the network packet Monitoring Technology Based on this. Compared with winsock1, Winsock2 supports the raw socket type most obviously. Using raw socket, you can set the NIC to the hybrid mode. In this mode, we can receive the IP packet on the network, of course, for the purpose of not the lo

In fact, it has been a long time to explore the problem of network card packet capture. I found some basic things in the last few days. I will just repeat them here. Packet Capture first needs to know that the data transmitted through the NIC is actually through the underlying link layer (MAC). in Linux, the data traffic we obtain from the NIC is actually directly sent and received from the link layer. This

Problem DescriptionWhen you use a vro to access the Internet, the network speed is slow or unstable, and packet loss occurs on the ping Internet, as shown in the figure below:Ping packet loss is generally caused by physical connection quality or line congestion. We will analyze and troubleshoot the factors that are most likely to cause such problems. Please follow these steps to check:Troubleshooting1Reduce

H3C s5500 is the core and is linked to the s3100 of adjacent buildings. The user reports that the client network in 3100 is unstable. Link mode (5500) network cable (3100 MB photoelectric conversion) optical fiber to adjacent building (MB photoelectric conversion) network cable) First Ping, occasionally packet loss of 3%-5%, and occasionally good .. Strange Check whether the ports 3100 and 5500 are configured normally. Check whether the input and ou

(1) Obtain information such as the network interface name and mask (2) capture data packets (single data packet and multiple data packets) (3) Ethernet datagram capture (4) ARP packet capture (5) IP packet capture (6) TCP packet capture (7) UDP packet capture (8) ICMP

[TOC] Example of TCP sticky problem code in NettyNetty will occur in the TCP sticky packet and unpacking problems, of course, in fact, for the former network engineer, the first time to see this noun may be a bit uncomfortable, because in that we are talking about TCP cumulative send and Shard function, but the truth is the same.The code comes from the 4th chapter of the Netty authoritative guide, but I still make some changes to some of the cod

Packet Tracer Introductory One, Packet tracer introductionPacket Tracer is an assistive learning tool released by Cisco, which provides a network simulation environment for beginners in learning Cisco Web courses to design, configure, and troubleshoot network failures. The user can set up the network topology directly using the towing method in the software's graphical user interface, and can provide the de

Author: sodimethyl Source: http://blog.csdn.net/sodme statement: This article can be reproduced, reproduced, spread without the consent of the author, but any reference to this article please keep the author, source and this statement information. Thank you!The common network servers are basically 7x24. For online games, at least require the server to work continuously for more than a week and ensure that no catastrophic event such as server crash occurs. In fact, it is almost unrealistic to req

The 1th chapter, router-based packet filtering firewall General concepts of 1.1 packet filtering firewalls 1.1.1 What is a packet filter firewall A packet filtering firewall is a software that looks at the header of the packet that flows through it, thus determining the fate

For the TCP-based development of the communication program, there is a very important problem to be solved, that is, the package and unpacking. Let's talk about my thoughts on this question. If there is any wrong, the wrong place, begged everyone to correct. Thank you first. I. Why TCP-based communication programs require packets and unpacking. TCP is a "flow" protocol, the so-called flow, is a string of data without bounds. You can think of the river water, is connected into a piece, in the me

Document directory TCP packet TCP Reliability Assurance TCP data packets Source Port and destination port field -- each occupies 2 bytes. Identifies the application process of the sender and receiver. Number Field-4 bytes. Each byte in the data stream transmitted in the TCP connection is a serial number. The value of the serial number field refers to the sequence number of the first byte of the data sent in this section. The validation number

Programming | network Talking about socket programming, we may think of QQ and IE, yes. There are many network tools such as Peer-to-peer, NetMeeting and other applications implemented in the application layer, but also with the socket to achieve. The socket is a network programming interface that is implemented at the network application level, and Windows Sockets includes a set of system components that take advantage of Microsoft Windows message-driven features. The socket Specification versi