packet sniffer

In general, for network programming, we only need to call encapsulated functions or components to complete most of the work, but in some special cases, we need to have a deep understanding. Network Packet structure and protocol analysis. Such as network monitoring and troubleshooting ...... The IP package is insecure, but it is the foundation of the Internet and widely used in various aspects. More than 10 protocol families (as far as I know) derived

outputs a slightly detailed information. For example, the IP package can contain TTL and service type information;-VV: Output detailed message information;-C. After receiving the specified number of packages, tcpdump stops;-F Read the expression from the specified file and ignore other expressions;-I indicates the network interface of the listener;-R reads packets from a specified file (these packets are generally generated using the-W option );-W directly writes the package into the file and d

ptcl ;????????? // Protocol typeUshort Plen ;??????? // Length of TCP/UDP packets (that is, the length unit from the calculation of the TCP/UDP header to the end of the packet: bytes)} Psd_header;?? This process is a very tedious process. After several computations, I can no longer endure such repetitive work. So I wrote a general computing function. I feel very convenient to use this function: encapsulate your data

Wireshark data packet capture tutorialWireshark data packet capture tutorial understanding capture analysis data packet understanding Wireshark capture data packet when we understand the role of the main Wireshark window, learn to capture data, then we should understand these captured data packets. Wireshark displays t

outputs a slightly detailed information. For example, the IP package can contain TTL and service type information;-VV: Output detailed message information;-C. After receiving the specified number of packages, tcpdump stops;-F Read the expression from the specified file and ignore other expressions;-I indicates the network interface of the listener;-R reads packets from a specified file (these packets are generally generated using the-W option );-W directly writes the package into the file and d

The preceding section analyzes the initialization process of the ARP protocol. This section is primarily an ARP packet processing process that, when ARP is initialized, adds the receive handler function of the ARP protocol to the hash list associated with the three-layer protocol packet processing function by calling Dev_add_pack Ptype_ In base (for a hash list related to the three-layer protocol

The common ICMP packet Echo is the consulting information. The ping command uses this type of ICMP packet. When the ping command is used, an ICMP packet of the Echo-query type will be sent to the target host, and after the target host receives the ICMP packet, the Echo-response type ICMP

Layer-3 Ethernet switches are quite common, so I have studied the problems related to the CPU packet sending and receiving of layer-3 Ethernet switches. I would like to share them with you here, hoping they will be useful to you. Layer-3 Ethernet switches are developing rapidly. On the one hand, bandwidth and switching capacity of network devices are greatly increased, and the types of protocols supported by devices are also increasing with the increa

Implement router and packet filtering firewall in Linux Router and Firewall]Vro is a widely used device between IP segments. There are many ready-made products on the market. In applications, we often connect routers across the WAN and lan. Most router products are designed based on this need. However, with the expansion of the user's IP network, we need a router that can address multiple Ethernet networks. The traditional router products occasionall

Network Packet monitoring using raw socket programming in C # Author: Unknown When talking about socket programming, you may think of QQ and IE. That's right. Many other network tools, such as P2P and Netmeeting, are implemented at the application layer using socket. Socket is a network programming interface that is implemented on the network application layer. Windows Socket includes a set of system components that fully utilize the features of Micro

Use libpcap for packet capture and package settlement on Ubuntu 14.04 64-bit For development purposes, I decided to use the latest libpcap source code package for installation. To install the libpcap library in a Unix environment, you mustC compiler, flex, bison, etc. These packages are not available when Ubuntu is installed. To install flex, the m4 compiling environment is required. Otherwise, the error "GNU M4 is required" is prompted. 1. Install th

Analysis of data packet sending process in two-layer (link layer) Analysis of data packet sending process in two-layer (link layer)--lvyilong316 Description: The kernel version covered in this series of posts is 2.6.32When the upper layer is ready for a package, the link layer packet is sent to the link layer, which is handled primarily by the Dev_queue_xmit fun

When talking about socket programming, you may think of QQ and IE. That's right. Many other network tools such as P2P and Netmeeting are implemented at the application layer. Program Is also implemented using socket. Socket is a network programming interface that is implemented on the network application layer. Windows Socket includes a set of system components that fully utilize the features of Microsoft Windows message driver. The socket Specification Version 1.1 was released in January 1993

Transferred from Author's blog:Http://blog.csdn.net/cilong521/ When talking about socket programming, you may think of QQ and IE. That's right. Many other network tools, such as P2P and Netmeeting, are implemented at the application layer using socket. Socket is a network programming interface that is implemented on the network application layer. Windows Socket includes a set of system components that fully utilize the features of Microsoft Windows message driver. The socket Specification Versi

Introduction to three exchange technologies1. Circuit Switching TechnologyThe network switching technology has gone through four stages: Circuit Switching Technology, packet switching technology, group switching technology and ATM technology. Public Telephone Network (PSTN) and mobile network (includingBoth GSM and CDMA networks use circuit switching technology. The basic feature of this technology is connection-oriented.For a fixed-bandwidth communic

Yesterday, a brother who studied network programming was vague about some protocols and concepts in TCP/IP. He wanted me to explain ICMP to him. This is not empty, so I grabbed an ICMP packet and analyzed it for him:(The previous conceptual things are basic and mandatory !) An ICMP packet is contained in an IP address datagram. The IP address header is in front of the ICMP

How should I avoid packet loss when a large amount of data is continuously transmitted over TCP? For example, sending a file. I remember someone mentioned the possible stack overflow. How can this problem be avoided? Can I send a confirmation packet after receiving the data? After receiving the confirmation packet, I will continue to send it. Or sleep after

The TCP protocol specifies a server port number for the HTTP process , typically a request by an HTTP client to establish a TCP connection to the server-specified port (by default, port 80). (Note that this refers to port 80 for server development) The HTTP server listens on that port for requests sent by the client.Open the Wireshark grab packet, filter the HTTP protocol, File–export objects–http Select the package that needs to be exported, and then

C # Raw Socket for network packet monitoring, 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 local IP packet, through the original socket, we can also more freely control the vari

Wireshark Introduction Wireshark official download site: http://www.wireshark.org/ Wireshark is a very popular network packet analysis software with powerful functions. You can intercept various network packets to display the details of network packets. Wireshark is an open-source software that can be safely used. It can run on Windows and Mac OS. Wireshark users must understand the network protocol. Otherwise, they cannot understand Wireshark. Wires