packet catcher

Analysis of Layer 2 (Link Layer) packet sending ProcessAnalysis of L2 (Link Layer) packet sending process -- lvyilong316 Note: The kernel version involved in this series of blog posts is 2.6.32.After a packet is prepared on the upper layer, the packet is sent to the link layer. The dev_queue_xmit function processes the

IOS development-use Charles for https packet capture In the previous two blogs, "introduction and use of the network packet capture tool Charles" and "iOS development-detailed explanation of http packet capture using Charles" gave a detailed explanation of Charles's http packet capture. Today, we will implement https

The serial number (sequence number) in a TCP packet is not numbered by the packet segment. Instead, all the data transmitted during the connection life cycle is treated as a byte stream, the serial number is the number of each byte in the entire byte stream. A tcp data packet contains data of multiple byte streams (that is, data segments), and the data size of ea

Ps:tcpdump is a tool for intercepting network groupings and outputting grouped content, which is simply the packet capture tool. With its powerful capabilities and flexible interception strategy, tcpdump is the preferred tool for network analysis and troubleshooting in Linux systems.Tcpdump provides source code, exposes interfaces, and is therefore highly extensible, and is a useful tool for network maintenance and intruders. Tcpdump exists in the bas

[Keywords] TCP/IP packet structure explanation network protocol In general, we only need to call some encapsulated functions or components for network programming to complete most of the work. However, 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 fo

Actually, for the tcpdump program, you can even say that this program is actually a customer experience, because not only can he analyze the packet flow direction, but the internal content of the packet can also be "audible". If the information you use is clear, on the router, it may have been heard by others! Awesome! So, let's get to know this experience! (Authorization: This tcpdump must use the root ide

provides a Transport Driver Interface (TDI) to the top, and interacts with the upper border of the NDIS middle layer through the NDIS interface, the bottom boundary of the NDIS intermediate layer interacts with the underlying NDIS miniport driver through the NDIS interface. Finally, the NDIS miniport driver uses the NDIS interface to interact with the netcard of the physical network device. Introduction to NDIS Interfaces The original communication can be viewed as follows: After the pr

Introduction The author was fortunate to participate in the overall project design of the third generation mobile communication technology test network of the Ministry of Information Industry and the design work of the Beijing Area Test Network project. 3G test Network adopts WCDMA R99, CDMA2000 1X, TD-SCDMA three kinds of technology construction. When considering the 3g scheme, we combine the characteristics of 3G network, based on satisfying the requirements of the test, and draw on the exper

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 must indicate the author, source and the statement information of the bank. Thank you! The packet analysis method is simple and simple, that is: comparison! We need to constantly compare and analyze packets from different perspectives, and make full use of your imagin

R1 --------------- (vlan10) SW (vlan20) ------------------ R2Condition: R1: 192.168.1.1 mac: a R2: 192.168.1.2 mac: BSw is a layer-3 SwitchWhen R1 packets are forwarded to R2:When R1 receives the data packet, it queries the route table of R1. The purpose of querying the route table is to find the data packet from that interface. After finding the interface, what type of frames are encapsulated for the purpo

such as the Cisco 2960x-24ps-l (24,000 Gigabit Port 4,000 gigabit), forwarding bandwidth 108Gbps, switching bandwidth 216Gbps, packet forwarding rate 71.4Mpps, according to the non-clogging line speed forwarding to calculate, exchange capacity of 2*28*1gbps=56gbps, The nominal 216Gbps is much higher than this, why? Is it due to the different design of the switch matrix? How did he figure out the 216Gbps? Again, for example: its

Label: style blog HTTP Io ar OS use SP strong Wireshark introduction: Wireshark is one of the most popular and powerful open-source packet capture and analysis tools. Popular in the sectools security community, once surpassed metasploit, Nessus, aircrack-ng and other powerful tools. This software plays a major role in network security and forensic analysis. As a network data sniffing and protocol analyzer, it has become a required tool for network

Recently, RTP has naturally involved the jrtplib library, reading code 3.7.1, spare time, and some excerpt. I hope you can remember it quickly in the future. I also hope your friends can read it and point out improper information, we provide you with valuable suggestions to learn and make progress together.Next, the source code analysis notes are based on: # ifndef rtp_support_thread. The author uses related classes for background threads to process the receipt of RTP packets, however, we will a

[Scenario description] The client is started, and the server is started. The client initiates a connection The client sends a packet containing the four bytes of "Hutu" Client disconnection, server disconnection [Process diagram]No picture, no truth! [Socket status change diagram]No picture, no truth! Establish a connection protocol (three-way handshake) (1) the client sends a TCP packet with SYN

Recently, there have been frequent disconnection of hosts on the network. It was normal at the beginning, but the disconnection may occur after a period of time, sometimes very fast recovery, but sometimes it may take several minutes, this has a huge impact on the work. Initially, I suspected whether it was a physical error. In short, I started to check the most easy-to-start items. No exceptions were found after the check! I suddenly think of the most popular ARP attacks on the Internet, and th

Packet forwarding rate is an important indicator that affects route performance. Here we mainly explain the specific application of packet forwarding rate in routing. There are many indicators when describing the performance of a vswitch, such as switching capacity (Gbps), Board bandwidth (Gbps), throughput or packet forwarding rate (Mpps) and so on. The most imp

ICMP Packet AnalysisI. Overview:1. ICMP allows the host or route to report errors and provide relevant exceptions. ICMP is a standard protocol for the Internet, but ICMP is not a high-level protocol, but an IP layer protocol. Generally, ICMP packets are used by the IP layer or higher-level protocols (TCP or UDP. Some ICMP messages return error messages to the user process.2. The ICMP packet is used as the d

TCP/IP packet structure In general, we only need to call encapsulated functions or components to complete most of network programming. However, in some special cases, we need to have a deep understanding of the structure of network data packets, 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. There are more than 10 pro

1. tcpdump is a good tool for tracking the system behavior of processes in the local machine. in the debugging of network problems, tcpdump is an indispensable tool, like most excellent linux tools, it features simplicity and power. By default, tcpdump does not capture packets for internal communication on the local machine. According to the network Association I,Tcpdump Strace is a good tool for tracking system behavior calls of processes in the local machine. in network debugging, tcpdump is a

In order to prevent crawlers from crawling articles on unscrupulous websites, we hereby mark and repost the source of the article. Laplacedemon/sjq. Http://www.cnblogs.com/shijiaqi1066/p/3898248.html Overview The tcpdump command is a Linux packet capture command tool that is powerful and easy to use. Tcpdump is developed based on the underlying libpcap library and requires the root permission to run the program. Basic usage and Command Options For e