packet catcher

Solution to TCP packet sticking problem from http://hi.baidu.com/liuwenfei54/blog/item/24fe282dc1f7de34359bf7e1.html2007-03-07 Currently, TCP/IP communication protocol and its standard socket application programming interface (API) are widely used in network transmission applications ). The TCP/IP transport layer has two parallel protocols: TCP and UDP. TCP (Transport Control Protocol) is connection-oriented and provides high-reliability serv

Http://www.vckbase.com/index.php/wv/10http://blog.csdn.net/zlzlei/article/details/7689409Article One:Currently in the network transmission application, the TCP/IP communication protocol and its standard socket application Development Programming Interface (API) are widely adopted. The TCP/IP transport layer has two parallel protocols: TCP and UDP. TCP (Transport Control Protocol, transmission Protocol) is connection-oriented and provides high reliability services. UDP (User Datagram Protocol, Su

The process of sk_buff encapsulation and Network Packet encapsulation is described in detail.It can be said that the sk_buff struct is the core of the Linux network protocol stack, and almost all operations are performed around the sk_buff struct, its importance is similar to that of BSD's mbuf (I have read "TCP/IP details Volume 2"). What is sk_buff?Sk_buff is the network data packet itself and the operati

on the network. Therefore, the network analysis tools in the system are not a threat to the security of the local machine, but a threat to the security of other computers on the network. Tcpdump is defined as simple as possible, namely: dump the traffice on anetwork. a packet analysis tool that intercepts packets on the network according to the user's definition. As a necessary tool for the classic system administrator on the Internet, tcpdump, with

transmits data packets, if the length of the IP datagram plus the data frame header is greater than MTU, the data packets are divided into several parts for transmission and reorganized in the target system. For example, the maximum IP packet size (MTU) that can be transmitted over Ethernet is 1500 bytes. If the size of the data frame to be transmitted exceeds 1500 bytes, that is, the IP datagram length is greater than 1472 (1500-20-8 = 1472, normal

of the IP datagram plus the data frame header is greater than MTU, the data packets are divided into several parts for transmission and reorganized in the target system. For example, the maximum IP packet size (MTU) that can be transmitted over Ethernet is 1500 bytes. If the size of the data frame to be transmitted exceeds 1500 bytes, that is, the IP datagram length is greater than 1472 (1500-20-8 = 1472, normal datagram) bytes, the data frame needs

used to specify the maximum life cycle of each packet on the Internet. Each intermediate router reduces the TTL value by one before forwarding the IP packet to the next hop. A. Extract the final TTL value When a data packet arrives at the destination address to extract the TTL field value, this value is called the final TTL value. The challenge of hop count stat

I don't know how to say it. In short, the boat, from the mouth, I can not see HUANGFA and impoverished! I'm not going to say anything except cursing!Prior to BBR, there are two kinds of congestion control algorithms, based on packet loss and delay-based, regardless of which is based on detection, in other words, packet loss based on packet loss as a means to find

Packet Capture analysis tool-tcpdump Tcpdump (dump the traffic on a network) is a more practical tool for analyzing data packets in Unix, it supports filtering at the network layer, protocol, host, network or port, and provides logical statements such as and, or, not, and boolean expressions for packet header matching, in Linux, you can use yum to install yum if it is not installed. However, you need the fo

Compared with WINSOCK1, Winsock2 most obvious is to support the raw socket socket type, using raw socket, can set the network card into promiscuous mode, in this mode, we can receive IP packets on the network, of course, including the destination is not the local IP packet,Through the original socket, we can also more freely control the various protocols under Windows, and can control the network underlying transmission mechanism. In the example of th

In the last lecture, we learned how to get the appropriate information, this one will let us write a program Chiang every packet printed through the adapter.The function that opens the device is Pcap_open (). function prototypes arepcap_t* pcap_open (const char* source,int snaplen,int flags,int read_timeout,struct pcap_rmtauth *auth,char * errbuf); 'Pcap_rmatauth{int type.Char *username;;/ /zero-terminated string containing the username that have to i

There are three scenarios when a packet passes through a firewall:1. Local-Targeted packagesWhen a packet enters the firewall, if the destination address is native, the order in which the firewall is checked is as follows:If a packet is discarded at one step, no subsequent checks are performed Steps Table Chain Description

the rule, Determined by Target:A. Continue to match the next ruleB. Make some changes to the packetC. Jump to another chain (that is, start to match each rule on the chain from that chain sequentially)D. Return the chain that raised the jump (that is, the next rule that continues to match the chain before the jump)E. Dropping a packetF. Receiving packets (i.e. no further matching, direct return)G. LoggingH .... .The entire Iptables framework executes the following process:The loop 1:static brea

Linux Network firewall NetFilter: is a frame of the kernel: framework IPTABLES: Data packet filtering: Nat mangle and other rule generation tools Network knowledge: IP packet header NB Sp TCP headers NBSP;NBSP;NBSP;HDR Len Header First ministerial The bytes given must be multiplied by landscape 32/8 = 4 bytes typeof service (service type) service type total length (total length) Total messa

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

ScenarioIf you need to use UDP to transmit large data, such as 10 m images, this breaks through the design principles of UDP. UDP is designed based on "datax", that is, it assumes that each packet you send can be contained in a single package. In addition, the maximum length of UDP data packets is limited by the basic network protocol. The maximum theoretical length of UDP data packets is 65535 bytes, which contains 8 bytes of data headers and 65527

Tags: http OS AR for SP strong file data Div Pcap is a data packet capture library, which is used by many software as a data packet capture tool. Wireshark also uses the pcap library to capture data packets. The packets captured by pcap are not the original network byte streams, but are assembled to form a new data format. The file format of a data packet captur

Programming | Network talk 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 version

In the previous article (WEBRTC Audio-related Neteq (ii): Data structure) Neteq the main data structures, to understand the mechanism of Neteq lay a good foundation. This article is mainly about how the RTP packets received from the network in the MCU are put into packet buffer and taken out from packet buffer, as well as the calculation of the network delay value (optbuflevel) and the jitter buffer delay v

The use of the raw socket these days, with Python to write some demo program, recorded here. First, let's look at a simple sniffer program: Copy the Code code as follows: #! /usr/bin/python # code for Linux Import socket #s = Socket.socket (socket.af_inet, socket. SOCK_RAW, Socket. IPPROTO_UDP) s = socket.socket (socket.af_inet, socket. SOCK_RAW, Socket. IPPROTO_TCP) While True: Print S.recvfrom (65535) The data is received directly from the raw socket and the print operation is direct. This