linux packet sniffer

The packet processing process in Linux kernel bridge-general Linux technology-Linux programming and kernel information. The following is a detailed description. 1. Preface This article briefly introduces the process of handling data packets on the Linux network protocol sta

Cause Analysis of UDP packet loss in linux kernel 1. UDP checksum and error phenomenon: you can use netstat-su to view UDP error packets. Tcpdump packet capture: enable the captured udp packet in wireshark and enable the checksum option. Solution: Find Link faults www.2cto. com2, firewall... cause analysis of UDP

Recently, my company thought it was a network problem or a data center problem when a packet loss problem occurred on its website. after a long time of troubleshooting, I found that the linux network card was out of the package. Let's share my solution. In the past, the company's system often experienced packet loss due to network card problems (

transmission of the eth0 NIC to randomly discard 1% of packets.You can also set the success rate of packet loss:# TC Qdisc Add dev eth0 root netem loss 1% 30%This command sets the transmission of the eth0 NIC to randomly discard 1% of packets, with a success rate of 30%.3 , simulated packet duplication# TC Qdisc Add dev eth0 root netem duplicate 1%This command sets the transmission of the eth0 NIC to rando

Packet capture analysis is usually required when debugging network programs in Linux. Tcpdump in Linux is good. By default, Ubuntu has been installed. The following is a practical example. for example, I have a C ++ program listening to the local port 8889, and another newlisp program communicating with it through TCP. First, you can check...

Release date:Updated on: Affected Systems:Linux kernel Description:--------------------------------------------------------------------------------Bugtraq id: 64744CVE (CAN) ID: CVE-2013-7270 Linux Kernel is the Kernel of the Linux operating system. In versions earlier than Linux kernel 3.12.4, the function packet_recvmsg in net/

Production of a Linux device concurrency is relatively large, droped packet more, especially in the running game packets, there is a serious loss of packet phenomenon, suspected network card performance, in the replacement of equipment before the solution through the software method, through some data on the internet to show that this phenomenon, Also may be the

Use of Packet Socket in Linux Hanse 2009-4-3 Linux supports PF_PACKET Sockets for user-layer network protocols. With this SOCK_RAW Packet socket, the application can directly receive a data frame with a complete Layer 2 data frame, and then use this socket to send a Layer 2 data frame. Therefore, the underlying network

PF_PACKET registers a Protocol for Packet capture at the system network layer. Then, all outgoing and incoming packets will be transferred to the forward () function. the outgoing direction (outgoing packet) will be used to capture packets in dev_queue_xmit PF_PACKET, register a protocol at the system network layer. Then, all outgoing and incoming packages will be transferred to the packet_rcv () function i

Simple packet capture Analysis in linux Sometimes we may encounter some problems that require packet capture analysis. When there is no professional packet capture tool at hand, we can use tcpdump instead (this tool is provided in general releases) For example, we need to analyze the

The performance of the test system in Linux has found that the packet loss rate is extremely serious. It sends 210000 pieces of data, and the packet loss rate reaches 110000. The packet loss rate exceeds 50%. In the same case, only a few pieces of data are lost during windows testing. The situation is grim and must be

Linux under the default is to prohibit the forwarding of packets, but in some special occasions need to use this function, so-called forwarding is when the host has more than one NIC, where a packet received a packet, according to the destination IP address of the packet sent to another network card, the network card a

This article analyzes Linux 1.2.13 Original works, reprint please mark http://blog.csdn.net/yming0221/article/details/7541907 For more please refer to the column, address http://blog.csdn.net/column/details/linux-kernel-net.html Author: Yan Ming Note: "(top)", "(bottom)" in the title indicates the data packet transmission direction in the analysis process: "(top)

Production of a Linux device concurrency is relatively large, droped packet more, especially in the running game packets, there is a serious loss of packet phenomenon, suspected network card performance, in the replacement of equipment before the solution through the software method, through some data on the internet to show that this phenomenon, Also may be the

When the ping packet of Linux returns the system ping internet address created on DUP virtual machine, DUP is easy to occur! The virtual machine here is workstation, not esxi. When ping Baidu address 11523921026, return: 64bytesfrom11523921026: icmp_seq1t Linux ping package returns dup vm's new system ping Internet address, it is easy to happen DUP! The virtual m

, BLOCK_IOPOLL_SOFTIRQ, Tasklet_softirq, Sched_softirq, Hrtimer_softirq, RCU_SOFTIRQ,/ * Preferable RCU should always being the last SOFTIRQ */ Nr_softirqs};A soft IRQ is usually registered within the associated subsystem.During kernel initialization, Softirq_init will register TASKLET_SOFTIRQ and HI_SOFTIRQ related processing functions.void __init softirq_init (void) { ... OPEN_SOFTIRQ (TASKLET_SOFTIRQ, tasklet_action); OPEN_SOFTIRQ (HI_SOFTIRQ, tasklet_hi_action);

ports the current system launchesAnd[[email protected] ~]# Netstat-an//Print network connection Status TCP Three handshake four wave, need to focus on the content;Https://wenku.baidu.com/view/91793c1ec281e53a5802ff29.htmlShare the skill to see the number of all States (client and server in the number of communications, within 1000 is normal) [Email protected] ~]# Netstat-an | awk '/^tcp/{++sta[$NF]} END {for (key in STA) print key, "\ T", Sta[key]} 'LISTEN 9Established 1

of processes because grep itself is a process. Four: View network status To print information such as network connection status, ports that are open to the system, routing tables, and so on. Common commands: NETSTAT-LNP print which ports the current system launches Netstat-an Print network connection status Tips: Netstat-an |awk '/^tcp/{++sta[$NF]} END {for (key in STA) print key, "\ T", Sta[key]} ' count the number of processes in all States focus on the number of established V:

Linux Kernel IPV6 UFO Packet Processing Denial of Service Vulnerability Release date:Updated on: Affected Systems:Linux kernel 3.4.xLinux kernel 3.2.xLinux kernel 3.11.xLinux kernel 3.10.xLinux kernel 3.0.xLinux kernel 2.6.xDescription:--------------------------------------------------------------------------------CVE (CAN) ID: CVE-2013-4387 Linux is the kernel o

'A=12Print ("You want to dry ha%s"%i) or multiple print ("You want to dry ha%s%d"% (i,a))Running results you're going to eat.%s is a placeholder for the string type behind the%i is a defined variable%d placeholder is an integer type%.2f placeholder is a floating-point type5. Type castingsuch as name = input (' input name ') (input default type is string shape)name = Int (name) cast to integral typeWriting code is very logical.Requirements: Write a login program, the maximum number of failures i