simulate packet loss

The kernel has a buffer for packets to be delivered to tcpdump. IfTcpdump doesn' t respond quickly enough, the kernel will overwrite oldPackets with new ones.When tcpdump is used to capture packets, the kernel allocates a buffer to store the packets transmitted to tcpdump. If tcpdump is not processed fast enough, the newly arrived packet will overwrite the earlier packet in the buffer, that is, dropped

captured:After this, a question and answer, super harmony.Of course, there is another workaround, that is to let OS X user disable ARP unicast request such an "advanced" feature, disable method is as follows:Open Terminal Terminalsudo su if the power-on password is set, enter the power-on password.touch/etc/sysctl.confecho net.link.ether.inet.arp_unicast_lim=0 >>/etc/sysctl.confchown root:wheel/etc/sysctl.confchmod 0644/etc/sysctl.confturn off the terminal terminalRestart the machine after the

The problem of data packet loss transmitted by php big form using the post method In the production environment, a huge form, including three images, hundreds of input boxes and nearly one thousand checkboxes, is intercepted when The post method is used to submit data to the background.In the production environment, a huge form, including three images, hundreds of input boxes and nearly one tho

Accustomed to TCP programming, it is wrong to think that UDP can handle these problems. A udp application must take full responsibility for reliability, including packet loss, duplication, latency, out-of-order, and connection failure.Generally, we develop and test on a LAN with good reliability and low transmission latency. Some problems are not easy to expose, but errors may occur on the large internet.Th

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

Reprint: http://blog.csdn.net/galaxy_fxstar/article/details/5290498 Recently with tcpdump grab bag, found that there are a large number of drops ("packets dropped by kernel"), As follows: Tcpdump-i eth0 DST Port 1234 and udp-s 2048-x-tt >a.pack Packets Captured3043 Packets received by filter2706 packets dropped by kernel Packet Drop Reason: After Google and analysis, the cause of this drop is due to the libcap caught

For more information, see Database SYS @ LEO1showuserUSERisSYSSYS @ LEO1select * fromv $ version. BANNER -------------------------------------------- For more information, see Database SYS @ LEO1showuserUSERisSYSSYS @ LEO1select * fromv $ version. BANNER -------------------------------------------- More highlights available 1. database version SYS @ LEO1> showuser USER is "SYS" SYS @ LEO1> select * from v $ version; BANNER --------------------------------------------------------------------

This article describes how to use scapy to simulate packets in Python to implement arp attacks and dns amplification attacks. This article focuses on the use of scapy, for more information, see scapy, a powerful interactive data packet processing program written in python. scapy can be used to send, sniff, parse, and forge network data packets, network attacks and tests are often used. Here we will use pyt

whether the domain-controlled DNS Set forwarding address problem, through the Discovery domain control DNS forwarding address for the Singapore address, the basic judgment is a problem, so change the forwarding address for the local ISP DNS, through the test client discovery, All resolved Baidu's IP is the mainland's Baidu server address, and the access speed and ping packets are normal.This troubleshooting let me on the domain control of some basic concepts have a deep understanding, because l

Sometimes I want to discard some packages, such as (audio and video) at some time. I wrote a filter for packet loss. For the Declaration, see the following file. However, during use, when the video is still closed and the stream is opened again, there will still be a picture before it is closed, and the picture after it is turned on will pop up. I wonder if you have any better solutions. Filter will be

before using Eclipse to test MAVEN's Web project, you can automatically publish your workspace's Web project code to "F:\IWorkspace\.metadata\" by clicking on "Clean" in the Eclipse internal Tomcat right button. Plugins\org.eclipse.wst.server.core\tmp2\wtpwebapps "This path is very convenient. If the war package deployed in Tomcat chooses the "Add External Web Module", then the test is going to cry. The MAVEN command is used before each test to repackage, the process of packaging is not only ver

Before using Eclipse to test MAVEN's Web project, you can automatically publish your workspace's Web project code to the F:\IWorkspace\.metadata\.plugins\ by clicking "Clean" on the inside of the Eclipse Tomcat right button. Org.eclipse.wst.server.core\tmp2\wtpwebapps "This path is very convenient. If the war package deployed in Tomcat chooses the "Add External Web Module", then the test is going to cry. The MAVEN command is used before each test to repackage, the process of packaging is not onl

The simulated server suddenly loses power, the database is lost, and the transaction cannot be recovered from the rollback failure.The database status is as follows:SQL> select instance_name, status from v $ instance;INSTANCE_NAME STATUS----------------------------Marven OPENNon-archive mode:SQL> archive log listDatabase log mode No Archive ModeAutomatic archival DisabledArchive destination/u01/app/Oracle/product/10.2.0/db_1/dbs/archOldest online log sequence 25Current log sequence 27 SQL gt; s

Analysis of the causes of UDP packet loss in Linux system kernel1. UDP Checksum ErrorPhenomenon: You can use NETSTAT-SU to see that there is a UDP error packet.Tcpdump catch packet, open the captured UDP message in Wireshark, turn on checksum option, error packet.Scenario: Finding link Failure www.ahlinux.com2, Firewall OpenSymptom: A package for a specific port

, we set the maximum limit of 4,096, is the driver inside each receive a batch of packets, it will ixgbe_alloc_rx_buffers assign a batch of new SKB and pagePCI_DMA mapping to the hardware to collect packetsHere the first Tasklet dispatch to CPU1, cpu2 the problem can be explained, the VM packet triggered the network card cpu1, cpu2 on the interruption, until soft interrupt, KFREE_SKB, Trigger Idx_release, then tasklet_schedule, then TX _action has bee

FEC (Forward error Correction) forward error correction UDP\RTP used to improve wireless and other network packet loss problems The algorithm is not introduced at this stage. Idea: FEC ENCODE adds redundant packets, and when the wireless network drops packets, the receiver uses redundant packets to decode the lost packets. Example: 10 packets, the code will add 2 packets, a total of 12 packets sent to th