packet tracer

them in the/etc/services file of Linux.FTP-data 20/tcpFTP 21/tcpTelnet 23/tcpSMTP 25/tcp mailWWW 80/tcp HTTP # worldwideweb HTTPWWW 80/udp # Hypertext Transfer ProtocolPop-3 110/tcp # Pop Version 3Pop-3 110/udp In fact, the port number can be used with any services you like to specify, but in order to avoid "finding the wrong door" (unless you deliberately want to hide) people will use some of the more common services (wellKnownServices. However, in the TCP data transmission process, more than

, as determined by target: A. Continue to match next rule B. Make some changes to the packet C. Jump to another chain (that is, start by matching each rule in the chain sequentially) D. Returns the chain that raised the jump (that is, the next rule that continues to match the chain before the jump) E. Drop packet F. Receive packets (i.e. no longer continue to match down, return directly) G. Logging

origin:http://blog.csdn.net/e_wsq/article/details/12835457 For the TCP-based development of the communication program, there is a very important problem to be solved, that is, the packet and unpacking. Since I've been working on network communication programming (about three years), I've been thinking about and improving the way that packets and unpacking are addressed. Here's what I think about this question. If it's wrong, The wrong place, begged ev

Group First, let's look at the concept of the next grouping. The so-called grouping is to divide a packet into smaller packets. For example, for a 10GB packet, it is not always a one-time delivery of the past bar, but it is divided into a number of small packets sent past. Structure diagram for each block of data:File headers are typically descriptive data, such as source and destination addresses, data typ

Transferred from: http://cizixs.com/2018/01/13/linux-udp-packet-drop-debug?hmsr=toutiao.ioutm_medium=toutiao.ioutm_ Source=toutiao.ioRecent work encountered a server application UDP packet loss, in the process of reviewing a lot of information, summed up this article, for more people to refer to.Before we get started, we'll use a graph to explain the process of receiving network messages from a Linux system

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

First, in order to prevent the occurrence of port usage,Pkill-9 python can be used in LinuxUsing Taskkill python in Windows systemsSecond, what is the sticky bag phenomenon1, multiple packages (that is, the execution results of multiple commands) stick together phenomenon, called sticky packet phenomenon2. The code example is as follows:Service-Side code:1 Import Socket2 Import subprocess3 4Phone =Socket.socket (socket.af_inet, socket. SOCK_STREAM)5#

Recently on the million Gigabit network card test, there has been a phenomenon that the Gigabit network card did not appear, Tasklet version of the netback, the VM to carry out the package test, found that vif interrupt default binding on CPU0, but the VM packet run found on the host CPU1, The ksoftirqd of CPU2 is very high.From the previous understanding, the package from NetFront out through the Eventchannel notify trigger the Vif IRQ handler functi

Network packet Detection Packet Capture (sniffer): refers to the behavior of data collection on the network, which needs to be done through the NIC. Three ways to access: BSD Packet Filter (BPF) SVR4 Datalink Provider Interface (DLPI) Linux Sock_packet interface Libpcap Library Installation: Apt-get Install Libpcap-dev Common APIs Capturing data packets

Tags: ber by parameter comparison print replace markdown cause show When you use Sqoop to export data from hive to MySQL, you encounter an exception that is caused by the small max_allowed_packet settings of the exported database.By executing the command in the database: mysql> show variables like ‘max_%packet‘; +--------------------+-----------+ | Variable_name | Value | +--------------------+-----------+ | max_allowed_packet | 268435456 | +

1. Circuit Switching Technology The network switching technology has gone through four stages: Circuit Switching Technology, packet switching technology, group switching technology and ATM technology. Both the Public Telephone Network (PSTN) and the mobile network (including the GSM network and CDMA network) Adopt the circuit switching technology. Its basic feature is that the connection-oriented approach is adopted before both parties can communicate

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