Tag:data packet

  • STM32 Hal library realizes the serial port DMA transceiver mechanism of ping-pong cache and idle interrupt, which can easily run up to 2m baud rate


    preface Direct memory access(Direct Memory Access,DMA), allowing some devices to access data independently without CPU intervention. Therefore, when accessing a large amount of data, using DMA can save considerable CPU processing time. In STM32, the general DMA transmission direction is: memory – > memory, peripherals – > memory, memory – > peripherals. The peripherals here […]

  • Analysis and solution of TCP sticking “packets” problem implementation of golang code


    1、 Introduction to sticking “bags” In socket network programming, it is end-to-end communication,Client port + client IP + server port + server IP + transmission protocolIt forms a connection that can uniquely and clearly identify. In TCP socket programming, the sender and receiver also follow such rules. 1. Possible causes of some characters and garbled […]

  • iptables


    iptables ==============Table:Filter: general filtering function, including input, forward and output. Default optionsNat: used for address translation, mapping, port mapping, etc., including prerouting and postroutingMangle: used to modify specific packets, including prerouting, output, forward, input, postroutingRaw: generally, it is to stop iptables from doing packet connection tracking processing, so as to provide performance, including prerouting and […]

  • Front end – sort out HTTP knowledge system 2


      Why HTTPS   HTTP is inherently clear text, and the whole transmission process is completely transparent. Anyone can intercept, modify or forge request / response messages in the link, and the data is not secure. HTTP alone cannot be solved. It needs to introduce a new HTTPS protocol, which is simply unsafe. What is HTTPS […]

  • Nmap usage guide


    0x00 introduction Is nmap still introduced? Are there any people who don’t know or can’t use nmap? According to my observation, few people can fully and flexibly use nmap. In fact, nmap is no longer the scanner software of the network layer in your eyes. It has evolved into a full-featured security evaluation framework as […]

  • Kali Linux — “network security” — use Wireshark to capture packets of common protocols and analyze the principle


    preface <font color=\999aaa > as an efficient and free packet capturing tool, Wireshark can capture and describe network packets. Its biggest advantage is free, open source and multi platform support. Under the guarantee of GNU General Public License, users can obtain software and code for free, and have the right to modify and customize its […]

  • Linux network packet capturing tool tcpdump


    catalogue 1、 Introduction to tcpdump 2、 Installation & instructions 1) Installation 2) Usage instructions 3、 Tcpdump example 1、 Introduction to tcpdump Tcpdump is a Linux network packet capturing tool。 It allows users to intercept and display tcp/ip and other data packets sent or received from the network connected to the computer. Tcpdump is applicable to […]

  • CTF competition simulation CFS three-layer intranet roaming


    CTF competition simulation CFS three-layer intranet roaming Environmental Science: Three virtual machines, three networks. target 1: , (linux) target 2:, (linux) target 3: (win7) Attackers can only communicate with target 1 Internet Management Visit It was found that it was the version of thinkphp5 TP vulnerability exploitation Using TP5 detection tool Vulnerability […]

  • 1. How to grab Modbus tcp/udp packets in practice


    As an industrial control dog, I actively went to ceiwei after seeing that ceiwei recently released a new tool for Modbus RTU over tcp/udp filtering and monitoringOfficial websiteAfter a look, it turned out to be a Modbus protocol tcp/udp packet capturing tool. You should know that its commmonitor serial port wizard also has this function, […]

  • Nginx operation and maintenance problem research, update if there is a problem~


    Redirection caused by not adding a slash at the end of the path Reference website: CSDN When visiting the following addresses: https://sdri.jtsj.com.cn:1806…Nginx will try to add a slash at the end In fact, it is to start a 301 redirection, but when the port monitored by nginx is inconsistent with the external port, it will […]

  • Uwsgi considerations


    Differences between HTTP, HTTP socket and socket The HTTP and HTTP socket options are completely different. The first generates an additional process and forwards requests to a series of workers (think of it as a form of shield, equivalent to Apache or nginx), while the second sets the worker to use the HTTP protocol natively. […]

  • Linux basic indicator query


    Refer to RedHat documentation https://access.redhat.com/documentation/zh-cn/red_hat_enterprise_linux/7/html/performance_tuning_guide/index Operating system version cat /etc/redhat-release Kernel version uname -r Overall situation of the server Top top 1 view the usage of each CPU CPU usage cat /proc/cpuinfo Vmstat vmstat -n 310 take 10 samples every 3 seconds procs : r: The number of processes running and waiting for CPU time […]