[Introduction] As the saying goes: A thousand-mile embankment is destroyed by an ant nest. Once a small vulnerability is discovered by an attacker, the final consequence may be the paralysis of the entire network. And how to discover security vulnerabilities in corporate networks? What key technologies need to be mastered and adopted? Is there any more popular and efficient tool that can
As the saying goes: "A thousand-mile dike is destroyed by an ant nest." Once a small vulnerability is discovered by an attacker, the final consequences may be to the entire network. of paralysis. And how to discover security vulnerabilities in corporate networks? What key technologies need to be mastered and adopted? Are there any popular and efficient tools that can be used to assist system administrators in scanning and discovering vulnerabilities?
Enterprise port scanning strategy
1. The purpose of port scanning
For those located in the network For a computer system, a port is a potential communication channel, that is, an intrusion channel. Performing port scanning on the target computer can obtain a lot of useful information to discover system security vulnerabilities. Through it, system users can understand what services the system currently provides to the outside world, thereby providing a reference method for system users to manage the network.
In terms of technical principles, port scanning sends detection packets to the TCP/UDP service port of the target host and records the response of the target host. By analyzing the response to determine whether the service port is open or closed, you can learn the services or information provided by the port. Port scanning can also monitor the operation of the local host by capturing the incoming and outgoing IP packets of the local host or server. It can not only analyze the received data, but also help users discover some inherent weaknesses of the target host without Detailed steps for entering a system will be provided. Generally speaking, the purpose of port scanning is usually one or more of the following:
1. Discover open ports: discover open TCP or UDP ports on the target system;
2. Understand Host operating system information: Port scanning can use the "fingerprint" of the operating system to infer information such as the version of the scanned operating system or application;
3. Understand the software or service version: The software or service version can be determined by " "Flag acquisition" or application fingerprint to identify and obtain;
4. Discover vulnerable software versions: Identify flaws in software and services, thereby helping to launch attacks against vulnerabilities.
Port scanning mainly includes classic scanners (full connection) and so-called SYN (semi-connection) scanners. There are also indirect scans and secret scans. The TCP scanning method establishes a standard TCP connection with the scanned host, so this method is the most accurate and rarely misses or false positives, but is easily detected and recorded by the target host. The SYN method establishes a semi-open connection with the target host, so that it is not easily recorded by the target host. However, the scanning results will cause false negatives. This false negative is serious when the network condition is not good.
2. Quickly install nmap for enterprise port scanning
nmap is a network detection and security scanning program that can be used by system administrators and individuals This software scans large networks to obtain information such as which hosts are running and what services are provided. nmap supports many scanning technologies, such as: UDP, TCP connect(), TCP SYN (half-open scanning), ftp proxy (bounce attack), reverse flag, ICMP, FIN, ACK scanning, Xmas Tree (Xmas Tree), SYN scanning and null scan. nmap also provides some advanced features, such as: detection of operating system type through TCP/IP protocol stack characteristics, secret scanning, dynamic delay and retransmission calculation, parallel scanning, detection of down hosts through parallel ping scanning, decoy scanning, avoidance Open port filtering detection, direct RPC scanning (no port mapping required), fragment scanning, and flexible target and port settings.
In order to improve the performance of nmap in the non-root state, the designers of the software have put in a lot of effort. Unfortunately, some kernel interfaces (such as raw sockets) need to be used in root state. So nmap should be used at root whenever possible.
Running nmap will usually get a list of scanned host ports. nmap will always give the service name of the well known port (if possible), port number, status and protocol information. The status of each port is: open, filtered, unfiltered.
The open status means that the target host can accept the connection using the accept() system call on this port;
The filtered status indicates firewall and packet filtering and other network security software mask this port, preventing nmap from detecting whether it is open.
unfiltered means that the port is closed and there is no firewall/packet filtering software to isolate nmap detection attempts. Normally, the status of a port is basically unfiltered. Only when most of the scanned ports are in the filtered state, the port in the unfiltered state will be displayed.
Depending on the feature options used, nmap can also report the following characteristics of the remote host: operating system used, TCP sequence, user name running the application bound to each port , DNS name, whether the host address is a spoofed address, and other things.
Before using it, we need to download the source code package of the software and install it.
The above is the detailed content of Linux enterprise port scanning practice. For more information, please follow other related articles on the PHP Chinese website!

linux设备节点是应用程序和设备驱动程序沟通的一个桥梁;设备节点被创建在“/dev”,是连接内核与用户层的枢纽,相当于硬盘的inode一样的东西,记录了硬件设备的位置和信息。设备节点使用户可以与内核进行硬件的沟通,读写设备以及其他的操作。

区别:1、open是UNIX系统调用函数,而fopen是ANSIC标准中的C语言库函数;2、open的移植性没fopen好;3、fopen只能操纵普通正规文件,而open可以操作普通文件、网络套接字等;4、open无缓冲,fopen有缓冲。

端口映射又称端口转发,是指将外部主机的IP地址的端口映射到Intranet中的一台计算机,当用户访问外网IP的这个端口时,服务器自动将请求映射到对应局域网内部的机器上;可以通过使用动态或固定的公共网络IP路由ADSL宽带路由器来实现。

在linux中,eof是自定义终止符,是“END Of File”的缩写;因为是自定义的终止符,所以eof就不是固定的,可以随意的设置别名,linux中按“ctrl+d”就代表eof,eof一般会配合cat命令用于多行文本输出,指文件末尾。

在linux中,可以利用“rpm -qa pcre”命令判断pcre是否安装;rpm命令专门用于管理各项套件,使用该命令后,若结果中出现pcre的版本信息,则表示pcre已经安装,若没有出现版本信息,则表示没有安装pcre。

在linux中,交叉编译是指在一个平台上生成另一个平台上的可执行代码,即编译源代码的平台和执行源代码编译后程序的平台是两个不同的平台。使用交叉编译的原因:1、目标系统没有能力在其上进行本地编译;2、有能力进行源代码编译的平台与目标平台不同。

linux查询mac地址的方法:1、打开系统,在桌面中点击鼠标右键,选择“打开终端”;2、在终端中,执行“ifconfig”命令,查看输出结果,在输出信息第四行中紧跟“ether”单词后的字符串就是mac地址。

在linux中,rpc是远程过程调用的意思,是Reomote Procedure Call的缩写,特指一种隐藏了过程调用时实际通信细节的IPC方法;linux中通过RPC可以充分利用非共享内存的多处理器环境,提高系统资源的利用率。


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

Dreamweaver CS6
Visual web development tools

DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software

WebStorm Mac version
Useful JavaScript development tools

Atom editor mac version download
The most popular open source editor

MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.
