我是一名网络学生，现在正在研究 nmap，我不明白为什么我在这种扫描类型上得到了不同的 anwser：

如何解决我是一名网络学生，现在正在研究 nmap，我不明白为什么我在这种扫描类型上得到了不同的 anwser：

我现在正在一个网站上学习 nmap 并且我不明白一些事情。当我尝试使用 nmap 使用此命令扫描端口时：

sudo nmap -sS x.x.x.x.

我明白了：

Nmap scan report for x.x.x.x

Host is up (0.011s latency).

Not shown: 992 closed ports

PORT    STATE    SERVICE

21/tcp  open     ftp

22/tcp  open     ssh

53/tcp  filtered domain

80/tcp  open     http

110/tcp open     pop3

139/tcp open     netbios-ssn

143/tcp open     imap

445/tcp filtered microsoft-ds

但是当我尝试像这样使用 -S 命令时：

sudo nmap -sS x.x.x.x -S x.x.x.x -e eth0 -Pn

我明白了：

Nmap done: 1 IP address (0 hosts up) scanned in 1.53 seconds

为什么我没有使用 -S 选项打开端口，但是当我使用 -sS/-sT 选项时，我显示了端口？您通常什么时候使用 -S 选项？

解决方法

这是对这些选项的详细解释，当您阅读它们时，您会明白为什么扫描时没有结果我希望您觉得这个答案有帮助 -S （欺骗源地址）

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-e (使用指定接口)

In some circumstances,Nmap may not be able to determine your source address (Nmap will tell you if this is the case). In this situation,use -S with the IP address of the interface you wish to send packets through.

Another possible use of this flag is to spoof the scan to make the targets think that someone else is scanning them. Imagine a company being repeatedly port scanned by a competitor! The -e option and -Pn are generally required for this sort of usage. Note that you usually won't receive reply packets back (they will be addressed to the IP you are spoofing),so Nmap won't produce useful reports.

-Pn（无 ping）

Tells Nmap what interface to send and receive packets on. Nmap should be able to detect this automatically,but it will tell you if it cannot.