nmap 端口扫描王，查看端口是否可访问，是否对外开放

NMap，也就是Network Mapper，最早是Linux下的网络扫描和嗅探工具包。

1 安装

apt-get install nmap

2 使用,查看ip下所有对外的端口

$ sudo nmap -sS ip

Starting Nmap 7.01 ( https://nmap.org ) at 2018-11-16 18:29 CST
Nmap scan report for ip
Host is up (0.038s latency).
Not shown: 997 filtered ports
PORT     STATE  SERVICE
22/tcp   open   ssh
80/tcp   open   http
3389/tcp closed ms-wbt-server

Nmap done: 1 IP address (1 host up) scanned in 31.47 seconds

可以看到 22端口，80端口，3389端口对外开放了。
可以看到状态是打开还是关闭的。
可以看到对应的服务是什么类型的。

也可以查看具体的端口是否对外开放。

 nmap ip -p80

Starting Nmap 7.01 ( https://nmap.org ) at 2018-11-16 18:34 CST
Nmap scan report for ip
Host is up (0.036s latency).
PORT   STATE SERVICE
80/tcp open  http

Nmap done: 1 IP address (1 host up) scanned in 0.12 seconds

$ nmap ip -p 80

Starting Nmap 7.01 ( https://nmap.org ) at 2018-11-16 18:35 CST
Nmap scan report for ip
Host is up (0.036s latency).
PORT   STATE SERVICE
80/tcp open  http

Nmap done: 1 IP address (1 host up) scanned in 0.11 seconds

还可以查范围的。

$ nmap 39.106.106.11 -p 80-4000

Starting Nmap 7.01 ( https://nmap.org ) at 2018-11-16 18:36 CST
Nmap scan report for 39.106.106.11
Host is up (0.038s latency).
Not shown: 3919 filtered ports
PORT     STATE  SERVICE
80/tcp   open   http
3389/tcp closed ms-wbt-server

Nmap done: 1 IP address (1 host up) scanned in 11.74 seconds

基本可以替代了 telnet

$ telnet ip port
Trying ip...
Connected to ip...