Port Scanning with Nmap

Introduction

NMAP can tell us about the device information and application information

Challenge of the day

Guessing the types of Server with Nmap Port Scanning

(A) active fingerprinting

(B) passive fingerprinting

(C) Dashboard Monitoring

How does Port Scanning Works?

(1) The scanner send a TCP SYN to the target to start a connection on port#0. (2a) If this port is opened on the target, it will reply TCP SYN+ACK back to the scanner. From here, the scanner knows that this port#0 is opened on the target host. (2b) If the port is not opened, the target host sends RST back to the scanner. From here, the scanner knows that this port#0 is closed.(3) Regardless of what target host replies, the scanner always sends RST back to the target to cancel the handshake (since it has never intended to start a real connection in the first place). (4) The scanner repeats steps 1->3 for port#2, port#3...until the last available port number is scanned.
Scanning if Port22 and Port113 is open (Source)

Port Scanning with Nmap

Setting the ‘Target IP’ and the Scan ‘Profile’ — only two parameters are needed to port scan in Zenmap
All the ScanProfiles in Zenmap Explained
Scan results showing TCP ports that are opened in Eagle Server
21/tcp
This means that the ‘normal user’ in the network can use the FTP service on the Eagle server by typing ftp://192.168.238.200 on a browser like Chrome.
23/tcp or 443/tcp
The user can also open a Telnet or SSH connection to Eagle server by typing 192.168.238.200 using putty.exe.
80/tcp
If the user want to see the website hosted in Eagle server, he can type http://192.168.238.200 on a web browser.
6667/tcp
The user can even chat to some other hosts using the IRC service hosted in Eagle server using the IRC client.
25/tcp
Another service that is supported is email service. The user can sends an email to Eagle server (SMTP server). If the receiver is also in the Eagle server domain, then he can receive this email.

What Exactly Happened?

Nmap (Zenmap) scanning all the 1000 popular TCP ports

--

--

--

I’m just a little boy, lost in the tech world. But remember, love is a riddle, and life with tech is more amazing than ever

Love podcasts or audiobooks? Learn on the go with our new app.

Recommended from Medium

Something is rotten in the state of the Darknet

{UPDATE} Video Poker Hack Free Resources Generator

The biggest hack in the history of Crypto: How it happened!

{UPDATE} Batak HD Online Hack Free Resources Generator

The Rise of Facial Recognition Technology

Dirty Pipe: CVE-2022–0847 Tryhackme Writeup

What is the Zero-Trust-Model?

Digital Rights Ireland and communications surveillance in the EU

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store
Avocado Aun

Avocado Aun

I’m just a little boy, lost in the tech world. But remember, love is a riddle, and life with tech is more amazing than ever

More from Medium

PicoCTF_2022 \\ Basic Mod 37 \\ Cryptography

RCE on micro_httpd web server

CSRF prevention: Control your TLDs

San Diego CTF 2022 — Six-Bites