nmap

nmap -sS -sV -A "target_ip"


-sS (TCP SYN scan)

-sV (Version detection)

-A (Aggressive scan options)

Quick scan (default ports):

nmap [target_ip]
Comprehensive scan (all ports):


nmap -p- [target_ip]
Service version detection and OS detection:

nmap -sC -sV -O -p- [target_ip]
Aggressive scan with scripts:

nmap -A -p- [target_ip]
Scan for UDP ports:

nmap -sU -p- [target_ip]
Detect vulnerabilities (using NSE scripts):

nmap --script vuln -p- [target_ip]
Scan for specific port ranges:

nmap -p 1-65535 [target_ip]

# Breakdown of the Command Syntax

nmap -sC -sV -O -sU -A -p 1-65525 [target_ip]
-sC (Default scripts): 
Runs Nmap's default set of scripts, which includes checks for common vulnerabilities and information gathering. This can add processing time for each scanned port.

-sV (Version detection): 
Attempts to determine the version of the services running on open ports. This requires interaction with services and may increase the scan time.

-O (OS detection): 
Uses various techniques to identify the operating system of the target. This can be slow, especially if the target isn't easily fingerprinted.

-sU (UDP scan): 
Scans all specified ports for open UDP services. UDP scanning is inherently slower than TCP scanning because it relies on timeout-based responses. Additionally, scanning a large range (1–65525) for UDP ports can take a very long time.

-A (Aggressive scan): 
Combines -sV, -O, and -sC while enabling traceroute. This makes the scan even more resource-intensive.

-p 1-65525 (Port range): 
Specifies a nearly full range of TCP and UDP ports to scan. Scanning such a large range increases the workload significantly.

10.10.22.55: 
The target IP address.

## Troubleshooting 

Why Did It Freeze the Terminal?
UDP Scanning Over a Large Range:

UDP scanning is notoriously slow because there is no guaranteed response for closed ports, leading to long timeouts. Scanning nearly 65,000 ports with UDP will take a very long time.
Combination of Flags:

## Combining -sC, -sV, -O, and -A results in overlapping functionality and significantly increases scan complexity. For instance:
-A already includes -sC, -sV, and -O, so specifying them redundantly increases workload.

Excessive Port Range:

Scanning almost all ports (1–65525) for both TCP and UDP is computationally expensive and likely caused the terminal to appear unresponsive.
Network Conditions:

If the target has high latency, packet filtering, or rate-limiting, this could significantly slow down the scan.
System Resource Limitation:

Your machine may have run out of CPU, memory, or network bandwidth to handle such an intensive task.
Recommendations

Quick Solution to memory issues

Split the Scan:

Perform TCP and UDP scans separately to reduce complexity.
nmap -sS -p 1-65525 [target_ip]  # TCP Scan
nmap -sU -p 1-65525 [target_ip]  # UDP Scan
Limit the Port Range:

Focus on the most common ports or use Nmap's default port range.
nmap -sC -sV -A -p 1-1000 [target_ip]
Remove Redundancies:

Since -A already includes -sC, -sV, and -O, you can simplify the command.
nmap -A -p 1-1000 [target_ip]
Optimize UDP Scans:

Use the --top-ports option to focus on the most common UDP ports instead of all ports.
nmap -sU --top-ports 100 [target_ip]
Run the Scan in the Background:

Use a tool like screen or tmux to avoid freezing your terminal, or save the output to a file for later review.
nmap -A -p 1-65525 [target_ip] > scan_results.txt
By optimizing the command and avoiding unnecessary complexity, you'll reduce the risk of freezing your terminal and improve scan efficiency.