Live host discovery
Types of scans
ARP, ICMP, TCP, and UDP can detect live hosts. Any response from a host is an indication that it is online.
| Scan Type | Example Command |
|---|---|
| ARP Scan | sudo nmap -PR -sn |
| ICMP Echo Scan | sudo nmap -PE -sn |
| ICMP Timestamp Scan | sudo nmap -PP -sn |
| ICMP Address Mask Scan | sudo nmap -PM -sn |
| TCP SYN Ping Scan | sudo nmap -PS22,80,443 -sn |
| TCP ACK Ping Scan | sudo nmap -PA22,80,443 -sn |
| UDP Ping Scan | sudo nmap -PU53,161,162 -sn |
Options
| Option | Purpose |
|---|---|
| -n | no DNS lookup |
| -R | reverse-DNS lookup for all hosts |
| -sn | host discovery only |