PORT SCANNING is a technique to
Aimprove website SEO ranking
Bfind which ports are open on a host
Ccompress data on the wire
Dencrypt traffic in flight
Answer & Solution
Correct answer: B. find which ports are open on a host
1. PORT SCANNING: sends probes to a target's TCP/UDP ports to determine which are OPEN, CLOSED, or FILTERED.
2. COMMON TOOLS: nmap (the standard), masscan (very fast for /0 sweeps), Zmap.
3. TECHNIQUES:
• SYN scan (half-open): doesn't complete handshake; stealth.
• Connect scan: full handshake.
• UDP scan: probes UDP services (DNS, NTP, SNMP).
• Service/version detection: identifies the SOFTWARE running on a port.
4. PEN-TESTERS use port scanning in RECONNAISSANCE; attackers use it to find exploitable services; defenders use it to AUDIT their own attack surface.
5. UNAUTHORISED scanning of others' systems is often ILLEGAL.
_Source: Nmap official documentation + RFC 793._
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