IP spoofing is when an attacker sends IP packets with a falsified source IP address. The goal is either to hide the attacker's identity, impersonate a trusted system, or facilitate attacks like DDoS amplification where responses are redirected to a victim.
How IP Spoofing Works
IP headers include a source address field. Operating systems normally fill this with your real IP, but an attacker can craft packets manually with any IP they choose. Network routers do not verify that the source IP matches the sender's actual address.
Common Spoofing Attack Types
| Attack | How Spoofing Is Used |
|---|---|
| DDoS amplification | Attacker sends requests with victim's IP as source. Servers send large responses to the victim. |
| Blind spoofing | Sending commands to a server while pretending to be a trusted IP (used to bypass IP-based access control) |
| MITM | Impersonating another host to intercept communications |
| SYN flood | Spoofed IPs send many connection requests, exhausting server resources |
How to Detect and Prevent IP Spoofing
- BCP38 filtering: ISPs should filter outbound traffic with spoofed source IPs. Many do not, enabling amplification attacks.
- Ingress filtering: Routers block packets with source addresses that do not belong to the inbound interface's network.
- TCP sequence numbers: Spoofing TCP connections is harder because the attacker cannot see the server's sequence numbers.
- Encrypted protocols: TLS prevents MITM even if IPs are spoofed, because the attacker cannot forge the certificate.
People Also Ask
- Is IP spoofing illegal?
- In most countries, yes. IP spoofing for malicious purposes (DDoS attacks, fraud, bypassing security) is illegal under computer crime laws. It is legal in research and controlled testing environments.
Related: DDoS attacks | Firewalls | IP Lookup