Which technique involves sending packets with bad or bogus TCP/UDP checksums to bypass certain firewall rule sets?

Which technique involves sending packets with bad or bogus TCP/UDP checksums to bypass certain firewall rule sets?

• A. Anonymizers
• B. Direct TTL Probes
• C. Sending Bad Checksums
• D. Randomizing Host Order

Answer: (C)

The essence of this technique is manipulating the transport-layer integrity check to slip past firewall rules. TCP and UDP packets carry a checksum to validate data integrity, but some firewall implementations rely on header fields or don’t revalidate checksums at the boundary. By sending packets with deliberately invalid checksums, you can bypass certain rule sets that expect valid checksums or that don’t properly inspect the payload when a checksum is bogus. This specific tactic—sending bad or bogus checksums—is why it’s the right choice. The other options describe different approaches (hiding identity, probing for information, or randomizing sources) that don’t hinge on checksum manipulation.

The essence of this technique is manipulating the transport-layer integrity check to slip past firewall rules. TCP and UDP packets carry a checksum to validate data integrity, but some firewall implementations rely on header fields or don’t revalidate checksums at the boundary. By sending packets with deliberately invalid checksums, you can bypass certain rule sets that expect valid checksums or that don’t properly inspect the payload when a checksum is bogus. This specific tactic—sending bad or bogus checksums—is why it’s the right choice. The other options describe different approaches (hiding identity, probing for information, or randomizing sources) that don’t hinge on checksum manipulation.