Blockchain Security Training Network and Node Security 3 — Questions and Answers
Question 1: A BGP hijack reroutes a mining pool's traffic through an attacker. What category does this fall under?
- Network-layer routing attack (Correct answer)
- Smart contract reentrancy
- Private key brute force
- Front-running
Correct answer: Network-layer routing attack
BGP hijacking manipulates internet routing to intercept or partition blockchain traffic at the network layer.
Question 2: What is the benefit of encrypting peer-to-peer connections between nodes?
- Prevents eavesdropping and traffic tampering (Correct answer)
- Eliminates the need for consensus
- Removes transaction fees
- Increases the coin supply
Correct answer: Prevents eavesdropping and traffic tampering
Encrypted transport stops passive snooping and active modification of messages exchanged between nodes.
Question 3: Which configuration reduces the risk of a node being partitioned from the honest network?
- Maintaining diverse, manually added trusted peers (Correct answer)
- Connecting to a single peer only
- Disabling all outbound connections
- Using one ISP route exclusively
Correct answer: Maintaining diverse, manually added trusted peers
Diverse and trusted peer connections make it harder for an attacker to isolate or eclipse the node.
Question 4: A node's logs show a flood of malformed packets degrading performance. What attack is most likely?
- Denial-of-service (DoS) attack (Correct answer)
- 51% attack
- Time-bandit attack
- Oracle manipulation
Correct answer: Denial-of-service (DoS) attack
A flood of malformed or excessive traffic aimed at exhausting resources is a denial-of-service attack.
Question 5: Why should validator nodes use separate sentry nodes in some networks?
- To shield the validator's IP from direct DoS targeting (Correct answer)
- To increase token rewards
- To skip block validation
- To disable encryption
Correct answer: To shield the validator's IP from direct DoS targeting
Sentry node architecture hides the validator behind proxy nodes, protecting it from direct denial-of-service attacks.
Question 6: What risk arises from running a node on default credentials for its monitoring dashboard?
- Attackers can log in and reconfigure or stop the node (Correct answer)
- It improves uptime
- It speeds up syncing
- It encrypts the disk
Correct answer: Attackers can log in and reconfigure or stop the node
Default credentials are widely known and let attackers take control of the node's management interface.
Question 7: Which approach helps detect a compromised node early?
- Continuous monitoring and alerting on anomalous behavior (Correct answer)
- Disabling all logs
- Ignoring peer counts
- Turning off updates
Correct answer: Continuous monitoring and alerting on anomalous behavior
Monitoring metrics and alerting on anomalies enables early detection of compromise or attack.
Blockchain Security Training Network and Node Security 3
A BGP hijack reroutes a mining pool's traffic through an attacker.
What category does this fall under?