ACM Reference format:

1 INTRODUCTION

2 PATH VALIDATION: WHAT AND WHY
2.1 Out of Source, Out of Control: Packet Forwarding under Internet's Status Quo
2.2 My Packet, My Way: That's when You Can't Count on Current Internet
2.3 Path Validation = Path Enforcement + Path Verification

3 THE ROAD TO PATH VALIDATION
3.1 What's (Definitely) Not Path Validation
3.2 What's One Step Closer: Path Verification
3.3 What's Almost There: Path Enforcement

4 FINALLY, PATH VALIDATION: PATH ENFORCEMENT + PATH VERIFICATION
4.1 Rationale: PFRI
4.2 ICING
4.3 OPT
4.4 OSV

5 WHAT'S BEYOND: ALIBI ROUTING

6 WHAT'S TO UNFOLD: OPEN ISSUES AND FUTURE DIRECTIONS
6.1 Formal Security Proof
6.2 Packet Processing Attestation
6.3 Hidden-Node Attack
6.4 Host Anonymity and Path Privacy
6.5 Forwarding Agility

7 CONCLUSION