On 03/09/2016 10:53 PM, Sam Norris wrote:
Why does Facebook spoof the source IP address of the hop before this server? They spoof the source IP address that is performing the traceroute. ... (31.13.28.207) 67.846 ms ae12.dr08.ash3.tfbnw.net (31.13.29.191) 68.629 ms 12 * * * 13 * * * 14 8.25.38.1 (8.25.38.1) 68.571 ms 68.718 ms 68.132 ms 15 edge-star-mini-shv-07-ash4.facebook.com (66.220.156.68) 67.903 ms 67.752 ms 68.071 ms ---
Hop 14 is the source ip of the traceroute which is forged. This essentially makes hop 14 reply using the same ip for src and dst.
If intentional, I would speculate that this might be something to help their support staff by giving them confirmation of where the traceroute actually originated from in the public Internet view given that the originator might actually be behind possibly several layers of NAT. The two missing hops could be a marker or perhaps other info that got eaten due to various source filters? -- Brandon Martin