Ask HN: How to monitor a sea fiber cable? | Hacker News Reader

Ask HN: How to monitor a sea fiber cable?

4 pointsanuragpeshne3 comments

Recently there was a news[0] about how a national intelligence agency tried to monitor data transmitted via a sea fiber optic cable called SAFE[1] on a foreign country.

Keeping aside the politics, is it feasible to monitor and sniff data out the sea fiber directly?

Wikipedia says the cable transmits data at 440Gb/s. So I'm assuming they cannot store a large portion of the data for future analysis. Further, since this was carried in a foreign country, they might not have access to a data center, nor they can transmit it back to the home country (it would need bandwidth of another sea cable). And lastly, I'm guessing most of the traffic must be encrypted.

So how are they doing it? If the news is incorrect, it is even possible to do it for anyone with "a device" that be taken to a foreign country in a plane?

0: https://www.msn.com/en-in/news/other/mauritius-snooping-scandal-%E2%80%94-the-moustache-man-from-india-in-the-centre-of-the-storm/ar-AAZVzrB

1: https://en.wikipedia.org/wiki/SAFE_(cable_system)

Yes, it's possible.

Yes, it's being done.

Yes, they have compute capable of analyzing live traffic at those data rates.

The two methods I know of are:

1. Cutting the fiber and installing a splitter. This could be done during a "normal" maintenance window, in cooperation with the fiber owner. Traffic would just flow over another line.

Eg. https://en.wikipedia.org/wiki/Room_641A

2. Leaving the fiber intact, but bending the fiber and reading light emanations. This technique has been done for decades. You'll have negligible attenuation.

Examples of these technique were described in the James Bamford books, Body of Secrets and The Shadow Factory.

https://en.wikipedia.org/wiki/Body_of_Secrets

https://en.wikipedia.org/wiki/The_Shadow_Factory

IIRC, the book Blind Man's Bluff describes a US submarine mission sneaking into a real hairy area (I want to say the Black Sea?) and applying method #2 to some Russian fiber.

https://www.amazon.com/Blind-Mans-Bluff-Submarine-Espionage/...

Do have any details about the compute or how they do it?

This official report from the EU has useful technical details on how the US' NSA does (did?) it using fiber optic splitters at the landing stations and possibly even undersea. Storage and DPI is done in local caches. Gives an idea of how it could be done.

https://surveille.eui.eu/wp-content/uploads/sites/19/2015/04...

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