// HACKER NEWS — CYBERSECURITY
The Cables That Connect the World
We treat the internet as if it were air, ambient and ownerless, when in
reality, however, it is the exact opposite. This is a look at what
connects the world, and who builds and owns that infrastructure.
At the northeastern edge of La Línea de la Concepción, on a scrubby
Mediterranean beach called El Burgo–Torrenueva, there is an old
battlement-tower, La Torre Nueva, and not much else. It was part of the system
of coastal watchtowers during the 16th century that would defend the area
against the incursion of the Barbary corsairs. The coordinates are
36°12′36″N, 5°19′27″W. Walk the tideline and you would never know that buried
two metres beneath the sand, a fibre-optic cable comes out of the sea here and
turns into the internet. It’s the start of a line that runs across the Strait
of Gibraltar to Ceuta, on the African coast, and on toward two continents.
Nearly everything you do online that crosses an ocean passes through a cable
like this, ending, in most cases, underneath a similarly unremarkable patch of
coast.
Note: Ceuta is an interesting place by itself, that has recently gained
some attention and that would also make for an interesting write-up of its own.
However, the tl;dr is that it is an autonomous Spanish city of some 85,000
people sitting on the North African coast, bordering Morocco, which means the
European Union has one of its very few land borders with the African continent
running straight through a peninsula most people could probably not even point
to on a map.
It has been held by the Spanish crown since 1668, it had been Portuguese before
that, and Morocco seemingly never stopped claiming it. For our purposes,
though, what matters is that the small enclave, until very recently, hung off
the mainland’s network by a single ageing link.
When we talk about the internet we do so as if it were air. Ambient,
ownerless, and everywhere. In reality, however, it is the exact opposite,
because international data doesn’t (normally) travel by, let’s say, satellite,
despite what most people might assume. It travels through roughly 1.5 million
kilometres of very real (and very owned) fibre-optic cable lying on the seabed,
surfacing at a small number of carefully chosen landing points.
For these landing points you normally need a gently sloping seabed, mild
currents, and little marine traffic, so that anchors and trawlers don’t sever
the line. Suitable spots are scarce enough that the same beach usually becomes
the shared landfall for several cable systems at once.
Unlike what you might be thinking of at first, submarine cables
aren’t your run-of-the-mill Ethernet or fibre cable. The hardware that does the
heavy lifting out in the deep ocean is about as thick as a garden hose with
roughly 25mm across and weighing in at around 1.4 tonnes for every kilometre.
The part that carries your data is a small bundle of glass fibres, each one
around the same thickness as human hair, sitting in the very middle.
Everything else wrapped around those fibres is there to keep them alive in a
deeply hostile environment. Working outward from the core, the fibres sit in a
water-blocking gel inside a thin copper or aluminium tube, which is sheathed in
polycarbonate, then an aluminium water barrier, then a layer of stranded steel
wires that give the cable its tensile strength, then a wrap of mylar tape, and
finally an outer skin of polyethylene. The copper is for power, because the
cable doubles as a very long extension lead, which we will get to in a moment.
Closer to shore, where trawlers and anchors roam, the whole thing gets one or
two further jackets of galvanised steel armour wire, swelling it to 50mm or more
in diameter and several times the weight. Hence, the cable that surfaces on our
Spanish beach is buried a couple of metres down and not simply left lying on the
sand.
The reason a copper conductor runs the entire length is that light, no matter
how pure the glass, slowly fades as it travels, and so every 50 to 80 kilometres
th