Two faults, opposite directions, both in issue 047.
There was no forward chain, on the reasoning that dropping there stops every
container the runtime allowed. The first half is true; the conclusion was not. A
published port is redirected and then forwarded, so it never reaches the input
chain — the firewall was silent about the ports most worth protecting. The way
through is the one the system being replaced already used: deny by default, then
allow the runtime's own networks explicitly. A forwarded rule matches what the
client originally asked for, because the destination has been rewritten by the
time the chain sees it.
And ssh is now a floor nothing derives. Every other line comes from what is
assigned, which is the point — but a mesh part-way through adopting a machine
has been assigned almost nothing, so what it computed was a chain that shut the
port used to fix it. From the mesh always; from outside on a machine that faces
outward, because that is the way in when the private network is what broke.
Rehearsed on three machines: a docker-published port declared mesh-only is now
reachable from inside the mesh and refused from outside. Before, it was
reachable from both.
jschoubben
c8d8211385