User A on box foo: foo> ssh-agent xterm foo> ssh-add
* enters their pass key * User A can now ssh to any box that has their public key in box:$HOME/.ssh/authorized_keys
User B (evul hacker with root on box foo): foo# SSH_AGENT_PID=XXXX; export SSH_AGENT_PID foo# SSH_AUTH_SOCK=/tmp/ssh-YYYY/ZZZZ; export SSH_AUTH_SOCK User B now can ssh to any box that User A can, as above. (where XXXX, YYYY, and ZZZZ are determined by evul hacker)
I once read a 'gravitional push' theory somewhere on the web which was quite interesting. Unfortunately I can't find it now but I'll try to explain it as far as I can remember it:
Imagine the universe as a giant hollow sphere. From every point on the interior surface of this sphere is a light source, which emits light in every direction internal to the sphere. So at every point inside the sphere there is an even distribution of light travelling in all directions (this light represents something which theoretically pervades all of space, which may or may not be a form of electromagnetic radiation).
Now imagine a small solid sphere somewhere inside the larger sphere, which represents a body of matter in the universe. The light strikes this sphere from all directions and exerts a force on it - but all the forces are cancelled out due to the uniform nature of the light which exerts force from all angles, so the body remains at rest. The object partially blocks light travelling through it, depending on the size and density of the object (heavier objects block more light).
Add another small spherical body to this universe. Now there will exist a kind of 'penumbra' between the two objects, due to the eclipting effect the two objects have on the uniform light. The forces acting on the opposite sides of the objects will no longer cancel, which causes the objects to be pushed towards each other - hence gravitation attraction.
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Here's a summary for you:
User A on box foo:
foo> ssh-agent xterm
foo> ssh-add
* enters their pass key *
User A can now ssh to any box that has their public key in box:$HOME/.ssh/authorized_keys
User B (evul hacker with root on box foo):
foo# SSH_AGENT_PID=XXXX; export SSH_AGENT_PID
foo# SSH_AUTH_SOCK=/tmp/ssh-YYYY/ZZZZ; export SSH_AUTH_SOCK
User B now can ssh to any box that User A can, as above.
(where XXXX, YYYY, and ZZZZ are determined by evul hacker)
I once read a 'gravitional push' theory somewhere on the web which was quite interesting. Unfortunately I can't find it now but I'll try to explain it as far as I can remember it:
Imagine the universe as a giant hollow sphere. From every point on the interior surface of this sphere is a light source, which emits light in every direction internal to the sphere. So at every point inside the sphere there is an even distribution of light travelling in all directions (this light represents something which theoretically pervades all of space, which may or may not be a form of electromagnetic radiation).
Now imagine a small solid sphere somewhere inside the larger sphere, which represents a body of matter in the universe. The light strikes this sphere from all directions and exerts a force on it - but all the forces are cancelled out due to the uniform nature of the light which exerts force from all angles, so the body remains at rest. The object partially blocks light travelling through it, depending on the size and density of the object (heavier objects block more light).
Add another small spherical body to this universe. Now there will exist a kind of 'penumbra' between the two objects, due to the eclipting effect the two objects have on the uniform light. The forces acting on the opposite sides of the objects will no longer cancel, which causes the objects to be pushed towards each other - hence gravitation attraction.