The simple answer is
ssh username@hostname
Enter your password and you are set. My problem is that I wish to connect to a computer in my university. There are several machines which everyone can access but before doing so we have to go through the login machine. So say the name of the login machine is login.school.edu
Then I would do
ssh login.school.edu
From there then I would ssh to one of the several machine names
ssh ld00
They have 112 machines, so I can do ld00 through ld112. The reason I'm asking this is because I want to run the Mathematica Kernel in one of these machines but in the Kernel configuration it asks for the hostname. The hostname cannot be the login machine because this machine does not have Mathematica installed and this machine wasn't meant for computations. Any way I can bypass this?
Update:
So it seems that those machines are not public in the internet. Now that I'm in the deparment I connected to the network and now I can do a simple
ssh username@hostname
The administrator of the machines did say something interesting:
I do not know what SSH implementation is currently part of MacOS. Under OpenSSH (used on Linux machines) it is theoretically possible to make creative use of the ProxyCommand directive to make it appear as if those hosts are directly available to SSH. I cannot tell you how to do this, however; I've only seen mention of it.
So, does anyone know how to do this so that I can connect to the kernel from outside the school?