That's odd. I am able to get commands to work over SSH without a
password.
I copied the contents of ~/.ssh/id_rsa.pub on my work computer into
~/.ssh/authorized_keys on my home computer. Now I can SSH from my work
computer to my home computer like this:
ssh me@myhomepc date
And it logs into my home computer and then runs the date command. I did
not
have to do anything with the authorized_keys file on my work computer to
make this happen.
That's all appropriate.
You only need to modify authorized_keys in both places if you want the
symmetric relationship that either machine can log into the other.
Correct.
I mentioned that I did not have to alter the authorized_keys file on my work
PC in response to the OP's statement:
I know how to solve the issue, i.e. by cross appending the
authorized_keys files, in order that each machine knows itself. But
there must be a simpler way.
I have no idea why you would need to do something like that. I have never
had to "cross-append" anything in order to make this work. I just wanted to
clarify for the OP that the keys only need to be shared in one direction to
do this.
He seems to indicate that the passwordless login works just fine unless he
tries to run a command through the ssh command line. I don't know why that
would make a difference.
Big difference for me. As I said in my original post, certain
computational parallelized codes (from major supercomputer centers,
latest versions) do not work unless the two machines talking to one
another also know themselves. Usually, the "two machines" are my
desktop (let say deb32) and my parallel computer (let say deb64)
talking to one another via a router.The only way I found (perhaps
suggested by the author of the code, I don't remember) to login
passwordless (my arrangement is also passfraseless) to the parallel
computer - and vice versa - while requesting the date, is to take the
deb32 keys from deb64 and append them to those of deb32 itself, and
vice versa. I admit that most codes do not care about that, but it
happens that I am using "at this very moment" a code that has such
idiosyncrasy.
When I said "there must be a simpler way", I meant to make that
appending intrinsic in the configuration of ssh. Otherwise, I have to
stay to ssh if I want (as I need) also to access supercomputers.
I am surprised that others are able to login while running a command
by simply sending "one-way" the keys. As I am no system expert, I
assume that I am not setting up correctly ssh.
regards
francesco