ssh, sftp, and public key authentication

[Erik Norgaard]

dave wrote:
> Hello,
>     I've got a machine i use public keys on to which i'm trying to ssh. When
> i created a key for this user i did not define a passphrase, yet i am being
> asked for one when i ssh in to the box. I use the command ssh -i
> <filename.pub> hostname however if i do sftp username at hostname i'm allowed
> in no questions asked.
>     Help needed!

This is typically a problem with the key not being exported properly. By 
default ssh falls back to normal password authentication. You can 
configure ssh only to allow keys for extra security.

You need to export the key to the destination host like this:

$ scp .ssh/<filename.pub> username at hostname:
$ ssh hostname
$ cat <filename.pub> >> .ssh/authorized_keys

Now since username does not have access to hostname yet, you can mail or 
send by other means the public key - it's public, not secret - and have 
the admin do

# cat <filename.pub> >> ~username/.ssh/authorized_keys

Some errors I have seen is spelling authorized_keys in british english.

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