SSH again!

["Timothy C. Phan" <tphan@iqrinc.com>]

hi All,

  I'm still confused about the keys file.

  I ran the ssh-keygen on machine-1 with passphrase
  and it created two files in
    $HOME/.ssh/identify
    $HOME/.ssh/identify.pub

  I copy the identify.pub to machine-2:$HOME/.ssh/m1.key
  on machine-2,  I ran the command on machine-2 to logon
  machin-1:

     ssh -i $HOME/.ssh/m1.key machine-1

  and I got this message:

    The authenticity of host'machine-1' can't be established.
    Key fingerprint is .... .... ...
    Are you sure you want to continue connecting (yes/no)

  If I replied yes,  it will create a file in $HOME/.ssh/known_hosts
  and I'll be able to connect after the supplying
  the login password (no the passphrase from the ssh-keygen) 
  to the login prompt.

  If I ran the ssh without specifying the -i m1.key, I can
  still logon to the machine-1. 

  So my question is that what are the keyfile(s) used for?
  Or did I do something stupid ?

  Thanks in advance!

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tcp