コピー先サーバーにて

ssh-keygen -t dsa

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Generating public/private dsa key pair.
Enter file in which to save the key (/home/[おれ]/.ssh/id_dsa):
/home/[おれ]/.ssh/id_dsa already exists.
Overwrite (y/n)? y
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/[おれ]/.ssh/id_dsa.
Your public key has been saved in /home/[おれ]/.ssh/id_dsa.pub.
The key fingerprint is:
xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx [おれ]@www.my.domain
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コピー元へid_dsa.pub（公開鍵）をコピーして持っていく

scp ~/.ssh/id_dsa.pub [おれ]@おれの.dyndns.org:~/work/.

で、コピーもとへ言って上記コピーしたファイルを
authorized_keysへ追記
cat ~/work/id_dsa.pub >> ~/.ssh/authorized_keys