sshサーバにパスワードなしでログインする方法です。
鍵を生成する
$ ssh-keygen Generating public/private rsa key pair. Enter file in which to save the key (~/.ssh/id_rsa): [デフォルトのまま] Enter passphrase (empty for no passphrase): [パスフレーズを入力] Enter same passphrase again: [パスフレーズを再入力] Your identification has been saved in ~/.ssh/id_rsa. Your public key has been saved in ~/.ssh/id_rsa.pub. The key fingerprint is: $ ls -l .ssh 合計 8 -rw------- 1 who group 1000 2006-11-25 18:40 id_rsa -rw-r--r-- 1 who group 500 2006-11-25 18:40 id_rsa.pub
パスワードなしでログインするには秘密鍵ファイル(id_ras)を生成する時に入力するパスフレーズで[Enter]を指定します。
重要なことは生成した秘密鍵ファイル(id_rsa)の読み込み権限を持っている人は、誰でもパスワードなしのアクセスができてしまうことです。
これには、ローカルマシンのrootにアクセスできる人を含みます。
したがって、自分が唯一rootにアクセスできるユーザでない場合には、常にリスクがあります。
sshサーバ単独で試す
ひとまず、同じマシンにパスワードなしでログインできるか試します。
authorized_keysファイルを作成する。
$ cd ~/.ssh $ touch authorized_keys $ chmod 600 authorized_keys $ ls -l authorized_keys -rw------- 1 who group 0 2006-11-25 19:12 authorized_keys
公開鍵を登録してパスワードアクセスなしでログインできることを確認する。
$ ssh localhost who@localhost's password: Linux who-desktop 2.6.17-10-generic #2 SMP Fri Oct 13 18:45:35 UTC 2006 i686 The programs included with the Ubuntu system are free software; the exact distribution terms for each program are described in the individual files in /usr/share/doc/*/copyright. Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law. Last login: Sat Nov 25 21:27:51 2006 from localhost $ logout Connection to localhost closed. $ cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys $ ssh localhost Linux who-desktop 2.6.17-10-generic #2 SMP Fri Oct 13 18:45:35 UTC 2006 i686 The programs included with the Ubuntu system are free software; the exact distribution terms for each program are described in the individual files in /usr/share/doc/*/copyright. Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law. Last login: Sat Nov 25 21:28:07 2006 from localhost $
この手順を他のマシンでやることで同じように機能します。
パスフレーズの変更
パスフレーズを変更する時には、ssh-keygen -pを使います。
$ ssh-keygen -p Enter file in which the key is (~/.ssh/id_rsa): Key has comment '~/.ssh/id_rsa' Enter new passphrase (empty for no passphrase): [パスフレーズを入力] Enter same passphrase again: [パスフレーズを再入力] Your identification has been saved with the new passphrase. $ ssh localhost Enter passphrase for key '~/.ssh/id_rsa': Linux who-desktop 2.6.17-10-generic #2 SMP Fri Oct 13 18:45:35 UTC 2006 i686 The programs included with the Ubuntu system are free software; the exact distribution terms for each program are described in the individual files in /usr/share/doc/*/copyright. Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law. Last login: Sat Nov 25 21:28:50 2006 from localhost $
