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On 18/07/2013 18:21, Grant wrote: |
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>>>>> My backup user needs a shell on the backup server in order to execute |
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>>>>> rsync and needs to be included in /etc/ssh/sshd_config AllowUsers in |
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>>>>> order to SSH in. My authorized_keys file is locked-down. The second |
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>>>>> field for the user in /etc/shadow is an exclamation point which I |
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>>>>> think means the user can not log in with a password. Should I take |
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>>>>> any additional steps to prevent that user from logging in and not |
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>>>>> being subject to the authorized_keys restrictions? |
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>>>> |
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>>>> What about "PasswordAuthentication no"? |
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>>> |
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>>> Can that be set for a single user? I have a normal user who needs to |
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>>> log in via SSH with a password and a backup user who only needs to run |
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>>> rsync via SSH keys. If not, does the exclamation point in /etc/shadow |
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>>> prevent the user from logging in without the SSH key? |
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>> |
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>> Depends. |
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>> |
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>> The user doesn't have a Unix password, so if the system prompts for one |
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>> it cannot succeed and the login fails. |
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>> |
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>> But sshd has other implementations for authentication to, not just |
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>> classic Unix. If it uses PAM, then PAM could in theory do anything, even |
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>> using AD to authenticate with a password. |
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>> |
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>> So if your sshd config uses Unix passwords and keys ONLY (this is the |
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>> norm), then what you describe above does what you want. To be sure, you |
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>> need to audit sshd_config and your pam setup |
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> |
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> Here is my entire sshd_config: |
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> |
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> PasswordAuthentication no |
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> UsePAM yes |
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> PrintMotd no |
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> PrintLastLog no |
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> Subsystem sftp /usr/lib64/misc/sftp-server |
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> AllowUsers user1 user2 |
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> |
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> That must be the Gentoo-default except for the last line, correct? |
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> How is this config if I want user1 to login with a password and user2 |
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> has no password in /etc/shadow and automatically logs in via |
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> authorized_keys to rsync? |
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Gentoo default uses a conventional PAM setup so set |
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PasswordAuthentication yes |
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PubkeyAuthentication yes |
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and it should work. |
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I don't know of any way to configure per-user auth types in sshd_config |
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itself, so I recommend you define exactly what you want to accomplish: |
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do you want to give one user a password and no key, and the other user a |
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key but no password, and have it just work regardless? This would be the |
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"convenience" approach |
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or do you want to enforce the auth method that a specific user must use? |
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This would be the "security" approach and is considerably more difficult |
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-- |
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Alan McKinnon |
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alan.mckinnon@×××××.com |
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