how to share Linux user passwords and Samba passwords

Question

I have set up a Linux system with its own user account administration. It is not part of any domain (other than DNS). Now I want to allow its users to mount their home directories on a Windows system.

One way of doing this is by keeping two user account administrations: one maintained with passwd, the other with smbpasswd. This seems needlessly complicated. I want to maintain just one.

How can I best arrange this? The system is running Ubuntu 12.04 (Desktop).

Answer 1

Use PAM's support module for /etc/passwd.

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Update:

There is a fundamental reason why you cannot unify these authentication mechanisms in any simple way.

• Unix and Linux /etc/passwd authentication requires that the user's password be presented to the server. This can be within an encrypted channel (as in SSH password authentication when not using private-key authentication).
• NTLM and MS-Kerberos authentication don't transmit passwords they transmit a hash of a password and the authenticating server takes it's copy of the user's password, constructs a hash using the same algorithm and compares the hash result with the hash presented by the client. Since /etc/passwd doesn't store passwords and uses a different hashing algorithm, /etc/passwd has insufficient information for authenticating NTLM/Kerberos clients.
• Really old SMB authentication protocols pass the password (in plaintext, i.e. unprotected) and a SMB server can therefore compute a /etc/passwd type hash of this and compare it to the hash stored in /etc/passwd.

From the above it follows that you need a separate file to store passwords (smbpasswd) or a domain controller if you want to avoid plain text passwords transiting your LAN.