smbpasswd

Name

smbpasswd — The Samba encrypted password file

Synopsis

smbpasswd

DESCRIPTION

This tool is part of the samba(7) suite.

smbpasswd is the Samba encrypted password file. It contains + the username, Unix user id and the SMB hashed passwords of the + user, as well as account flag information and the time the + password was last changed. This file format has been evolving with + Samba and has had several different formats in the past.

FILE FORMAT

The format of the smbpasswd file used by Samba 2.2 + is very similar to the familiar Unix passwd(5) + file. It is an ASCII file containing one line for each user. Each field + ithin each line is separated from the next by a colon. Any entry + beginning with '#' is ignored. The smbpasswd file contains the + following information for each user:

name

This is the user name. It must be a name that + already exists in the standard UNIX passwd file.

uid

This is the UNIX uid. It must match the uid + field for the same user entry in the standard UNIX passwd file. + If this does not match then Samba will refuse to recognize + this smbpasswd file entry as being valid for a user. +

Lanman Password Hash

This is the LANMAN hash of the user's password, + encoded as 32 hex digits. The LANMAN hash is created by DES + encrypting a well known string with the user's password as the + DES key. This is the same password used by Windows 95/98 machines. + Note that this password hash is regarded as weak as it is + vulnerable to dictionary attacks and if two users choose the + same password this entry will be identical (i.e. the password + is not "salted" as the UNIX password is). If the user has a + null password this field will contain the characters "NO PASSWORD" + as the start of the hex string. If the hex string is equal to + 32 'X' characters then the user's account is marked as + disabled and the user will not be able to + log onto the Samba server.

WARNING !! Note that, due to + the challenge-response nature of the SMB/CIFS authentication + protocol, anyone with a knowledge of this password hash will + be able to impersonate the user on the network. For this + reason these hashes are known as plain text + equivalents and must NOT be made + available to anyone but the root user. To protect these passwords + the smbpasswd file is placed in a directory with read and + traverse access only to the root user and the smbpasswd file + itself must be set to be read/write only by root, with no + other access.

NT Password Hash

This is the Windows NT hash of the user's + password, encoded as 32 hex digits. The Windows NT hash is + created by taking the user's password as represented in + 16-bit, little-endian UNICODE and then applying the MD4 + (internet rfc1321) hashing algorithm to it.

This password hash is considered more secure than + the LANMAN Password Hash as it preserves the case of the + password and uses a much higher quality hashing algorithm. + However, it is still the case that if two users choose the same + password this entry will be identical (i.e. the password is + not "salted" as the UNIX password is).

WARNING !!. Note that, due to + the challenge-response nature of the SMB/CIFS authentication + protocol, anyone with a knowledge of this password hash will + be able to impersonate the user on the network. For this + reason these hashes are known as plain text + equivalents and must NOT be made + available to anyone but the root user. To protect these passwords + the smbpasswd file is placed in a directory with read and + traverse access only to the root user and the smbpasswd file + itself must be set to be read/write only by root, with no + other access.

Account Flags

This section contains flags that describe + the attributes of the users account. This field is bracketed by + '[' and ']' characters and is always 13 characters in length + (including the '[' and ']' characters). + The contents of this field may be any of the following characters: +

U - This means + this is a "User" account, i.e. an ordinary user.
N - This means the + account has no password (the passwords in the fields LANMAN + Password Hash and NT Password Hash are ignored). Note that this + will only allow users to log on with no password if the + null passwords parameter is set in the + smb.conf(5) config file.
D - This means the account + is disabled and no SMB/CIFS logins will be allowed for this user.
X - This means the password + does not expire.
W - This means this account + is a "Workstation Trust" account. This kind of account is used + in the Samba PDC code stream to allow Windows NT Workstations + and Servers to join a Domain hosted by a Samba PDC.

Other flags may be added as the code is extended in future. + The rest of this field space is filled in with spaces. For further + information regarding the flags that are supported please refer to the + man page for the pdbedit command.

Last Change Time

This field consists of the time the account was + last modified. It consists of the characters 'LCT-' (standing for + "Last Change Time") followed by a numeric encoding of the UNIX time + in seconds since the epoch (1970) that the last change was made. +

All other colon separated fields are ignored at this time.

VERSION

This man page is correct for version 3.0 of + the Samba suite.

AUTHOR

The original Samba software and related utilities + were created by Andrew Tridgell. Samba is now developed + by the Samba Team as an Open Source project similar + to the way the Linux kernel is developed.

The original Samba man pages were written by Karl Auer. + The man page sources were converted to YODL format (another + excellent piece of Open Source software, available at + ftp://ftp.icce.rug.nl/pub/unix/) and updated for the Samba 2.0 + release by Jeremy Allison. The conversion to DocBook for + Samba 2.2 was done by Gerald Carter. The conversion to DocBook XML 4.2 + for Samba 3.0 was done by Alexander Bokovoy.