Hi, I have a debian 6 server (not joined to windows domain) where is running smb sharing. I'm using it to share files with clients Windows 10 (joined to a windows domain) that have smb signing mandatory via group policy. After we applied that group policy to the windows clients, it is not possible to authenticate to the debian 6 server shares using local accounts.
This is the smb.conf file:

#
# Sample configuration file for the Samba suite for Debian GNU/Linux.
#
#
# This is the main Samba configuration file. You should read the
# smb.conf(5) manual page in order to understand the options listed
# here. Samba has a huge number of configurable options most of which
# are not shown in this example
#
# Some options that are often worth tuning have been included as
# commented-out examples in this file.
# - When such options are commented with ";", the proposed setting
# differs from the default Samba behaviour
# - When commented with "#", the proposed setting is the default
# behaviour of Samba but the option is considered important
# enough to be mentioned here
#
# NOTE: Whenever you modify this file you should run the command
# "testparm" to check that you have not made any basic syntactic
# errors.
# A well-established practice is to name the original file
# "smb.conf.master" and create the "real" config file with
# testparm -s smb.conf.master >smb.conf
# This minimizes the size of the really used smb.conf file
# which, according to the Samba Team, impacts performance
# However, use this with caution if your smb.conf file contains nested
# "include" statements. See Debian bug #483187 for a case
# where using a master file is not a good idea.
#

#======================= Global Settings =======================

[global]
client signing = auto
#server signing = disabled

## Browsing/Identification ###

# Change this to the workgroup/NT-domain name your Samba server will part of
workgroup = WORKGROUP

# server string is the equivalent of the NT Description field
server string = %h server

# Windows Internet Name Serving Support Section:
# WINS Support - Tells the NMBD component of Samba to enable its WINS Server
# wins support = no

# WINS Server - Tells the NMBD components of Samba to be a WINS Client
# Note: Samba can be either a WINS Server, or a WINS Client, but NOT both
; wins server = w.x.y.z

# This will prevent nmbd to search for NetBIOS names through DNS.
dns proxy = no

# What naming service and in what order should we use to resolve host names
# to IP addresses
; name resolve order = lmhosts host wins bcast

#### Networking ####

# The specific set of interfaces / networks to bind to
# This can be either the interface name or an IP address/netmask;
# interface names are normally preferred
; interfaces = 127.0.0.0/8 eth0

# Only bind to the named interfaces and/or networks; you must use the
# 'interfaces' option above to use this.
# It is recommended that you enable this feature if your Samba machine is
# not protected by a firewall or is a firewall itself. However, this
# option cannot handle dynamic or non-broadcast interfaces correctly.
; bind interfaces only = yes



#### Debugging/Accounting ####

# This tells Samba to use a separate log file for each machine
# that connects
log file = /var/log/samba/log.%m

# Cap the size of the individual log files (in KiB).
max log size = 1000

# If you want Samba to only log through syslog then set the following
# parameter to 'yes'.
# syslog only = no

# We want Samba to log a minimum amount of information to syslog. Everything
# should go to /var/log/samba/log.{smbd,nmbd} instead. If you want to log
# through syslog you should set the following parameter to something higher.
syslog = 0

# Do something sensible when Samba crashes: mail the admin a backtrace
panic action = /usr/share/samba/panic-action %d


####### Authentication #######

# "security = user" is always a good idea. This will require a Unix account
# in this server for every user accessing the server. See
# /usr/share/doc/samba-doc/htmldocs/Samba3-HOWTO/ServerType.html
# in the samba-doc package for details.
security = user

# You may wish to use password encryption. See the section on
# 'encrypt passwords' in the smb.conf(5) manpage before enabling.
encrypt passwords = true

# If you are using encrypted passwords, Samba will need to know what
# password database type you are using.
passdb backend = tdbsam

obey pam restrictions = yes

# This boolean parameter controls whether Samba attempts to sync the Unix
# password with the SMB password when the encrypted SMB password in the
# passdb is changed.
unix password sync = yes

# For Unix password sync to work on a Debian GNU/Linux system, the following
# parameters must be set (thanks to Ian Kahan <<kahan@informatik.tu-muenchen.de> for
# sending the correct chat script for the passwd program in Debian Sarge).
passwd program = /usr/bin/passwd %u
passwd chat = *Enter\snew\s*\spassword:* %n\n *Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* .

# This boolean controls whether PAM will be used for password changes
# when requested by an SMB client instead of the program listed in
# 'passwd program'. The default is 'no'.
pam password change = yes

########## Domains ###########

# Is this machine able to authenticate users. Both PDC and BDC
# must have this setting enabled. If you are the BDC you must
# change the 'domain master' setting to no
#
; domain logons = yes
#
# The following setting only takes effect if 'domain logons' is set
# It specifies the location of the user's profile directory
# from the client point of view)
# The following required a [profiles] share to be setup on the
# samba server (see below)
; logon path = \\%N\profiles\%U
# Another common choice is storing the profile in the user's home directory
# (this is Samba's default)
# logon path = \\%N\%U\profile

# The following setting only takes effect if 'domain logons' is set
# It specifies the location of a user's home directory (from the client
# point of view)
; logon drive = H:
# logon home = \\%N\%U

# The following setting only takes effect if 'domain logons' is set
# It specifies the script to run during logon. The script must be stored
# in the [netlogon] share
# NOTE: Must be store in 'DOS' file format convention
; logon script = logon.cmd

# This allows Unix users to be created on the domain controller via the SAMR
# RPC pipe. The example command creates a user account with a disabled Unix
# password; please adapt to your needs
; add user script = /usr/sbin/adduser --quiet --disabled-password --gecos "" %u

# This allows machine accounts to be created on the domain controller via the
# SAMR RPC pipe.
# The following assumes a "machines" group exists on the system
; add machine script = /usr/sbin/useradd -g machines -c "%u machine account" -d /var/lib/samba -s /bin/false %u

# This allows Unix groups to be created on the domain controller via the SAMR
# RPC pipe.
; add group script = /usr/sbin/addgroup --force-badname %g

########## Printing ##########

# If you want to automatically load your printer list rather
# than setting them up individually then you'll need this
# load printers = yes

# lpr(ng) printing. You may wish to override the location of the
# printcap file
; printing = bsd
; printcap name = /etc/printcap

# CUPS printing. See also the cupsaddsmb(8) manpage in the
# cupsys-client package.
; printing = cups
; printcap name = cups

############ Misc ############

# Using the following line enables you to customise your configuration
# on a per machine basis. The %m gets replaced with the netbios name
# of the machine that is connecting
; include = /home/samba/etc/smb.conf.%m

# Most people will find that this option gives better performance.
# See smb.conf(5) and /usr/share/doc/samba-doc/htmldocs/Samba3-HOWTO/speed.html
# for details
# You may want to add the following on a Linux system:
# SO_RCVBUF=8192 SO_SNDBUF=8192
# socket options = TCP_NODELAY


# The following parameter is useful only if you have the linpopup package
# installed. The samba maintainer and the linpopup maintainer are
# working to ease installation and configuration of linpopup and samba.
; message command = /bin/sh -c '/usr/bin/linpopup "%f" "%m" %s; rm %s' &

# Domain Master specifies Samba to be the Domain Master Browser. If this
# machine will be configured as a BDC (a secondary logon server), you
# must set this to 'no'; otherwise, the default behavior is recommended.
# domain master = auto

# Some defaults for winbind (make sure you're not using the ranges
# for something else.)
; idmap uid = 10000-20000
; idmap gid = 10000-20000
; template shell = /bin/bash

# The following was the default behaviour in sarge,
# but samba upstream reverted the default because it might induce
# performance issues in large organizations.
# See Debian bug #368251 for some of the consequences of *not*
# having this setting and smb.conf(5) for details.
; winbind enum groups = yes
; winbind enum users = yes

# Setup usershare options to enable non-root users to share folders
# with the net usershare command.

# Maximum number of usershare. 0 (default) means that usershare is disabled.
; usershare max shares = 100

#======================= Share Definitions =======================

[homes]
comment = Home Directories
browseable = no

# By default, the home directories are exported read-only. Change the
# next parameter to 'no' if you want to be able to write to them.
read only = no

# File creation mask is set to 0700 for security reasons. If you want to
# create files with group=rw permissions, set next parameter to 0775.
create mask = 0777

# Directory creation mask is set to 0700 for security reasons. If you want to
# create dirs. with group=rw permissions, set next parameter to 0775.
directory mask = 0700

# By default, \\server\username shares can be connected to by anyone
# with access to the samba server.
# The following parameter makes sure that only "username" can connect
# to \\server\username
# This might need tweaking when using external authentication schemes
valid users = %S

# Un-comment the following and create the netlogon directory for Domain Logons
# (you need to configure Samba to act as a domain controller too.)
;[netlogon]
; comment = Network Logon Service
; path = /home/samba/netlogon
; guest ok = yes
; read only = yes

# Un-comment the following and create the profiles directory to store
# users profiles (see the "logon path" option above)
# (you need to configure Samba to act as a domain controller too.)
# The path below should be writable by all users so that their
# profile directory may be created the first time they log on
;[profiles]
; comment = Users profiles
; path = /home/samba/profiles
; guest ok = no
; browseable = no
; create mask = 0600
; directory mask = 0700

[printers]
comment = All Printers
browseable = no
path = /var/spool/samba
printable = yes
guest ok = no
read only = yes
create mask = 0700

# Windows clients look for this share name as a source of downloadable
# printer drivers
[print$]
comment = Printer Drivers
path = /var/lib/samba/printers
browseable = yes
read only = yes
guest ok = no
# Uncomment to allow remote administration of Windows print drivers.
# You may need to replace 'lpadmin' with the name of the group your
# admin users are members of.
# Please note that you also need to set appropriate Unix permissions
# to the drivers directory for these users to have write rights in it
; write list = root, @lpadmin

# A sample share for sharing your CD-ROM with others.
;[cdrom]
; comment = Samba server's CD-ROM
; read only = yes
; locking = no
; path = /cdrom
; guest ok = yes

# The next two parameters show how to auto-mount a CD-ROM when the
# cdrom share is accesed. For this to work /etc/fstab must contain
# an entry like this:
#
# /dev/scd0 /cdrom iso9660 defaults,noauto,ro,user 0 0
#
# The CD-ROM gets unmounted automatically after the connection to the
#
# If you don't want to use auto-mounting/unmounting make sure the CD
# is mounted on /cdrom
#
; preexec = /bin/mount /cdrom
; postexec = /bin/umount /cdrom
[XML_DBiTX]
comment = XML_DBiTX
path = /opt/lampp/htdocs/itx_export/XML_DBiTX/
browsable = yes
read only = no
public = yes
create mask = 0777
guest ok = No
[SCH]
comment = SCH
path = /opt/lampp/htdocs/checkmorpheus/SCH/
browsable = yes
read only = no
public = yes
create mask = 0777
guest ok = No
[HTDOCS]
comment = HTDOCS
path = /opt/lampp/htdocs/
browsable = yes
read only = no
public = yes
create mask = 0777
guest ok = No
[provacondivisione]
comment = prova
path = /home/provacondivisione/
browsable = yes
read only = no
public = yes
create mask = 0777
guest ok = No




I've tried to set "server signing = mandatory" but it seems doesn't work.
Do you have any suggestion?
Thank you very much (sorry for my English).
Marco

Have you tried making the necessary adjustments via the Windows credential manager? I recall having to add some server specific credentials to access a particular NAS at my workplace, (otherwise it attempted to use the domain credentials). Apologies if I'm on the wrong track with this.

Could you please define 'local users', are these local to the Samba server or the Windows PC ?
I ask this because you have in your shares 'public = yes', closely followed by 'guest ok = No'. Are you aware that 'public' is a synonym for 'guest ok' ? Are you also aware that 'public = yes' would turn on guest access and then 'guest ok = no' would turn it off again ? I say 'would' because neither of them will have any effect because you do not have 'map to guest = bad user' in global.

1 members found this post helpful.

Hi RPenny, for 'local users' I mean users on samba server. Everything was working fine until we enabled "smb signing" on the clients.

Hi Ferrari, until now we do not use Windows Credential Manager to save the "samba" user credential, I will try it

Yes, let us know how you get on with this.

Do your 'local users' have the same username & password as the domain users and are they also Samba users (have you run 'smbpasswd -a $USERNAME' as root ?)

You do not have guest access set up correctly so you will not get guest access, even if your Windows clients allow this.

There is also the problem that (as I understand it) you will require GSSAPI to sign and I think you will need to join the domain to get that working.

1 members found this post helpful.

smb v2 was initially supported (experimental) in samba version 3.5.0, debian 6 was released with samba version 3.5.6 but smb v2 was not fully functional until samba version 3.6.0. What samba version is running on your debian 6 system?

It could be an authentication, a signing protocol mismatch or just debian 6 signing if it works at all may not be compatible with Windows 10. You might have to increase the samba log level to see what is happening.

I guess signing was available in smb v1 but I do not know how it differs from smb v2 but it is deprecated. What about trying to access the server from another PC that isn't joined to the domain.

Whilst that is all true, I suppose the real question is, why is the OP still using an old EOL version of Debian ??

1 members found this post helpful.

Good question! but I don't have an answer 🤷*♀️
It is an old server that nobody whant to upgrade

If you're the administrator, then YOU should have the answer. And the answer is: upgrade the server, period. Using old, EOL stuff is a recipe for problems, security and otherwise. Right now, you are in a PERFECT situation to upgrade...all you need is another machine. Load the latest version of Debian (or whatever) on it, and configure it. You can play with the Samba configuration all you want, since the original box is still working. Once you get the problems solved, swap the machines and move on.

Beyond that, post #7 by rpenny asked the question on whether or not you've set up local users with smbpasswd; have you?? And ferrari asked about adding the particular credentials to the Windows configuration...did you??

The fact you're having problems from a Windows change is a PERFECT example of why you don't want to be running an old OS and version of Samba.

Ok, let me explain: I'm a Windows System Administrator while the linux server is under the edge of another technical manager and his think is "if it ain't broke, don't fix it". But now that we applied some new security policy to the MS AD domain (like smb signing) he will have to rethink his think.
I'd like to thanks you all for the precious help.

Great; which brings us back to him needing to update the system. The ONLY thing you can do as a Windows admin is to look at the Windows credential manager settings. Past that, there's nothing. Windows has problems with a LOT of things, but in this case it's more than likely it's a security issue. And the 'fix' is to update the Linux/Samba server. That's company politics which we can't solve.

In this case, Windows is (correctly) not allowing old crypto/insecure connections.

1 members found this post helpful.

+1 to these comments.