Samba

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Samba is the standard Windows interoperability suite of programs for Linux and Unix. Since 1992, Samba has provided secure, stable and fast file and print services for all clients using the SMB/CIFS protocol, such as all versions of DOS and Windows, OS/2, Linux and many others.

To share files through Samba, see #Server section; to access files shared through Samba on other machines, please see #Client section.

Server

Installation

Install the samba package.

Samba is configured in the /etc/samba/smb.conf configuration file, which is extensively documented in smb.conf(5).

Because the samba package does not provide this file, one needs to create it before starting smb.service.

A documented example as in smb.conf.default from the Samba git repository may be used to setup /etc/samba/smb.conf.

Note:
  • The default configuration sets log file to a non-writable location, which will cause errors - apply one of the following workarounds:
    • Change the log file location to a writable path: log file = /var/log/samba/%m.log
    • Change logging to a non-file backend solution: logging = syslog with syslog only = yes, or use logging = systemd
  • If required; the workgroup specified in the [global] section has to match the Windows workgroup (default WORKGROUP).
Tip: Whenever you modify the smb.conf file, run the testparm(1) command to check for syntactic errors.

Enabling and starting services

To provide basic file sharing through SMB, enable/start smb.service. See smbd(8) for details.

If you want to make your server accessible via NetBIOS host name, set the desired name in the netbios name option in smb.conf and enable/start nmb.service. See nmbd(8) for details.

Note: nmb.service is not required. However, it is needed to access Samba servers by hostname (e.g. smb://hostname/) for some hosts. If your network is only composed of machines running Windows 10 or later, consider installing a WSD daemon as well for your server to appear in the "Network" view.

Configure firewall

If you are using a firewall, do not forget to open required ports (usually 137-139 + 445). For a complete list, see Samba port usage.

UFW Rule

A Ufw App Profile for SMB/CIFS is included by default with the default installation of UFW in ufw-fileserver.

Allow Samba by running ufw allow CIFS as root.

If you deleted the profile, create/edit /etc/ufw/applications.d/samba and add the following content: 

[Samba]
title=LanManager-like file and printer server for Unix
description=The Samba software suite is a collection of programs that implements the SMB/CIFS protocol for unix systems, allowing you to serve files and printers to Windows, NT, OS/2 and DOS clients. This protocol is sometimes also referred to as the LanManager or NetBIOS protocol.
ports=137,138/udp|139,445/tcp

Then load the profile into UFW run ufw app update Samba as root.

Then finally, allow Samba by running ufw allow Samba as root.

firewalld service

To configure firewalld to allow Samba in the home zone, run: 

# firewall-cmd --permanent --add-service={samba,samba-client,samba-dc} --zone=home

The three service listed are:

--permanent ensures the changes remain after firewalld.service is restarted.

Usage

User management

The following section describes creating a local (tdbsam) database of Samba users. For user authentication and other purposes, Samba can also be bound to an Active Directory domain, can itself serve as an Active Directory domain controller, or can be used with an LDAP server.

Adding a user

Samba requires a Linux user account - you may use an existing user account or create a new one.

Note: The user/user group nobody should already exist on the system, it is used as the default guest account and may be used for shares containing guest ok = yes, thus preventing the need of user login on that share.

Although the user name is shared with Linux system, Samba uses a password separate from that of the Linux user accounts. Replace samba_user with the chosen Samba user account: 

# smbpasswd -a samba_user

Depending on the server role, existing File permissions and attributes may need to be altered for the Samba user account.

If you want the new user only to be allowed to remotely access the file server shares through Samba, you can restrict other login options：

  • disabling shell - usermod --shell /usr/bin/nologin --lock samba_user
  • disabling SSH logons - edit /etc/ssh/sshd_config, change option AllowUsers

Also see Security for hardening your system.

Listing users

Samba users can be listed using the pdbedit(8) command: 

# pdbedit -L -v
Changing user password

To change a user password, use smbpasswd: 

# smbpasswd samba_user

Creating an anonymous share

1. Create a Linux user which anonymous Samba users will be mapped to. 

# useradd guest -s /bin/nologin
Note: The username can be any valid Linux username, not just "guest". This user does not need to be a Samba user.

2. Add the following to /etc/samba/smb.conf: 

/etc/samba/smb.conf
...
[global]
security = user
map to guest = bad user
guest account = guest

[guest]
    comment = guest
    path = /tmp/
    public = yes
    only guest = yes
    writable = yes
    printable = no

Any anonymous users will now be mapped to the Linux user guest and have the ability to access any directories defined in guest.path, for example, /tmp/ in the configuration above.

Make sure shares have been properly defined as per the Share Definitions section of smb.conf.default.

Enable symlink following

Warning: Enabling the follow symlinks option can be a security risk.
/etc/samba/smb.conf
...
[global]
   follow symlinks = yes
   wide links = yes
   unix extensions = no

Then, restart smb.service.

Note: When using AppArmor, if the symlink points to a directory outside the user's home or the usershare directory, then you need to modify the AppArmor profile permissions.

Advanced Configuration

Enable Usershares

Note: This is an optional feature. Skip this section if you do not need it.

Usershares is a feature that gives non-root users the capability to add, modify, and delete their own share definitions.

  1. Create a directory for usershares: 
    # mkdir /var/lib/samba/usershares
  2. Create a user group: 
    # groupadd -r sambashare
  3. Change the owner of the directory to root and the group to sambashare: 
    # chown root:sambashare /var/lib/samba/usershares
  4. Change the permissions of the usershares directory so that users in the group sambashare can create files. This command also sets sticky bit, which is important to prevent users from deleting usershares of other users: 
    # chmod 1770 /var/lib/samba/usershares

Set the following parameters in the smb.conf configuration file: 

/etc/samba/smb.conf
[global]
  usershare path = /var/lib/samba/usershares
  usershare max shares = 100
  usershare allow guests = yes
  usershare owner only = yes

Add the user to the sambashare group. Replace your_username with the name of your user: 

# gpasswd sambashare -a your_username

Restart smb.service and nmb.service services.

Log out and log back in.

If you want to share paths inside your home directory you must make it accessible for the group others.

In the GUI, you can use Thunar or Dolphin - right click on any directory and share it on the network.

In the CLI, use one of the following commands, replacing italic sharename, user, ... : 

# net usershare add sharename abspath [comment] [user:{R|D|F}] [guest_ok={y|n}]
# net usershare delete sharename
# net usershare list wildcard-sharename
# net usershare info wildcard-sharename

Set and forcing permissions

Permissions may be applied to both the server and shares: 

/etc/samba/smb.conf
[global]
  ;inherit owner = unix only ; Inherit ownership of the parent directory for new files and directories
  ;inherit permissions = yes ; Inherit permissions of the parent directory for new files and directories
  create mask = 0664
  directory mask = 2755
  force create mode = 0644
  force directory mode = 2755
  ...

[media]
  comment = Media share accessible by greg and pcusers
  path = /path/to/media
  valid users = greg @pcusers
  force group = +pcusers
  public = no
  writable = yes
  create mask = 0664
  directory mask = 2775
  force create mode = 0664
  force directory mode = 2775

[public]
  comment = Public share where archie has write access
  path = /path/to/public
  public = yes
  read only = yes
  write list = archie
  printable = no

[guests]
  comment = Allow all users to read/write
  path = /path/to/guests
  public = yes
  only guest = yes
  writable = yes
  printable = no

See smb.conf(5) for a full overview of possible permission flags and settings.

Restrict protocols for better security

Warning: By default, Samba versions prior to 4.11 allow connections using the outdated and insecure SMB1 protocol. When using one these Samba versions, it is highly recommended to set server min protocol = SMB2_02 to protect yourself from ransomware attacks. In Samba 4.11 and newer, SMB2 is the default min protocol, so no changes are required there.

Append server min protocol and server max protocol in /etc/samba/smb.conf to force usage of a minimum and maximum protocol: 

/etc/samba/smb.conf
[global]
  server min protocol = SMB2_02
  ; server max protocol = SMB3

See server max protocol in smb.conf(5) for an overview of supported protocols.

For compatibility with older clients and/or servers, you might need to set client min protocol = CORE or server min protocol = CORE, but please note that this makes you vulnerable to exploits in SMB1 including ransomware attacks.

Tip: Use server min protocol = SMB3_00 when clients should only connect using the latest SMB3 protocol, e.g. on clients running Windows 8 and later.

Clients using mount.cifs may need to specify the correct vers=*, e.g.: 

# mount -t cifs //SERVER/sharename /mnt/mountpoint -o username=username,password=password,iocharset=utf8,vers=3.1.1

See mount.cifs(8) for more information.

Use native SMB transport encryption

Native SMB transport encryption is available in SMB version 3.0 or newer. Clients supporting this type of encryption include Windows 8 and newer, Windows server 2012 and newer, and smbclient of Samba 4.1 and newer.

To use native SMB transport encryption by default, set the server smb encrypt parameter globally and/or by share. Possible values are off, enabled (default value), desired, or required: 

/etc/samba/smb.conf
[global]
  server smb encrypt = desired

To configure encryption for on the client side, use the option client smb encrypt.

See smb.conf(5) for more information, especially the paragraphs Effects for SMB1 and Effects for SMB2.

Tip: When mounting a share, specify the seal mount option to force usage of encryption.

Disable printer sharing

By default Samba shares printers configured using CUPS.

If you do not want printers to be shared, use the following settings: 

/etc/samba/smb.conf
[global]
  load printers = no
  printing = bsd
  printcap name = /dev/null
  disable spoolss = yes
  show add printer wizard = no

Block certain file extensions on Samba share

Note: Setting this parameter will affect the performance of Samba, as it will be forced to check all files and directories for a match as they are scanned.

Samba offers an option to block files with certain patterns, like file extensions. This option can be used to prevent dissemination of viruses or to dissuade users from wasting space with certain files. More information about this option can be found in smb.conf(5). 

/etc/samba/smb.conf
...
[myshare]
  comment = Private
  path = /mnt/data
  read only = no
  veto files = /*.exe/*.com/*.dll/*.bat/*.vbs/*.tmp/*.mp3/*.avi/*.mp4/*.wmv/*.wma/

Improve throughput

Warning: Beware this may lead to corruption/connection issues and potentially cripple your TCP/IP stack.

The default settings should be sufficient for most users. However setting the 'socket options' correct can improve performance, but getting them wrong can degrade it by just as much. Test the effect before making any large changes.

Read the smb.conf(5) man page before applying any of the options listed below.

The following settings should be appended to the [global] section of /etc/samba/smb.conf.

SMB3 multi-channel may improve performance, however it may result in data corruption under some rare conditions. Future releases may improve this situation: 

server multi channel support = yes

Setting a deadtime is useful to stop a server's resources from being exhausted by a large number of inactive connections: 

deadtime = 30

The usage of sendfile may make more efficient use of the system CPU's and cause Samba to be faster: 

use sendfile = yes

Setting min receivefile size allows zero-copy writes directly from network socket buffers into the filesystem buffer cache (if available). It may improve performance but user testing is recommended: 

min receivefile size = 16384

Reading/writing files asynchronously may improve performance instead of using synchronous writes: 

aio read size = 1
aio write size = 1

Increasing the receive/send buffers size and socket optimize flags might be useful to improve throughput. It is recommended to test each flag separately as it may cause issues on some networks: 

socket options = IPTOS_LOWDELAY TCP_NODELAY IPTOS_THROUGHPUT SO_RCVBUF=131072 SO_SNDBUF=131072
Note: Network-interface adjustments may be needed for some options to work, see Sysctl#Networking.

Enable access for old clients/devices

Latest versions of Samba no longer offer older authentication methods and protocols which are still used by some older clients (IP cameras, etc). These devices usually require Samba server to allow NTMLv1 authentication and NT1 version of the protocol, known as CIFS. For these devices to work with latest Samba, you need to add these two configuration parameters into [global] section: 

server min protocol = NT1
ntlm auth = yes

Anonymous/guest access to a share requires just the first parameter. If the old device will access with username and password, you also need the add the second line too.

Enable Spotlight searching

Spotlight allows supporting clients (e.g. MacOS Finder) to quickly search shared files.

Install and start/enable OpenSearch. Install fs2es-indexerAUR, configure the directories you want to index in /etc/fs2es-indexer/config.yml, and start/enable fs2es-indexer.service for periodic indexing.

Edit smb.conf as described in the Samba wiki to enable Spotlight per share, and restart smb.service to apply the changes.

Client

Install smbclient for an ftp-like command line interface. See smbclient(1) for commonly used commands.

For a lightweight alternative (without support for listing public shares, etc.), install cifs-utils that provides /usr/bin/mount.cifs.

Depending on the desktop environment, GUI methods may be available. See #File manager configuration for use with a file manager.

Note:

List public shares

The following command lists public shares on a server: 

$ smbclient -L hostname -U%

Alternatively, running $ smbtree -N will show a tree diagram of all the shares. It uses broadcast queries and is therefore not advisable on a network with a lot of computers, but can be helpful for diagnosing if you have the correct sharename. The -N (-no-pass) option suppresses the password prompt.

Note: smbtree uses SMB1 and NetBIOS, which means they must be enabled on the servers and you need to set client min protocol = NT1 in smb.conf on the client. Otherwise, smbtree will show empty output.

NetBIOS/WINS host names

Samba clients handle NetBIOS host names automatically by default (the behavior is controlled by the name resolve order option in smb.conf). Other programs (including mount.cifs) typically use Name Service Switch, which does not handle NetBIOS by default.

The smbclient package provides a libnss driver to resolve NetBIOS host names. To use it, install it along with the samba package (which provides the winbindd daemon), start/enable winbind.service and add wins to the hosts line in nsswitch.conf(5): 

/etc/nsswitch.conf
...
hosts: mymachines resolve [!UNAVAIL=return] files myhostname dns wins
...
Note: Due to a current mistake in winbind.service, you may have to modify the unit file as described in this bug-report

Now, during host resolving (e.g. when using mount.cifs or just ping netbios-name), winbindd will resolve the host name by sending queries using NetBIOS Name Service (NBNS, also known as WINS) protocol.

By default it sends a broadcast query to your local network. If you have a WINS server, you can add wins server = wins-server-ip to smb.conf and restart winbind.service, then winbindd and other Samba clients will send unicast queries to the specified IP.

If you want to resolve your local host name (specified in the netbios name option in smb.conf), start/enable nmb.service, which will handle incoming queries.

You can test WINS resolution with nmblookup. By default it sends broadcast queries to your local network regardless of the wins server option.

Note that WINS resolution requires incoming traffic originating from port 137.

Disable NetBIOS/WINS support

When not using NetBIOS/WINS host name resolution, it may be preferred to disable this protocol: 

/etc/samba/smb.conf
[global]
  disable netbios = yes
  dns proxy = no

Finally disable/stop winbind.service.

Manual mounting

Create a mount point for the share: 

# mkdir /mnt/mountpoint

Mount the share using mount.cifs as type. Not all the options listed below are needed or desirable: 

# mount -t cifs //SERVER/sharename /mnt/mountpoint -o username=username,password=password,workgroup=workgroup,iocharset=utf8,uid=username,gid=group

The options uid and gid corresponds to the local (e.g. client) user/user group to have read/write access on the given path.

Note:
  • If the uid and gid being used does not match the user of the server, the forceuid and forcegid options may be helpful. However note permissions assigned to a file when forceuid or forcegid are in effect may not reflect the the real (server) permissions. See the File And Directory Ownership And Permissions section in mount.cifs(8) § FILE AND DIRECTORY OWNERSHIP AND PERMISSIONS for more information.
  • To mount a Windows share without authentication, use "username=*".
Warning: Using uid and/or gid as mount options may cause I/O errors, it is recommended to set/check correct File permissions and attributes instead.
  • SERVER — The server name.
  • sharename — The shared directory.
  • mountpoint — The local directory where the share will be mounted.
  • [-o options] — See mount.cifs(8) for more information.
Note:
  • Abstain from using a trailing /. //SERVER/sharename/ will not work.
  • If your mount does not work stable, stutters or freezes, try to enable different SMB protocol version with vers= option. For example, vers=2.0 for Windows Vista mount.
  • If having timeouts on a mounted network share with cifs on a shutdown, see wpa_supplicant#Problem with mounted network shares (cifs) and shutdown.

Storing share passwords

Storing passwords in a world readable file is not recommended. A safer method is to use a credentials file instead, e.g. inside /etc/samba/credentials: 

/etc/samba/credentials/share
username=myuser
password=mypass

For the mount command replace username=myuser,password=mypass with credentials=/etc/samba/credentials/share.

The credential file should explicitly readable/writeable to root: 

# chown root:root /etc/samba/credentials
# chmod 700 /etc/samba/credentials
# chmod 600 /etc/samba/credentials/share

Automatic mounting

Note: You may need to enable systemd-networkd-wait-online.service or NetworkManager-wait-online.service (depending on your setup) to proper enable booting on start-up.

Using NetworkManager and GIO/gvfs

NetworkManager can be configured to run a script on network status change. This script uses the gio command so that it mounts the Samba shares automatically, the same way your file manager does, as explained below. The script also safely unmounts the Samba shares before the relevant network connection is disabled by listening for the pre-down and vpn-pre-down events. Make the script is executable after creating it. 

/etc/NetworkManager/dispatcher.d/30-samba.sh
#!/bin/sh

# Find the connection UUID with "nmcli con show" in terminal.
# All NetworkManager connection types are supported: wireless, VPN, wired...
WANTED_CON_UUID="CHANGE-ME-NOW-9c7eff15-010a-4b1c-a786-9b4efa218ba9"

# The user the share will be mounted under
USER="yourusername"
# The path that appears in your file manager when you manually mount the share you want
SMB_URL="smb://servername/share"

# Get runtime user directory. If it does not exist, do nothing and just exit
XDG_RUNTIME_DIR=$(loginctl show-user --property=RuntimePath --value "$USER") || exit 0

if [ "$CONNECTION_UUID" = "$WANTED_CON_UUID" ]; then
    
    # Script parameter $1: network interface name, not used
    # Script parameter $2: dispatched event
    
    case "$2" in
        "up")
            su $USER -c "DBUS_SESSION_BUS_ADDRESS=unix:path=$XDG_RUNTIME_DIR/bus gio mount $SMB_URL"
            ;;
        "pre-down"|"vpn-pre-down")
            su $USER -c "DBUS_SESSION_BUS_ADDRESS=unix:path=$XDG_RUNTIME_DIR/bus gio mount -uf $SMB_URL"
            ;;
    esac
fi

Create a symlink inside /etc/NetworkManager/dispatcher.d/pre-down to catch the pre-down events: 

# ln -s /etc/NetworkManager/dispatcher.d/30-samba.sh /etc/NetworkManager/dispatcher.d/pre-down.d/30-samba.sh
Note: Since this script uses the user bus, it will only work if the user has active sessions. This means that the share will not mount automatically after boot if the connection is established before you are logged in.

As mount entry

This is a simple example of a cifs mount entry that requires authentication: 

/etc/fstab
//SERVER/sharename /mnt/mountpoint cifs _netdev,nofail,username=myuser,password=mypass 0 0
Note:
  • Spaces in sharename should be replaced by \040 (ASCII code for space in octal). For example, //SERVER/share name on the command line should be //SERVER/share\040name in /etc/fstab.
  • To allow users to mount it as long as the mount point resides in a directory controllable by the user; i.e. the user's home, append the users mount option. The option is users (plural). For other filesystem types handled by mount, this option is usually user; sans the "s".
Tip: Use x-systemd.automount if you want them to be mounted only upon access. See Fstab#Remote file system for details.

As systemd unit

Create a new .mount file inside /etc/systemd/system, e.g. mnt-myshare.mount. See systemd.mount(5) for details.

Note: Make sure the filename corresponds to the mountpoint you want to use. E.g. the unit name mnt-myshare.mount can only be used if are going to mount the share under /mnt/myshare. Otherwise the following error might occur: systemd[1]: mnt-myshare.mount: Where= setting does not match unit name. Refusing..

What= path to share

Where= path to mount the share

Options= share mounting options

Note:
  • Network mount units automatically acquire After dependencies on remote-fs-pre.target, network.target and network-online.target, and gain a Before dependency on remote-fs.target unless nofail mount option is set. Towards the latter a Wants unit is added as well.
  • Append noauto to Options preventing automatically mount during boot (unless it is pulled in by some other unit).
  • If you want to use a hostname for the server you want to share (instead of an IP address), add nss-lookup.target to After. This might avoid mount errors at boot time that do not arise when testing the unit.
/etc/systemd/system/mnt-myshare.mount
[Unit]
Description=Mount Share at boot

[Mount]
What=//server/share
Where=/mnt/myshare
Options=_netdev,credentials=/etc/samba/credentials/myshare,iocharset=utf8,rw
Type=cifs
TimeoutSec=30

[Install]
WantedBy=multi-user.target
Tip:
  • In case of an unreachable system, append ForceUnmount=true to [Mount], allowing the share to be (force-)unmounted.
  • If your share has groups with read-only access, append uid=username or gid=group to Options=, to specify your user / group allowing writing to the share.

To use mnt-myshare.mount, start the unit and enable it to run on system boot.

automount

To automatically mount a share (when accessed, like autofs), one may use the following automount unit: 

/etc/systemd/system/mnt-myshare.automount
[Unit]
Description=Automount myshare

[Automount]
Where=/mnt/myshare

[Install]
WantedBy=multi-user.target

Disable/stop the mnt-myshare.mount unit, and enable/start mnt-myshare.automount to automount the share when the mount path is being accessed.

Tip: Append TimeoutIdleSec to enable auto unmount. See systemd.automount(5) for details.

smbnetfs

Note: smbnetfs needs an intact Samba server setup. See above on how to do that.

First, check if you can see all the shares you are interested in mounting: 

$ smbtree -U remote_user

If that does not work, find and modify the following line in /etc/samba/smb.conf accordingly: 

domain master = auto

Now restart smb.service and nmb.service.

If everything works as expected, install smbnetfs from the official repositories.

Then, add the following line to /etc/fuse.conf: 

user_allow_other

Now copy the directory /etc/smbnetfs/.smb to your home directory: 

$ cp -a /etc/smbnetfs/.smb ~

Then create a link to smb.conf: 

$ ln -sf /etc/samba/smb.conf ~/.smb/smb.conf

If a username and a password are required to access some of the shared folders, edit ~/.smb/smbnetfs.auth to include one or more entries like this: 

~/.smb/smbnetfs.auth
auth			"hostname" "username" "password"

It is also possible to add entries for specific hosts to be mounted by smbnetfs, if necessary. More details can be found in ~/.smb/smbnetfs.conf.

If you are using the Dolphin or GNOME Files, you may want to add the following to ~/.smb/smbnetfs.conf to avoid "Disk full" errors as smbnetfs by default will report 0 bytes of free space: 

~/.smb/smbnetfs.conf
free_space_size 1073741824

When you are done with the configuration, you need to run 

$ chmod 600 ~/.smb/smbnetfs.*

Otherwise, smbnetfs complains about 'insecure config file permissions'.

Finally, to mount your Samba network neighbourhood to a directory of your choice, call 

$ smbnetfs mount_point
Daemon

The Arch Linux package also maintains an additional system-wide operation mode for smbnetfs. To enable it, you need to make the said modifications in the directory /etc/smbnetfs/.smb.

Then, you can start and/or enable the smbnetfs daemon as usual. The system-wide mount point is at /mnt/smbnet/.

autofs

See Autofs for information on the kernel-based automounter for Linux.

File manager configuration

GNOME Files, Nemo, Caja, Thunar and PCManFM

In order to access samba shares through GNOME Files, Nemo, Caja, Thunar or PCManFM, install the gvfs-smb package, available in the official repositories.

Press Ctrl+l and enter smb://servername/share in the location bar to access your share.

The mounted share is likely to be present at /run/user/your_UID/gvfs or ~/.gvfs in the filesystem.

KDE

KDE applications (like Dolphin) has the ability to browse Samba shares built in. Use the path smb://servername/share to browse the files. If you want to access files from on non-KDE application, you can install kio-fuse.

To use a GUI in the KDE System Settings, you will need to install the kdenetwork-filesharing package.

Other graphical environments

There are a number of useful programs, but they may need to have packages created for them. This can be done with the Arch package build system. The good thing about these others is that they do not require a particular environment to be installed to support them, and so they bring along less baggage.

  • pyneighborhoodAUR is available in the AUR.
  • LinNeighborhood, RUmba, xffm-samba plugin for Xffm are not available in the official repositories or the AUR. As they are not officially (or even unofficially supported), they may be obsolete and may not work at all.

Tips and tricks

Discovering network shares

If nothing is known about other systems on the local network, and automated tools such as smbnetfs are not available, you can manually probe for Samba shares.

First, install the nmap and smbclient packages.

Use nmap to scan your local network to find systems with TCP port 445 open, which is the port used by the SMB protocol. Note that you may need to use -Pn or set a custom ping scan type (e.g. -PS445) because Windows systems are usually firewalled. 

$ nmap -p 445 "192.168.1.*"
Starting Nmap 7.92 ( https://nmap.org ) at 2022-03-13 12:00 UTC
Nmap scan report for 192.168.1.1
Host is up (0.0011s latency).

PORT    STATE  SERVICE
445/tcp open  microsoft-ds

Nmap scan report for 192.168.1.2
Host is up (0.00011s latency).

PORT    STATE SERVICE
445/tcp open  microsoft-ds

Nmap done: 256 IP addresses (2 hosts up) scanned in 2.45 seconds

The first result is another system; the second happens to be the client from where this scan was performed.

Now you can connect to there IP addresses directly, but if you want to use NetBIOS host names, you can use nmblookup(1) to check for NetBIOS names. Note that this will not work if NetBIOS is disabled on the server. 

$ nmblookup -A 192.168.1.1
Looking up status of 192.168.1.1
        PUTER           <00> -         B <ACTIVE>
        HOMENET         <00> - <GROUP> B <ACTIVE>
        PUTER           <03> -         B <ACTIVE>
        PUTER           <20> -         B <ACTIVE>
        HOMENET         <1e> - <GROUP> B <ACTIVE>
        USERNAME        <03> -         B <ACTIVE>
        HOMENET         <1d> -         B <ACTIVE>
        MSBROWSE        <01> - <GROUP> B <ACTIVE>

Regardless of the output, look for <20>, which shows the host with open services.

Use smbclient(1) to list which services are shared on these systems. You can use NetBIOS host name (PUTER in this example) instead of IP when available. If prompted for a password, pressing enter should still display the list: 

$ smbclient -L \\192.168.1.1
Sharename       Type      Comment
---------       ----      -------
MY_MUSIC        Disk
SHAREDDOCS      Disk
PRINTER$        Disk
PRINTER         Printer
IPC$            IPC       Remote Inter Process Communication

Server               Comment
---------            -------
PUTER

Workgroup            Master
---------            -------
HOMENET               PUTER

Remote control of Windows computer

Samba offers a set of tools for communication with Windows. These can be handy if access to a Windows computer through remote desktop is not an option, as shown by some examples.

Send shutdown command with a comment: 

$ net rpc shutdown -C "comment" -I IPADDRESS -U USERNAME%PASSWORD

A forced shutdown instead can be invoked by changing -C with comment to a single -f. For a restart, only add -r, followed by a -C or -f.

Stop and start services: 

$ net rpc service stop SERVICENAME -I IPADDRESS -U USERNAME%PASSWORD

To see all possible net rpc command: 

$ net rpc

Troubleshooting

Failed to start Samba SMB/CIFS server

Possible solutions:

  • Check smb.conf on syntactic errors with testparm(1).
  • Set correct permissions for /var/cache/samba/ and restart smb.service:
# chmod 0755 /var/cache/samba/msg

Permission issues on SELinux

SELinux not allow samba to access user home directories by default, to solve this, run: 

# setsebool -P samba_enable_home_dirs 1

Similarly, samba_export_all_ro and samba_export_all_rw make Samba has the ability to read or "read and write" all files.

Permission issues on AppArmor

If using a share path located outside of a home or usershares directory, whitelist it in /etc/apparmor.d/local/usr.sbin.smbd. E.g.: 

/etc/apparmor.d/local/usr.sbin.smbd
"/data/" rk,
"/data/**" lrwk,

No dialect specified on mount

The client is using an unsupported SMB/CIFS version that is required by the server.

See #Restrict protocols for better security for more information.

Unable to overwrite files, permissions errors

Tango-inaccurate.pngThe factual accuracy of this article or section is disputed.Tango-inaccurate.png

Reason: An user should set/check for server/client permissions, instead of using incorrect/possible insecure flags. (Discuss in Talk:Samba)

Possible solutions:

  • Append the mount option nodfs to the /etc/fstab entry.
  • Add msdfs root = no to the [global] section of the server's /etc/samba/smb.conf.

Windows clients keep asking for password even if Samba shares are created with guest permissions

Set map to guest inside the global section of /etc/samba/smb.conf: 

map to guest = Bad User

From Samba 4.10.10 you should use Bad Password instead Bad User.

Windows 7 connectivity problems - mount error(12): cannot allocate memory

A known Windows 7 bug that causes "mount error(12): cannot allocate memory" on an otherwise perfect cifs share on the Linux end can be fixed by setting a few registry keys on the Windows box as follows:

  • HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\LargeSystemCache (set to 1)
  • HKLM\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters\Size (set to 3)

Alternatively, start Command Prompt in Admin Mode and execute the following: 

reg add "HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management" /v "LargeSystemCache" /t REG_DWORD /d 1 /f
reg add "HKLM\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters" /v "Size" /t REG_DWORD /d 3 /f

Do one of the following for the settings to take effect:

  • Restart Windows
  • Restart the Server service via services.msc
  • From the Command Prompt run: 'net stop lanmanserver' and 'net start lanmanserver' - The server may automatically restart after stopping it.
Note: Googling will reveal another tweak recommending users to add a key modifying the "IRPStackSize" size. This is incorrect for fixing this issue under Windows 7. Do not attempt it.

Original article.

Windows 10 1709 and up connectivity problems - "Windows cannot access" 0x80004005

This error affects some machines running Windows 10 version 1709 and later. It is not related to SMB1 being disabled in this version but to the fact that Microsoft disabled insecure logons for guests on this version for some, but not others.

To fix, open Group Policy Editor (gpedit.msc). Navigate to Computer configuration\administrative templates\network\Lanman Workstation > Enable insecure guest logons and enable it. Alternatively,change the following value in the registry: 

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters]
"AllowInsecureGuestAuth"=dword:1

Error: Failed to retrieve printer list: NT_STATUS_UNSUCCESSFUL

If you are a home user and using samba purely for file sharing from a server or NAS, you are probably not interested in sharing printers through it. If so, you can prevent this error from occurring by adding the following lines to your /etc/samba/smb.conf: 

/etc/samba/smb.conf
[global]
  load printers = No
  printing = bsd
  printcap name = /dev/null
  disable spoolss = Yes

Restart the samba service, smb.service, and then check your logs: 

# cat /var/log/samba/smbd.log

and the error should now no longer be appearing.

Sharing a folder fails

It means that while you are sharing a folder from Dolphin (file manager) and everything seems ok at first, after restarting Dolphin the share icon is gone from the shared folder, and also some output like this in terminal (Konsole) output: 

‘net usershare’ returned error 255: net usershare: usershares are currently disabled

To fix it, enable usershare as described in #Enable Usershares.

"Browsing" network fails with "Failed to retrieve share list from server"

And you are using a firewall (iptables) because you do not trust your local (school, university, hotel) network. This may be due to the following: When the smbclient is browsing the local network it sends out a broadcast request on udp port 137. The servers on the network then reply to your client but as the source address of this reply is different from the destination address iptables saw when sending the request for the listing out, iptables will not recognize the reply as being "ESTABLISHED" or "RELATED", and hence the packet is dropped. A possible solution is to add: 

iptables -t raw -A OUTPUT -p udp -m udp --dport 137 -j CT --helper netbios-ns

to your iptables setup.

For Uncomplicated Firewall, you need to add nf_conntrack_netbios_ns to the end of the following line in /etc/default/ufw 

IPT_MODULES="nf_conntrack_ftp nf_nat_ftp nf_conntrack_irc nf_nat_irc"

and then run the following commands as root: 

echo 1 > /proc/sys/net/netfilter/nf_conntrack_helper
ufw allow CIFS
ufw reload

To make this change persistent across reboots, add the following line at the end of /etc/ufw/sysctl.conf: 

net.netfilter.nf_conntrack_helper=1

Protocol negotiation failed: NT_STATUS_INVALID_NETWORK_RESPONSE

The client probably does not have access to shares. Make sure clients' IP address is in hosts allow = line in /etc/samba/smb.conf.

Another problem could be, that the client uses an invalid protocol version. To check this try to connect with the smbclient where you specify the maximum protocol version manually: 

$ smbclient -U <user name> -L //<server name> -m <protocol version: e. g. SMB2> -W <domain name>

If the command was successful then create a configuration file: 

~/.smb/smb.conf
[global]
  workgroup = <domain name>
  client max protocol = SMB2

Connection to SERVER failed: (Error NT_STATUS_UNSUCCESSFUL)

You are probably passing a wrong server name to smbclient. To find out the server name, run hostnamectl on the server and look at "Transient hostname" line

Connection to SERVER failed: (Error NT_STATUS_CONNECTION_REFUSED)

Make sure that the server has started. The shared directories should exist and be accessible.

Protocol negotiation failed: NT_STATUS_CONNECTION_RESET

Probably the server is configured not to accept protocol SMB1. Add option client max protocol = SMB2 in /etc/samba/smb.conf. Or just pass argument -m SMB2 to smbclient.

Password Error when correct credentials are given (error 1326)

Samba 4.5 has NTLMv1 authentication disabled by default. It is recommend to install the latest available upgrades on clients and deny access for unsupported clients.

If you still need support for very old clients without NTLMv2 support (e.g. Windows XP), it is possible force enable NTLMv1, although this is not recommend for security reasons: 

/etc/samba/smb.conf
[global]
  lanman auth = yes
  ntlm auth = yes

If NTLMv2 clients are unable to authenticate when NTLMv1 has been enabled, create the following file on the client: 

/home/user/.smb/smb.conf
[global]
  sec = ntlmv2
  client ntlmv2 auth = yes

This change also affects samba shares mounted with mount.cifs. If after upgrade to Samba 4.5 your mount fails, add the sec=ntlmssp option to your mount command, e.g. 

mount.cifs //server/share /mnt/point -o sec=ntlmssp,...

See the mount.cifs(8) man page: ntlmssp - Use NTLMv2 password hashing encapsulated in Raw NTLMSSP message. The default in mainline kernel versions prior to v3.8 was sec=ntlm. In v3.8, the default was changed to sec=ntlmssp.

Mapping reserved Windows characters

Starting with kernel 3.18, the cifs module uses the "mapposix" option by default. When mounting a share using unix extensions and a default Samba configuration, files and directories containing one of the seven reserved Windows characters : \ * < > ? are listed but cannot be accessed.

Possible solutions are:

  • Use the undocumented nomapposix mount option for cifs
# mount.cifs //server/share /mnt/point -o nomapposix
  • Configure Samba to remap mapposix ("SFM", Services for Mac) style characters to the correct native ones using fruit 
/etc/samba/smb.conf
[global]
  vfs objects = catia fruit
  fruit:encoding = native
  • Manually remap forbidden characters using catia 
/etc/samba/smb.conf
[global]
  vfs objects = catia
  catia:mappings = 0x22:0xf022, 0x2a:0xf02a, 0x2f:0xf02f, 0x3a:0xf03a, 0x3c:0xf03c, 0x3e:0xf03e, 0x3f:0xf03f, 0x5c:0xf05c, 0x7c:0xf07c, 0x20:0xf020

The latter approach (using catia or fruit) has the drawback of filtering files with unprintable characters.

Folder shared inside graphical environment is not available to guests

This section presupposes:

  1. Usershares are configured following previous section
  2. A shared folder has been created as a non-root user from GUI
  3. Guests access has been set to shared folder during creation
  4. Samba service has been restarted at least once since last /etc/samba/smb.conf file modification

For clarification purpose only, in the following sub-sections is assumed:

  • Shared folder is located inside user home directory path (/home/yourUser/Shared)
  • Shared folder name is MySharedFiles
  • Guest access is read-only.
  • Windows users will access shared folder content without login prompt

Verify correct samba configuration

Run the following command from a terminal to test configuration file correctness: 

$ testparm

Verify correct shared folder creation

Run the following commands from a terminal: 

$ cd /var/lib/samba/usershare
$ ls

If everything is fine, you will notice a file named mysharedfiles

Read the file contents using the following command: 

$ cat mysharedfiles

The terminal output should display something like this: 

/var/lib/samba/usershare/mysharedfiles
path=/home/yourUser/Shared
comment=
usershare_acl=S-1-1-0:r
guest_ok=y
sharename=MySharedFiles

Verify folder access by guest

Run the following command from a terminal. If prompted for a password, just press Enter: 

$ smbclient -L localhost

If everything is fine, MySharedFiles should be displayed under Sharename column

Run the following command in order to access the shared folder as guest (anonymous login) 

$ smbclient -N //localhost/MySharedFiles

If everything is fine samba client prompt will be displayed: 

smb: \>

From samba prompt verify guest can list directory contents: 

smb: \> ls

If the NTFS_STATUS_ACCESS_DENIED error is displayed, the issue is likely to be with Unix directory permissions. Ensure that your samba user has access to the folder and all parent folders. You can test this by sudoing to the user and attempting to list the mount directory, and all of its parents.

Mount error: Host is down

This error might be seen when mounting shares of Synology NAS servers. Use the mount option vers=1.0 to solve it.

Note: SMB version 1 is known to have security vulnerabilities and was used in successful ransomware attacks.

Software caused connection abort

File managers that utilizes gvfs-smb can show the error Software caused connection abort when writing a file to a share/server. This may be due to the server running SMB/CIFS version 1, which many routers use for USB drive sharing (e.g. Belkin routers). To write to these shares specify the CIFS version with the option vers=1.0. E.g.: 

/etc/fstab
//SERVER/sharename /mnt/mountpoint cifs _netdev,guest,file_mode=0777,dir_mode=0777,vers=1.0 0 0

This can also happen after updating Samba to version 4.11, which deactivates SMB1 as default, and accessing any Samba share. You can reenable it by adding 

/etc/samba/smb.conf
[global]
client min protocol = CORE

Connection problem (due to authentification error)

Be sure that you do not leave any space characters before your username in Samba client configuration file as follows: 

~/.samba
username= user
password=pass

The correct format is: 

~/.samba
username=user
password=pass

Windows 1709 or up does not discover the samba server in Network view

With Windows 10 version 1511, support for SMBv1 and thus NetBIOS device discovery was disabled by default. Depending on the actual edition, later versions of Windows starting from version 1709 ("Fall Creators Update") do not allow the installation of the SMBv1 client anymore. This causes hosts running Samba not to be listed in the Explorer's "Network (Neighborhood)" views. While there is no connectivity problem and Samba will still run fine, users might want to have their Samba hosts to be listed by Windows automatically. wsddAUR implements a Web Service Discovery host daemon. This enables (Samba) hosts, like your local NAS device, to be found by Web Service Discovery Clients like Windows. The default settings should work for most installations, all you need to do is start enable wsdd.service.

If the default configuration (advertise itself as the machine hostname in group "WORKGROUP") should be all you need in most cases. If you need, you can change configuration options by passing additional arguments to wsdd by adding them in /etc/conf.d/wsdd (see the manual page for wsdd for details).

wsdd2AUR does the same thing, but is written in C instead of Python. By default, it will look for the netbios name and workgroup values in smb.conf.

IOS Files can no longer copy-to Samba share on Arch Linux beginning with IOS 14.5

Beginning with IOS 14.5 attempting to transfer from a device running IOS using the "Files" app to a samba share on Arch Linux will result in the error: 

The operation couldn't be completed
Operation canceled

To correct this problem, add add the following to the global section of your smb.conf and restart smb.service. Comment optional: 

## addition for IOS Files transfer-to server
vfs object = fruit streams_xattr

See https://apple.stackexchange.com/q/424681 Apple.Stackexchange.com - "The operation couldn't be completed"/"Operation canceled" error message when saving to a Samba share via Files app.

See also