Samba

Related articles

• Active Directory Integration
• Samba/Active Directory domain controller
• NFS

Samba is a re-implementation of the SMB networking protocol. It facilitates file and printer sharing among Linux and Windows systems as an alternative to NFS. This article provides instructions for users on how to setup Samba.

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.

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.

Usage

User Management

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's 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_conf, 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 a share

Note: To allow the usage of guests on public shares, one may need to append map to guest = Bad User in the [global] section of /etc/samba/smb.conf. A different guest account may be used instead of the default provided nobody.

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

Starting services

To provide basic file sharing through SMB start/enable smb.service and/or nmb.service services. See the smbd(8) and nmbd(8) man pages for details, as the nmb.service service may not always be required.

Note: In samba 4.8.0-1, the units were renamed from smbd.service and nmbd.service to smb.service and nmb.service.

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.

# # create directory:
# mkdir /var/lib/samba/usershares
# # create group:
# groupadd -r sambashare
# # change the owner of the directory to 'root' and the group to 'sambashare':
# chown root:sambashare /var/lib/samba/usershares
# # change the permissions of the 'usershares' directory so that users in the group 'sambashare' can read, write and execute files:
# 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, for example in Thunar, you can 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 smb encrypt parameter globally and/or by share. Possible values are off, enabled (default value), desired, or required:

/etc/samba/smb.conf

[global]
  smb encrypt = desired

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 append to the [global] section of /etc/samba/smb.conf.

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

server multi channel support = yes

Setting a deadtime is useful to stop a server's resources 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

The write cache allows Samba to batch client writes into a more efficient write size for RAID disks (i.e. writes may be tuned to be the RAID stripe size) and can improve performance on systems where the disk subsystem is a bottleneck but there is free memory for userspace programs:

write cache size = 262144

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 synchronously 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.

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:

• smbclient requires a /etc/samba/smb.conf file (see #Installation), which you can create as an empty file using the touch utility.
• After installing cifs-utils or smbclient, load the cifs kernel module or reboot to prevent mount fails.

List public shares

The following command lists public shares on a server:

$ smbclient -L hostname -U%

Alternatively, running smbtree will show a tree diagram of all the shares. This is not advisable on a network with a lot of computers, but can be helpful for diagnosing if you have the correct sharename.

$ smbtree -b -N

Where the options are -b (--broadcast) to use broadcast instead of using the master browser and -N (-no-pass) to not ask for a password.

NetBIOS/WINS host names

You may need to start winbind.service in order to resolve host names with e.g., mount.cifs

If you are using apparmor and are unable to start winbind, you may need to add the below two lines to the apparmor profile for winbind:

/etc/apparmor.d/usr.sbin.winbindd

...
  /var/cache/samba/msg.lock/* rwk, 
  /run/winbindd.pid rwk,
  ...
}

The smbclient package provides a driver to resolve host names using WINS. To enable it, add wins to the “hosts” line in /etc/nsswitch.conf.

If it is not already there, add it to look roughly like this:

/etc/nsswitch.conf

...
 hosts: files mymachines myhostname mdns_minimal [NOTFOUND=return] resolve [!UNAVAIL=return] dns wins
 ...

You can test WINS resolution with nmblookup. 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) for more information.
• 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".
• To mount a Windows share without authentification, 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

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.

As mount entry

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

/etc/fstab

//SERVER/sharename /mnt/mountpoint cifs _netdev,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.

Tip: Use x-systemd.automount if you want them to be mounted only upon access. See Fstab#Remote filesystem 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 and Wants. 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.

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

automount

To automatically mount a share, 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 has the ability to browse Samba shares built in. To use a GUI in the KDE System Settings, you will need to install the kdenetwork-filesharing package.

If you get a "Time Out" Error when navigating with Dolphin, you should uncomment and edit the following line in smb.conf:

name resolve order = lmhosts bcast host wins

as shown in this page.

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.

• pyneighborhood is available in the official repositories.
• 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, the following methods allow one to manually probe for Samba shares.

1. First, install the nmap and smbclient packages.

2. nmap checks which ports are open:

# nmap -p 139 -sT "192.168.1.*"

In this case, a scan on the 192.168.1.* IP address range and port 139 has been performed, resulting in:

$ nmap -sT "192.168.1.*"

Starting nmap 3.78 ( http://www.insecure.org/nmap/ ) at 2005-02-15 11:45 PHT
Interesting ports on 192.168.1.1:
(The 1661 ports scanned but not shown below are in state: closed)
PORT     STATE SERVICE
139/tcp  open  netbios-ssn
5000/tcp open  UPnP

Interesting ports on 192.168.1.5:
(The 1662 ports scanned but not shown below are in state: closed)
PORT     STATE SERVICE
6000/tcp open  X11

Nmap run completed -- 256 IP addresses (2 hosts up) scanned in 7.255 seconds

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

3. Now that systems with port 139 open are revealed, use nmblookup(1) to check for NetBIOS names:

$ 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.

4. Use smbclient to list which services are shared on PUTER. If prompted for a password, pressing enter should still display the list:

$ smbclient -L \\PUTER

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 AppArmor

If using a share path located outside of a home-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

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

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.

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 NTFS_STATUS_ACCESS_DENIED error displayed, probably there is something to be solved at directory permission level.

Run the following commands as root to set correct permissions for folders:

# cd /home
# chmod -R 755 /home/yourUser/Shared

Access shared folder again as guest to be sure guest read access error has been solved.

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

See also

• Official website
• Samba: An Introduction
• Samba 3.2.x HOWTO and Reference Guide (outdated but still most extensive documentation)
• Wikipedia
• Gentoo:Samba/Guide
• Debian:SambaServerSimple