Samba: Difference between revisions

Revision as of 15:13, 11 April 2022

This guide will help you on how to use samba on nixos.

Samba Client

cifs mount

The following snippets shows how to mount a CIFS (Windows) share in NixOS. Replace all <FIELDS> with concrete values:

{
  fileSystems."/mnt/share" = {
      device = "//<IP_OR_HOST>/path/to/share";
      fsType = "cifs";
      options = let
        # this line prevents hanging on network split
        automount_opts = "x-systemd.automount,noauto,x-systemd.idle-timeout=60,x-systemd.device-timeout=5s,x-systemd.mount-timeout=5s";

      in ["${automount_opts},credentials=/etc/nixos/smb-secrets"];
  };
}

Also create /etc/nixos/smb-secrets with the following content (domain= can be optional)

username=<USERNAME>
domain=<DOMAIN>
password=<PASSWORD>

mount as user

By default, CIFS shares are mounted as root. If mounting as user is desirable, `uid` and `gid` arguments can be provided as part of the filesystem options:

{
  fileSystems."/mnt/share" = {
    # ... rest of the filesystem config omitted
    options = ["credentials=/etc/nixos/smb-secrets,uid=1000,gid=100"];
    # or if you have specified `uid` and `gid` explicitly through NixOS configuration,
    # you can refer to them rather than hard-coding the values:
    # options = ["credentials=/etc/nixos/smb-secrets,uid=${config.users.users.<username>.uid},gid=${config.users.groups.<group>.gid}"];
  };
}

Firewall

Samba discovery of machines and shares may need the firewall to be tuned (source): in /etc/nixos/configuration.nix, add:

networking.firewall.extraCommands = ''iptables -t raw -A OUTPUT -p udp -m udp --dport 137 -j CT --helper netbios-ns'';

Browsing samba shares with GVFS

Many GTK-based file managers like Nautilus, Thunar, and PCManFM can browse samba shares thanks to GVFS. GVFS is a dbus daemon which must be running for this to work. If you use Gnome, you have nothing to do as the module already enables it for you, but in less full-featured desktop environments, some further configuration options are needed.

The generic way of enabling GVFS is to add this in /etc/nixos/configuration.nix:

services.gvfs.enable = true;

There are however some special cases.

XFCE

Xfce comes with a slimmed-down version of GVFS by default which comes with samba support compiled out. To have smb:// support in Thunar, we will use GNOME's full-featured version of GVFS:

  services.gvfs = {
    enable = true;
    package = lib.mkForce pkgs.gnome3.gvfs;
  };

No desktop environment

GVFS relies on polkit to gain privileges for some operations. Polkit needs an authentication agent to ask for credentials. Desktop environments usually provide one but if you have no desktop environment, you may have to install one yourself:

Excerpt of /etc/nixos/configuration.nix:

environment.systemPackages = with pkgs; [ lxqt.lxqt-policykit ]; # provides a default authentification client for policykit

DBUS

Furthermore, if you happen to start your Window Manager directly, via .xinitrc, or directly invoke a Wayland compositor such as Sway, you should ensure that you launch dbus at startup in your session and export its environment. If you do not have a dbus session in your environment, you will see errors such as "Operation not supported" when attempting to browse the network.

For example, if you are using .xinitrc, you could invoke dbus-launch:

export `dbus-launch` # starts dbus and exports its address
exec xterm # your prefered Window Manager

(You need to restart your Window Manager to have the changes in .xinitrc to take place.)

If you are using a Wayland compositor like Sway, you can run it under dbus-run-session for the same effect:

dbus-run-session sway

(Because dbus-run-session exits when the child process exits, it is only appropriate to use dbus-run-session with a process that will be running during the entire session. This is the case for Wayland compositors, but is not necessarily true for all configurations of X11 window managers.)

Samba Server

excerpt of /etc/nixos/configuration.nix

services.samba-wsdd.enable = true; # make shares visible for windows 10 clients
services.samba = {
  enable = true;
  securityType = "user";
  extraConfig = ''
    workgroup = WORKGROUP
    server string = smbnix
    netbios name = smbnix
    security = user 
    #use sendfile = yes
    #max protocol = smb2
    # note: localhost is the ipv6 localhost ::1
    hosts allow = 192.168.0 127.0.0.1 localhost
    hosts deny = 0.0.0.0/0
    guest account = nobody
    map to guest = bad user
  '';
  shares = {
    public = {
      path = "/mnt/Shares/Public";
      browseable = "yes";
      "read only" = "no";
      "guest ok" = "yes";
      "create mask" = "0644";
      "directory mask" = "0755";
      "force user" = "username";
      "force group" = "groupname";
    };
    private = {
      path = "/mnt/Shares/Private";
      browseable = "yes";
      "read only" = "no";
      "guest ok" = "no";
      "create mask" = "0644";
      "directory mask" = "0755";
      "force user" = "username";
      "force group" = "groupname";
    };
  };
};

If your firewall is enabled, or if you consider enabling it:

networking.firewall.enable = true;
networking.firewall.allowPing = true;
services.samba.openFirewall = true;

Tip

In order to affect your NixOS system by your nix-language-specific changes you must first evaluate it:

$ nixos-rebuild switch --use-remote-sudo

Samba should startup afterwards.

User Authentication

For a user to be authenticated on the samba server, you must add their password using smbpasswd -a <user> as root.

stopping/restarting the services

# systemctl stop samba
# systemctl start samba
# systemctl restart samba

Use Cases

Apple Time Machine

Example configuration:

services.samba = {
  shares = {
    tm_share = {
        path = "/mnt/Shares/tm_share";
        "valid users" = "username";
        public = "no";
        writeable = "yes";
        "force user" = "username";
        "fruit:aapl" = "yes";
        "fruit:time machine" = "yes";
        "vfs objects" = "catia fruit streams_xattr";
    };
  };
}

Printer sharing

The `samba` packages comes without cups support compiled in, however `sambaFull` features printer sharing support. To use it set the `services.samba.package` option:

services.samba.package = pkgs.sambaFull;

A printer share that allows all members in the local network printing could look like this:

{ pkgs, ... }: {
  services.samba = {
    enable = true;
    package = pkgs.sambaFull;
    extraConfig = ''
      load printers = yes
      printing = cups
      printcap name = cups
    '';
    shares = {
      printers = {
        comment = "All Printers";
        path = "/var/spool/samba";
        public = "yes";
        browseable = "yes";
        # to allow user 'guest account' to print.
        "guest ok" = "yes";
        writable = "no";
        printable = "yes";
        "create mode" = 0700;
      };
  };
  systemd.tmpfiles.rules = [
    "d /var/spool/samba 1777 root root -"
  ];
}

Active Directory Domain Controller

We will setup an AD DC just like the the Samba Wiki. Let's add the following nix config, updating the adDomain, adWorkgroup, adNetbiosName and staticIp according to your needs.

{ config, lib, pkgs, ... }:
with lib;

let
  cfg = config.services.samba;
  samba = cfg.package;
  nssModulesPath = config.system.nssModules.path;
  adDomain = "samdom.example.com";
  adWorkgroup = "SAM";
  adNetbiosName = "SAMDOM";
  staticIp = "10.42.129.160";
in {
  # Disable resolveconf, we're using Samba internal DNS backend
  systemd.services.resolvconf.enable = false;
  environment.etc = {
    resolvconf = {
      text = ''
        search ${adDomain}
        nameserver ${staticIp}
      '';
    };
  };

  # Rebuild Samba with LDAP, MDNS and Domain Controller support
  nixpkgs.overlays = [ (self: super: {
    samba = super.samba.override {
      enableLDAP = true;
      enableMDNS = true;
      enableDomainController = true;
    };
  } ) ];

  # Disable default Samba `smbd` service, we will be using the `samba` server binary
  systemd.services.samba-smbd.enable = false;  
  systemd.services.samba = {
    description = "Samba Service Daemon";

    requiredBy = [ "samba.target" ];
    partOf = [ "samba.target" ];

    serviceConfig = {
      ExecStart = "${samba}/sbin/samba --foreground --no-process-group";
      ExecReload = "${pkgs.coreutils}/bin/kill -HUP $MAINPID";
      LimitNOFILE = 16384;
      PIDFile = "/run/samba.pid";
      Type = "notify";
      NotifyAccess = "all"; #may not do anything...
    };
    unitConfig.RequiresMountsFor = "/var/lib/samba";
  };
  services.samba = {
    enable = true;
    enableNmbd = false;
    enableWinbindd = false;
    configText = ''
      # Global parameters
      [global]
          dns forwarder = ${staticIp}
          netbios name = ${adNetbiosName}
          realm = ${toUpper adDomain}
          server role = active directory domain controller
          workgroup = ${adWorkgroup}
          idmap_ldb:use rfc2307 = yes

      [sysvol]
          path = /var/lib/samba/sysvol
          read only = No

      [netlogon]
          path = /var/lib/samba/sysvol/${adDomain}/scripts
          read only = No
    '';
  };  
}

Tip

In order to affect your NixOS system by your nix-language-specific changes you must first evaluate it:

$ nixos-rebuild switch --use-remote-sudo

After evaluating, you should see that the Samba service crashed because we haven't setup the database yet.

To do that, let's run the following command, updated with your own configuration:

samba-tool domain provision --server-role=dc --use-rfc2307 --dns-backend=SAMBA_INTERNAL --realm=SAMDOM.EXAMPLE.COM --domain=SAMDOM --adminpass=Passw0rd

Then restart the samba service with sudo systemctl restart samba, and you're ready to go!

Troubleshooting

Server log

sudo journalctl -u samba-smbd.service -f

Stale file handle

Trying to read the contents of a remote file leads to the following error message: "Stale file handle". If you have mounted a share via the method described in "cfis mount", adding the option noserverino might fix this problem. [1]

List shares

smbclient --list localhost

This should print

$ smbclient --list localhost 
Password for [WORKGROUP\user]:

	Sharename       Type      Comment
	---------       ----      -------
	public          Disk      
	IPC$            IPC       IPC Service (smbnix)
SMB1 disabled -- no workgroup available

NT_STATUS_INVALID_NETWORK_RESPONSE

The error protocol negotiation failed: NT_STATUS_INVALID_NETWORK_RESPONSE means "access denied". Probably you must fix your server's hosts allow section. Note that localhost is the ipv6 localhost ::1, and 127.0.0.1 is the ipv4 localhost

Mount shares

mount as guest. public is your share name

nix-shell -p cifs-utils
mkdir mnt
sudo mount.cifs -o sec=none //localhost/public mnt

mount as user. user is your username

sudo mount.cifs -o sec=ntlmssp,username=user //localhost/public mnt

sec=ntlmssp should work. for more values, see `man mount.cifs` (search for `sec=arg`)

Permission denied

Maybe check the guest account setting in your server config. The default value is nobody, but the user nobody has no access to /home/user:

$ sudo -u nobody ls /home/user
[sudo] password for user: 
ls: cannot open directory '/home/user': Permission denied

As workaround, set guest account = user, where user is your username