Sunday, May 10, 2015

Samba Server in CentOS / RHEL 7

Samba is comprised of three daemons: smbd, nmbd, and winbindd. 

  • smbd daemon provides file sharing and printing services to clients as well as user authentication, resource locking, and data sharing through the SMB protocol. The default ports of smbd are 139 tcp and 445 tcp. The smbd daemon is controlled by the smb service.
  •  The nmbd daemon deals with NetBIOS protocol. It means it participates in the browsing protocols that make up the Windows Network Neighborhood. The default port for NMB is 137 udp. The nmbd daemon is controlled by the nmb service.
  • The winbind service resolves user and group information received from a Windows server. This makes Windows users and groups information understandable by our Linux system. The winbindd daemon is controlled by the winbind service and does not require the smb service to be started in order to operate. 
To install samba: 
# yum install samba*
Then create a directory to share: 
# mkdir /samba_share
# chmod 777 /samba_share
Change the SELinux file context so that it can be shared:
# chcon -t samba_share_t /samba_share/
or easily disable SE Linux by editing /etc/sysconfig/selinux or /etc/selinux/config if security is not important for you. 

You may need to create a user: 
# useradd behnam
# paaswd behnam
# smbpasswd -a behnam
Put the following lines in /etc/samba/smb.conf to create a share directory:

  comment = Samba share
  path = /samba_share
  valid users = behnam behdad
  public = no
  browseable = yes
  valid users = bp
  writable = yes
  create mask = 0765

And enable and then start the service:
# systemctl enable smb.service
# systemctl start smb.service
Do not forget to open the appropriate ports on firewall: 
#firewall-cmd –-permanent –-add-service=samba
#systemctl restart firewalld

To specify the Windows workgroup and a brief description of the Samba server:

server string = Behnam's Samba Server

Important: To set up a Windows domain member server, you must first join the domain using the net join command before starting the smb service. Also you'd better run winbind service before smbd.

Mote: When the /etc/samba/smb.conf file is changed, Samba automatically reloads it after a few minutes. Issuing a manual restart or reload is also effective.

Sample config file:

Another simple sample file might be as follow: 

    workgroup = WORKGROUP
    server string = my Samba server
    netbios name = bp-samba
    name resolve order = bcast host
    dns proxy = no

    log file = /var/log/samba/%m.log

    create mask = 0664

    directory mask = 0775

    force create mode = 0664

    force directory mode = 0775

    security = user

    map to guest = Bad User

    max log size = 50


   path = /home/samba_share
   public = yes
   only guest = yes
   writable = yes

Related Tools:

If you want to access the share folder via a Linux client: 
$ smbclient //<hostname>/<share-name> -U <username>
Note: If the -U switch is not used, the username of the current user is passed to the Samba server.
To exit smbclient, type exit at the smb:\> prompt.

Mounting Windows or Samba share in Linux: 
# mount -t cifs //<servername>/<share-name> /mnt/point/ -o username=<username>,password=<password>
Note 1: make sure the cifs-utils rpm is installed on your system.

Note 2: For permanent mount, create a proper entry in /etc/fstab

The following example displays a list of the available shares for a host named behnam-pc:
$ net -l share -S behnam-pc
The following example displays a list of Samba users for a host named behnam-pc:
$ net -l user -S behnam-pc
The nmblookup tool resolves NetBIOS names into IP addresses. nmblookup broadcasts its query on the local subnet until the target machine replies.
$ nmblookup anar
pdbedit is a tool to manage accounts located in the SAM database:
$ pdbedit -a behnam
The smbcacls program modifies Windows ACLs on files and directories shared by a Samba server or a Windows server:
# smbcacls <//server/share> <filename> <options> 
The smbstatus program displays the status of current connections to a Samba server.

The testparm program checks the syntax of the /etc/samba/smb.conf file. it also displays a summary of your smb.conf config file after testing. 

The wbinfo program displays information from the winbindd daemon. The winbindd daemon must be running for wbinfo to work.