≡ Menu

Samba (SMB/CIFS)

Linux Changing DNS Search Order

Q. How do I change DNS search order in Linux? In order to improve performance I need to make changes.

A. Under Linux you need to use /etc/nsswitch.conf file which is used by system databases and Name Service Switch configuration file

Various functions in the C Library need to be configured to work correctly in the local environment. Tradition ally, this was done by using files (e.g., ‘/etc/passwd’), but other nameservices (like the Network Information Service (NIS) and the Domain Name Service (DNS)) became popular, and were hacked into the C library, usually with a fixed search order.

Step # 1: /etc/nsswitch.conf

Open /etc/nsswitch.conf file using text editor:
# vi /etc/nsswitch.conf

Look for hosts:
hosts: files dns mdns4

Set above order as per your requirement. Close and save the file.

host.conf - resolver configuration file

The file /etc/host.conf contains configuration information specific to the resolver library. It should contain one configuration keyword per line, followed by appropriate configuration information.

Open /etc/host.conf file
# vi /etc/host.conf
Find order line which specifies how host lookups are to be performed. It should be followed by one or more lookup methods, separated by commas. Valid methods are bind (dns server), hosts (/etc/hosts file), and nis (old method).
order hosts,bind

Save and close the file.

See the nsswitch.conf and host.conf man pages for details.

Q. I’m using NAS server share to make a backup of my webserver. However samba is not allowing me to backup of large files (2GB+).

My Samba share mount command is as follows:
smbmount //nas1.domain.com/sharename /datanas -o username=LOGINNAME,password=LOGINPASSWORD

Now if I copy file called /var/log/httpd/access.log (which is 3.5 GB file):
cp /var/log/httpd/access.log /datanas

I get ab error - file size limit exceeded

How do I solve this problem and copy large files to NAS samba share?

A. Linux kernel use smbfs.ko/smbfs.o module and it does not support file sizes greater than 2 GB. This is well known problem.

Mount your NAS samba share with lfs (large file system) option. General syntax is as follows:
smbmount //Hostname/Username /local/mountpoint -o username=username,password=password,lfs

For example:
# smbmount //nas1.domain.com/sharename /datanas -o username=LOGINNAME,password=LOGINPASSWORD,lfs

Where,

  • //nas1.domain.com/sharename : Server and Share name
  • /datanas : Local mount point
  • -o username=LOGINNAME,password=LOGINPASSWORD,lfs : Specify login, password and lfs options

Now you should be able to copy large files w/o a problem.

Samba Add a User

I am using Fedora Linux and I would like to add a user called joe to Samba. How do I add a user SMB share? How can I add a users to Samba?
[click to continue…]