Accessing Shares with smbsh and smbfs

The smbclient program is not the only way to access Windows shares. Linux provides two other alternatives: the smbsh shell and the amazingly useful smbfs file system.

The first option is smbsh, which is actually just a bash shell invoked inside a Samba "wrapper." The wrapper is a shared library that intercepts file- related system calls in order to create a virtual directory at /smb. Any dynamically linked program run under this environment will be able to access a Windows network as if it were part of the local file system.

The virtual directory is organized as /smb/<server>/<share>/< path >/<file>. For example,

$ ls /smb

will list all available machines in a workgroup, and the command

$ cp /smb/HOMER/site-local/sql/tables.sql ./

will copy a file on //HOMER/site-local to the current directory. Keep in mind that smbsh will not work with statically linked programs, and in fact the Samba documentation refers to the SMB "wrapper" as "a hack."

Fortunately, there is a better option available: Windows shares can actually be mounted on a Linux file system just as if they were local partitions! This is equiva lent to the Windows and Netware operations of mapping a network volume. However, instead of adding a volume as a separate drive letter, the share can be mounted anywhere on the Linux file system. The smbfs kernel module and the smbmount utility are responsible for this bit of magic. Support for Samba file systems is included in the kernel source distribution, but you may need to enable that support in the kernel configuration and recompile. The configuration option is under the Filesystems/ Network filesystems menu. Kernel recompilation is covered in Chapter 1 .

# insmod smbfs

# smbmount //KEARNEY/C$ /mnt/remote-cdrom

# df

Filesystem 1k-blocks Used Available Use% Mounted on

/dev/hdc1 101075 40254 55602 42% /

/dev/hdc5 147740 32032 108079 23% /var

/dev/hdc6 147740 2039 138072 1% /tmp

/dev/hdc7 1981000 1251183 627405 67% /usr

/dev/hdc4 5723816 3859608 1567809 71% /home

//kearney/c$ 101075 40254 55602 42% /mnt/kearney-cdrive

The insmod ensures that the smbfs kernel module is installed. Of course, this step is not necessary if SMB file system support is precompiled into the kernel. The standard mount command cannot build the appropriate data structures necessary for the smbfs modules, so Samba provides the smbmount command. The syntax is similar, but the first argument should be a share name instead of a device name . Share names ending with a dollar sign are not shown by Windows Explorer. This is a Microsoft-specific way to implement "hidden" shares. Samba will always show these shares, however.

In the case of authenticated shares (and none of your shares allow anonymous logins, right?), the username and domain required to connect to the share can be provided with the -o option:

# smbmount //KEARNEY/C$ /mnt -o username=pcurtis,workgroup=WORKGROUP, uid=root,gid=staff,fmask=0664,dmask=0775

 password:

You will need to enter a password to complete the connection. The other options set the user, group , and permissions under which the mounted files will appear. In this example, the SMB file system is made available read-only to any user on the machine, except for root and any user in the group staff.