IPX is commonly used to mount NetWare volumes in the Linux
filesystem. This allows file-based data sharing between other
operating systems and Linux. Volker Lendecke developed the NCP client
for Linux and a suite of associated tools that make data sharing
possible.
In an NFS environment, we'd use the Linux mount
command to mount the remote filesystem. Unfortunately, the NCP
filesystem has unique requirements that make it impractical to build
it into the normal mount. Linux has an
ncpmount command that we will use instead. The
ncpmount command is one of the tools in Volker's
ncpfs package, which is available prepackaged in
most modern distributions or in source form from ftp.gwdg.de in the
/pub/linux/misc/ncpfs/ directory. The version
current at the time of writing is 2.2.0.
Before you can mount remote NetWare volumes, you must ensure your IPX network
interface is configured correctly (as described earlier). Next, you must know
your login details on the NetWare server you wish to mount; this includes
the user ID and password. Lastly, you need to know which volume you wish
to mount and what local directory you wish to mount it under.
A simple example of ncpmount usage looks like this:
# ncpmount -S ALES_F1 -U rick -P d00-b-gud /mnt/brewery |
This command mounts all volumes of the
ALES_F1
fileserver under the
/mnt/brewery directory,
using the NetWare login
rick with the password
d00-b-gud.
The ncpmount command is normally setuid to
root and may therefore be used
by any Linux user. By default, that user owns the connection and
only he or the root user will
be able to unmount it.
NetWare embodies the notion of a volume, which is
analogous to a filesystem in Linux. A NetWare volume is the logical
representation of a NetWare filesystem, which might be a single disk
partition be spread across many partitions. By default, the
Linux NCPFS support treats volumes as subdirectories of a larger
logical filesystem represented by the whole fileserver. The
ncpmount command causes each of the NetWare
volumes of the mounted fileserver to appear as a subdirectory under
the mount point. This is convenient if you want access to the whole
server, but for complex technical reasons you will be unable to
re-export these directories using NFS, should you wish to do so. We'll
discuss a more complex alternative that works around this problem in a
moment.
The ncpmount has a large number of command line options
that allow you quite a lot of flexibility in how you manage your NCP mounts.
The most important of these are described in
Table 15-2.
Table 15-2. ncpmount Command Arguments
| Argument | Description |
|---|
–S server | The name of the fileserver to mount. |
–U user_name | The NetWare user ID to use when logging in to the fileserver. |
–P password | The password to use for the NetWare login. |
| –n | This option must be used for NetWare logins that don't have a password
associated with them. |
| –C | This argument disables automatic conversion of passwords to uppercase. |
| –c client_name | This option allows you to specify who owns the connection to the
fileserver. This is useful for NetWare printing, which we will discuss in
more detail later. |
| –u uid | The Linux user ID that should be shown as the owner of files in the
mounted directory. If this is not specified, it defaults to the
user ID of the user who invokes the ncpmount
command. |
| –g gid | The Linux group ID that should be shown as the owner of files in the
mounted directory. If this is not specified, it will default to the
group ID of the user who invokes the ncpmount
command. |
| –f file_mode | This option allows you to specify the file mode (permissions) that
files in the mounted directory should have. The value should be
specified in octal, e.g., 0664. The permissions
that you will actually have are the file mode permissions
specified with this option masked with the permissions that your
NetWare login ID has for the files on the fileserver. You must have
rights on the server and rights specified by this option in order to
access a file. The default value is derived from the current
umask. |
| –d dir_mode | This option allows you to specify the directory permissions in the
mounted directory. It behaves in the same way as the
–f option, except that the default permissions are
derived from the current umask. Execute permissions
are granted where read access is granted. |
| –V volume | This option allows you to specify the name of a single NetWare
volume to mount under the mount point, rather than mounting all volumes of
the target server. This option is necessary if you wish to re-export a
mounted NetWare volume using NFS. |
| –t time_out | This option allows you to specify the time that the NCPFS client will wait
for a response from a server. The default value is 60mS and the timeout is
specified in hundredths of a second. If you experience any stability problems
with NCP mounts, you should try increasing this value. |
| –r retry_count | The NCP client code attempts to resend datagrams to the server
a number of times before deciding the connection is dead. This option allows
you to change the retry count from the default of 5. |
It is somewhat of a security risk to be putting a password on the
command line, as we did with the ncpmount command.
Other active, concurrent users could see the password if they happen
to be running a program like top or
ps. To reduce the risk of others seeing and
stealing NetWare login passwords, ncpmount is able
to read certain details from a file in a user's home directory. In
this file, the user keeps the login name and password associated with
each of the fileservers he or she intends to mount. The file is called
~/.nwclient and it must have permissions of
0600 to ensure that others cannot read it. If the
permissions are not correct, the ncpmount command
will refuse to use it.
The file has a very simple syntax. Any lines beginning with a #
character are treated as comments and ignored.
The remainder of the lines have the syntax:
fileserver/userid password |
The
fileserver is the name of the
fileserver supporting the volumes you wish to mount. The
userid is the login name of your account on
that server. The
password field is
optional. If it is not supplied, the
ncpmount
command prompts users for the password when they attempt the
mount. If the
password field is specified
as the – character, no password is used; this is equivalent
to the
–n command-line argument.
You can supply any number of entries, but the fileserver field must be
unique. The first fileserver entry has special significance. The
ncpmount command uses the –S
command-line argument to determine which of the entries in
~/.nwclient to use. If no server is specified
using the –S argument, the first server entry
in ~/.nwclient is assumed, and is treated as your
preferred server. You should place the fileserver you mount most
frequently in the first position in the file.
Let's look at a more complex ncpmount example involving
a number of the features we've described. First, let's build a simple
~/.nwclient file:
# NetWare login details for the Virtual Brewery and Winery
#
# Brewery Login
ALES_F1/MATT staoic1
#
# Winery Login
REDS01/MATT staoic1
# |
Make sure its permissions are correct:
Let's mount one volume of the Winery's server under a subdirectory of a
shared directory, specifying the file and directory permissions such that
others may share the data from there:
$ ncpmount -S REDS01 -V RESEARCH -f 0664 -d 0775 /usr/share/winery/data/ |
This command, in combination with the
~/.nwclient file
shown, would mount the
RESEARCH volume of the
REDS01 server onto the
/usr/share/winery/data/ directory using the NetWare
login ID of
MATT and the password retrieved
from the
~/.nwclient file. The permissions of the
mounted files are
0664 and the directory permissions
are
0775.
