SAMBA, Win95, NT and HP Jetdirect LG #48

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I am running a computer routing lab that is used to teach routing fundamentals on proprietary equipment. It consists of an 18 seat lab with 9 PCs, 1 server and 1 HP LaserJet 4050N with a HP Jetdirect  print server card installed. The server is running Slackware 4.0 with Linux 2.2.6 on it. Eight of the PCs are running WinNT 4.0 SP5 and one PC is running Win95a.

My requirements for the Linux server are as follows:

  • run as a workgroup server not as a primary domain controller
  • run as master browser
  • share each user’s home directory
  • share a common directory among users called public
  • share the server’s CD ROM drive
  • share the HP LaserJet printer

There was a choice of using NFS and configure each client to connect to the Linux server or to use SAMBA and only configure the server. During the normal operation of the lab, the clients are regularly rebuilt, rebooted and reconfigured. It was felt that by running SAMBA services, the Linux server would be transparent to the clients and allow the simplest client install.

This article will describe how I used SAMBA to:

  • setup SAMBA to run on a Slackware Linux server
  • share drives
  • connect and logon from Win95
  • connect and logon from WinNT using encrypted passwords
  • how to connect Linux to HP Jetdirect print server
  • how to share a Linux printer using SAMBA

NOTE: This is not a « howto » type of article but an example of a working configuration and the process used to configure SAMBA

Installing SAMBA

The installation process will vary depending on which distribution of Linux you are running. Under Slackware, select SAMBA during the installation process or if you are adding SAMBA to an existing system, use the pkgtool program.

Change to the Slackware CD, cd to /slakware/N11. Type pkgtool and « Install packages from current directory ». For all other distributions, this article will assume that you have SAMBA properly installed on your system.

SAMBA is started under Slackware by the rc script « /etc/rc.d/rc.samba »:

#
# rc.samba: Start the samba server
#
if [ -x /usr/sbin/smbd -a -x /usr/sbin/nmbd ]; then
  echo "Starting Samba..."
  /usr/sbin/smbd -D
  /usr/sbin/nmbd -D
fi

The smbd program provides SMB/CIFS services to clients. SMB (Server Message Block) is the services that Win95 and NT clients use to connect over networks. The new name for SMB is the Common Internet File System (CIFS).

The nmbd program is a NETBIOS name server to allow NETBIOS over IP naming services to clients.

Typing « ps -aux » at the command prompt allows us to view the processes that are running and to see if smbd and nmbd are actually present:

USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 0.0 0.2 220 128 ? S Oct21 0:02 init
root 2 0.0 0.0 0 0 ? SW Oct21 0:00 [kflushd]
root 3 0.0 0.0 0 0 ? SW Oct21 0:00 [kpiod]
root 4 0.0 0.0 0 0 ? SW Oct21 0:00 [kswapd]  root 101 0.0 0.5 1544 380 ? S Oct21 0:00 /usr/sbin/smbd -D
root 103 0.0 0.9 1196 584 ? S Oct21 0:03 /usr/sbin/nmbd -D  root 8113 0.4 0.9 1164 616 ttyp0 S 11:14 0:00 -bash
root 8120 0.0 1.1 2272 744 ttyp0 R 11:14 0:00 ps -aux

SAMBA Configuration File

The configuration file for SAMBA is /etc/smb.conf and there are many examples configurations available in /usr/doc/samba-2.0.3/examples.

The /etc/smb.conf can be divided into 3 general sections: The Global section deals with global parameters such as workgroup name, netbios name, IP interface used. For example:

# Global parameters

        workgroup = E328                # workgroup name
        netbios name = E328-00          # Linux server's netbios name
        server string = %h - Linux Samba server         # comment shown in Win's Network Neighborhood detail view
        interfaces = 192.168.1.3/24     # NICs + subnet mask (24 = 255.255.255.0) 
        encrypt passwords = Yes         # Required for NT (Win95 will work with encrypted or not)
        null passwords = No             # Must have a password
        log file = /var/log/samba.      # location of samba log files (many!)
        max log size = 50               # maximum size of each log file
        socket options = TCP_NODELAY    # Speeds up convergence of netbios
        os level = 33                   # Gives a higher browse master "priority"
        preferred master = Yes          # This server is the browsemaster
        guest account = pcguest         # guest account name
        hosts allow = 192.168.1. 127.   # networks allowed to access this server using SMB

The Shares section deals with sharing file directories. For example:

[homes]
        comment = Home Directories      # comment shown in Win's Network Neighborhood detail view
        path = %H                       # automatically display user's home directory as SMB share
        valid users = %S                # Only user is allowed to access this directory
        read only = No                  # can read/write
        create mask = 0750              # permissions given when creating new files
        browseable = No                 # only show user's home directory not "homes" folder

[public]
        comment = Public Files          # comment shown in Win's Network Neighborhood detail view
        path = /home/ftp/pub            # path to public directory
        guest ok = Yes                  # anyone can access this directory

[cdrom]
        comment = Cdrom on E328-00      # comment shown in Win's Network Neighborhood detail view
        path = /cdrom                   # path to cdrom drive
        guest ok = Yes                  # anyone can access cdrom drive, public share

The Printers section deals with sharing printers. For example:

[lp] 
        comment = E328-Laser            # comment shown in Win's Network Neighborhood detail view
        path = /var/spool/samba         # path to spool directory
        print ok = Yes                  # allowed to open, write to and submit to spool directory

You can manually create the /etc/smb.conf file if you know what each of the entries mean or you can use the web GUI called SWAT (SAMBA Web Administration Tool). An added bonus of using SWAT was the online help files that described each of the choices available. I understand that SWAT is installed automatically with all versions of SAMBA from 2.0 and up.

Running SWAT

The following instructions are taken directly from the /usr/doc/samba-2.0.3/swat/README file:

Running via inetd
-----------------

You then need to edit your /etc/inetd.conf and /etc/services to enable
SWAT to be launched via inetd. 

In /etc/services you need to add a line like this:

swat    901/tcp

the choice of port number isn't really important except that it should
be less than 1024 and not currently used (using a number above 1024
presents an obscure security hole depending on the implementation
details of your inetd daemon).

In /etc/inetd.conf you should add a line like this:

swat    stream  tcp     nowait.400      root    /usr/local/samba/bin/swat swat

One you have edited /etc/services and /etc/inetd.conf you need to send
a HUP signal to inetd. On many systems "killall -1 inetd" will do this
on others you will need to use "kill -1 PID" where PID is the process
ID of the inetd daemon.



Launching
---------

To launch SWAT just run your favourite web browser and point it at
http://localhost:901

Note that you can attach to SWAT from any IP connected machine but
connecting from a remote machine leaves your connection open to
password sniffing as passwords will be sent in the clear over the
wire.

You should be prompted for a username/password when you connect. You
will need to provide the username "root" and the correct root
password.

Once SWAT is up and running, you should see the following:

The menu buttons are pretty self-explanatory and there are excellent help screens available. A quick break down of the menus:

  • Home: Takes you to the main page
  • Globals: Allows you to configure the global parameters
  • Shares: Allows you to configure directory shares
  • Printers: Allows you to configure printers based on the /etc/printcap file
  • Status: Allows you to start and stop the smbd and nmbd server and show the status.
  • View: Views the /etc/smb.conf file
  • Password: Allows you to change the server password and account.

Whenever changes are made to the configuration in the Global, Shares and Printer section, the changes must be committed using the commit button/icon on the respective page. Otherwise the /etc/smb.conf file is not modified.

Once the changes are committed (/etc/smb.conf modified), the smbd and nmbd server should be restarted. The Status menu has options that allow the servers to be stopped and restarted.

I found that a good way of understanding the process that was going on was to view the /etc/smb.conf file as I made changes using the View button in SWAT.

Usernames

It is very important that the usernames and passwords are the same for both the Windows and Linux environments. The synchronization of the Linux passwords with the SMB encrypted passwords is done using the shell script mksmbpasswd.sh which is found in the /usr/lib/samba/private.

Lire aussi...  Unioncamere Emilia-Romagna: an Italian Public Administration Using Linux Issue 23

Note: For Slackware, the directory for SAMBA is /usr/lib not the standard /usr/local directory.

The following information is taken from the /usr/doc/samba-2.0.3/docs/textdocs/ENCRYPTION.txt file:

The smbpasswd file.
-------------------

In order for Samba to participate in the above protocol it must
be able to look up the 16 byte hashed values given a user name.
Unfortunately, as the UNIX password value is also a one way hash
function (ie. it is impossible to retrieve the cleartext of the users
password given the UNIX hash of it) then a separate password file
containing this 16 byte value must be kept. To minimise problems with
these two password files, getting out of sync, the UNIX /etc/passwd and
the smbpasswd file, a utility, mksmbpasswd.sh, is provided to generate
a smbpasswd file from a UNIX /etc/passwd file.

To generate the smbpasswd file from your /etc/passwd file use the
following command :-

cat /etc/passwd | mksmbpasswd.sh >/usr/local/samba/private/smbpasswd

The problem that I found with this step was that I expected that it would automatically recognize shadowed passwords and place them in the smbpasswd file. Unfortunately, it didn’t and I had to manually enter in the passwords using the smbpasswd command. Luckly, I had only only about 10 passwords to enter in. There is probably a method of doing this automatically and I am just not aware of it.

Once completed, I was able to use Network Neighborhood and point and click on the Linux directory shares without being prompted for a username and password.

Configuring the HP JetDirect Card using Linux

Getting Linux and the HP JetDirect card to work was surprisingly easy. The JetDirect card is a print server card that fits into the HP 4050N printer. The first step is to configure the HP JetDirect card and printer. The standard install disk does not contain support for Linux but there is a WebAdmin tool that you can download from HP’s website: http://www.hp.com/support/net_printing. I chose to do it manually by using telnet and the built-in webserver of the JetDirect card.

Telneting to the JetDirect Card

In order to telnet to the JetDirect card, you need to configure the printer’s IP address. The default IP address is 192.0.0.192 which most likely will not be a valid address on your network. The HP 4050N printer allows you to to configure the IP address through the printer’s status window. Select « JetDirect Menu » from the Menu button and then follow the directions for configuring the network. After the IP address is set, configure the subnet mask in a similar manner.

Telnet to your printer’s IP address. You have two choices when telnetting in, you can view the current settings of the printer by typing « / » or viewing the help menu using « ? » as shown by the following:

Please type "?" for HELP, or "/" for current settings >/ ===JetDirect Telnet Configuration=== Firmware Rev. : G.07.20 MAC Address : 00:10:83:1b:41:c7 Config By : USER SPECIFIED IP Address : 192.168.1.10 Subnet Mask : 255.255.255.0 Default Gateway : 192.168.1.1 Syslog Server : Not Specified Idle Timeout : 120 Seconds Set Cmnty Name : notachance Host Name : E328-LASER DHCP Config : Disabled Passwd : Enabled IPX/SPX : Disabled DLC/LLC : Enabled Ethertalk : Disabled Banner page : Disabled >? To Change/Configure Parameters Enter: Parameter-name: value  Parameter-name Type of value ip: IP-address in dotted notation subnet-mask: address in dotted notation default-gw: address in dotted notation syslog-svr: address in dotted notation idle-timeout: seconds in integers set-cmnty-name: alpha-numeric string (32 chars max) host-name: alpha-numeric string (upper case only, 32 chars max) dhcp-config: 0 to disable, 1 to enable ipx/spx: 0 to disable, 1 to enable dlc/llc: 0 to disable, 1 to enable ethertalk: 0 to disable, 1 to enable banner: 0 to disable, 1 to enable Type passwd to change the password. Type "?" for HELP, "/" for current settings or "quit" to save-and-exit. Or type "exit" to exit without saving configuration parameter entries

The first thing that you should do is type « passwd » and add an administrator password to the printer. Next configure the default gateway and then the host name. The rest will be configured using the printer’s built-in webserver.

HP JetDirect Webtool

The HP JetDirect webtool has 6 menu tabs available:

  • Status Tab

    Displays current status of printer including network stats

  • Identity

    Displays current software/hardware revisions, host name, IP address, etc..

  • Configuration

    Allows configuration of TCP/IP (default protocol), IPX/SPX, DLC/LLC, Ethertalk and SNMP.

  • Security

    Allows changing of the administrator password and SNMP community name.

  • Diagnostics

    Displays statistics and information on TCP/IP, IPX/SPX, DLC/LLC, Ethertalk, printer and Jetdirect.

  • Support

    Takes you to the HP support website.

Printing from Linux to JetDirect

In order to print from Linux to the JetDirect print server, an entry was made in the /etc/printcap file. I made a new spool directory called /usr/spool/lj4050n but the default /usr/spool/lpd should really be used. The directory /usr/spool is a softlink to /var/spool.

The following is a listing of the /etc/printcap file that was used to communicate with the HP JetDirect print server:

# HP Laserjet 4050n

lp|lj4050n:\
        :lp=/dev/null:sh:\
        :mx#0:\
        :sd=/usr/spool/lj4050n:\
        :rm=e328-laser.domainname.com:rp=text:

Where:

  • lp|lj4050n:\

    indicates the default default printer « lp » with an alias/description of « lj4050n ». If there was a space in the alias, it would automatically be detected as a description.

  • :lp=/dev/null:sh:\

    indicates that the printer is not connected to a physical port

  • :mx#0:\

    indicates that there is no maximum file size to send to the printer

  • :sd=/usr/spool/lj4050n:\

    indicates the path to the spool directory

  • :rm=e328-laser.domainname.com:rp=text:

    indicates the domain name of the printer to send print jobs to and what format to send it in. The choices were text or raw for HP printers. I found that the printer was intelligent enough that it automatically detected whether it was a text file, postscript file or PCL file.

Configuring Windows for Linux Shared Printer

>From Network Neighborhood, double-click on the Linux server’s shared printer icon. Windows will ask you to configure the printer. I shared the printer’s configuration CD on the Linux box and went to the disk1 folder to find the INF file. The printer configuration/installation will stop and display a message something to the tune that it « can’t find disk2 » just go up a directory to find the disk2 folder. It will finish the installation and you are done. I usually run a Print Testpage to ensure that it works properly.

The normal installation procedure is to run the setup utility from the CD. This installs megabytes of data on to the client which was not what I wanted. I only wanted the print driver and found that the above method gave me a quick, clean and simple printer configuration.

Summary

It was surprisingly easy to configure SAMBA and have it meet the lab’s objectives. When I first ran SAMBA, it took less than 10 minutes to communicate with Win95. This was amazing as I had no prior experience with it.

In configuring the lab environment, I ran into a few problems, some annoying and some took a bit of work to sort but all were solved.

An example of one of the annoying problems was having the [homes] folder show up as a share on a client. It was identical to the client’s home directory. Selecting « Browseable = No » in the Global section of /etc/smb.conf solved that.

The most frustrating problem was finding out the the smbpasswd file did not automatically convert passwords from shadow files. I kept getting asked for a username and password whenever I tried to connect to a network share. All the documentation indicated that I was doing everything correct. Manually entering each username’s password using the smbpasswd program solved this. I am sure that there is an automatic process for this, as this would not be acceptable if there more than my 10 generic user accounts.

All in all, I was able to configure the network quicker and easier than if I used an NT server and the Linux server is totally transparent to the user. Here’s an interesting point: this article has taken longer to write than it did to configure the network.