Linux in a Windows Workstation Environment, Part II: Local Network Support
The computer club's Web site is used to publish scheduling information for classes, meetings and presentations. The navigation bar of this site also contains links to some popular sites, including the Web mail sites for AOL, Juno, Hotmail and Yahoo, as well as the search sites for Google and Hotbot. Because this site is used as the home page for all computers in the lab, it is accessed many, many times per day. To reduce bandwidth on the external line, a Web server has been configured to serve a local copy of this site. The effort has been minimal, as we do not use any CGI scripting nor do we need any logging.
By storing the Web content locally, our Web master can edit changing content without connecting to the external site. Each evening cron, the Linux version of the task scheduler, starts a script that produces a list of the Web site files that have been altered within the past 24 hours. It then transfers them to the external site using using the wput command, an indirect way to use FTP. To insure controlled write access to the Web material, it is stored in a password-protected Samba share, to be discussed later.
I use the Apache Web server as the server for our intranet. Although the latest version, 2.0, implements a number of new security features, my initial attempts to use the newest software failed. We use only simple Web pages and have no security issues, as the server is accessed only from the internal network. Therefore, I am using the older V1.3 release. The control file, httpd.conf, can include a large number of parameters; however, only a small number needed to be tailored for my system. The first of these is the server type. Under Linux, the daemon can be triggered by the Internet super daemon, inetd, or it can be started as a standalone program. I chose the latter option.
The next parameter to be configured is the root directory for the configuration, error and log files.
We also specify the IP address and port. If this parameter was not specified, the program would listen on all interfaces. However, I explicitly wish to exclude the external interface but use the standard port.
We also need to specify the directory in which our Web pages are stored, as well as a Directory stanza to allow everyone to access that material.
DocumentRoot "/home/web" <Directory "/home/web"> Order allow,deny Allow from all </Directory>
The combination of local home page serving and the cache-only name server greatly decrease the workstation response time and cut the traffic on the external network. The benefits of each greatly outweigh the minimal effort required to set them up.
To supply file and print services for the Windows workstations, we use Samba. To quote samba.org, "Samba is an Open Source/Free Software suite that provides seamless file and print services to SMB/CIFS clients. Samba is freely available, unlike other SMB/CIFS implementations, and allows for interoperability between Linux/Unix servers and Windows-based clients." Using this package, our Linux computer offers printer shares for both printers and three distinct file shares.
The Samba configuration file, which normally is /etc/samba/smb.conf, contains definitions for global parameters in a section named [global]. In this section, I have annotated the parameters defined on our system:
[global] max smbd processes = 40 # one server process for each workstation workgroup = MRLAB # name reported to network browser netbios name = server # NetBIOS name reported by server security = share # needed for guest services to work hosts allow = 10.10.10.0/24 # limit to our network guest account = nobody # the guest has the privileges of this user log file = /usr/local/samba/var/log smb passwd file = /usr/local/samba/lib/smbpasswd max log size = 500 # size in kB preferred master = yes # this machine is master for net domain master = yes # we have no other domain servers deadtime = 5 # no. of minutes till connection expires server string = Samba # name in printer comment box on Windows interfaces = 10.10.10.1/24 # serve only our internal network wins support = No # no Wins name resolution show add printer wizard = yes # Wizard is shown on NT/XP/2K clients max print jobs = 20 # number of simultaneous print jobs printer admin = root # only the superuser can manipulate printers null passwords = yes # we want to have no password for some users load printers = no # do not create shares automatically printing = bsd # BSD-type printing
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
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