Background

Demilitarized Zone (DMZ) Services

Firewall/Gateway

Internal Services

Internal Clients

Future Plans
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Network and Computer Services: Internal Services

A rack-mounted computer supplied by the now defunct VA Linux Inc. acts as the main file server for the entire subnet. The model we choose has four symmetric Pentium Xeon 550 MHz processors and 1 GB of RAM. Of course, by Moore's law this is already becoming an amusing reminder of how slow computers used to be. This compter has two SCSI (Small Computer System Interface) http://www.computerhope.com/help/scsi.htm http://www.computerhope.com/help/raid.htm RAID (Redundant Array of Inexpensive Disks) devices providing almost a terabyte of memory.

The main services we provide internally are file sharing, printing, and job scheduling.

File Sharing

After establishing a fast, secure, and dedicated network, we wished to provide a mechanism for consistent and transparent file access to multiple platforms. For the BIC, the most important platforms for file sharing are the various UNIX variants. The Network File System (NFS) and the Network Information System (NIS) were introduced by Sun Microsystems in 1985 to build distributed computing systems that are both consistent in appearance and transparent in the way file are accessed and shared. Most UNIX systems (including Linux) have very good support for these protocols.

  • NFS is a transparent, distributed network file system. The NFS Server exports one or more filesystems that are mounted by one or more NFS clients, the mounted filesystem behaves just like a local disk to the client machine. This makes life easier for both the administrator and the user. For the administrator, it reduces the overhead incurred to keep "identical" files and directories in synch across several systems. For the user, it provides a transparent mechanism whereby their files and data are easily accessible regardless of which machine they happen to use.

  • NIS provides a distributed database for common configuration files. The NIS Server manages and distributes common configuration information to the NIS clients so that the clients don't have to use local copies. For example, /etc/passwd which contains the user name and password information can maintained on the NIS Server and provided to clients rather than requiring each client machine to be updated everytime a user is added to the system.

  • NTP (Network Time Protocol), while not essentially tied to NFS/NIS services, is none the less important for their proper functioning.

Of course, UNIX is not the only environment to support file sharing. Microsoft Windows has a form of network file system based on Session Message Blocks (SMB). Additionally, MacOS uses AppleTalk. Fortunately, Linux supports these protocols as well.

Printing

Printing is one of the most troublesome task for administrators to deal with. Up until recently this was especially so with UNIX systems, which relied on the ancient Line Printing (LP) system. This has recently been remedied with a new printing system from Easy Software Products (ESP) .

Job Scheduling

This component was one of the driving factors in our choosing to go with Linux.

  • Voxbo's primary function as a server is to schedule tasks to be run on the various Linux workstations on the subnet in order to optimize the usage of processing power.