Memory Communication Services

System Security

I aim to offer straightforward cost effective methods of organizing computer data and backup in order to minimize the problems that arise when things go wrong.

 

Problems – Analysis of their Causes

Your most likely “disaster” is due to overwriting or erasing work that you later found that you needed. You may expect other problems to be broken down according to the following categories: -

Source: Universal BUSLink Corporation

In order of likelihood, (most likely event first) : -

Human error: system or user software appears to fail for no apparent reason, though it is probably brought on by system reconfiguration, or accidental damage to files by the user.

Hardware fails due to old age: a hard drive crash is the most likely cause, others include processor overheating due to fan failure etc.

Software malfunction – which is hard to separate from Human error (see above).

Theft: hardware can be replaced, also application software, but user data needs to be archived.

Virus infection is generally from Internet use, in particular carried by e-mail attachments. See here for further details.

Other damage - fire, water ingress etc.

 

Solutions

Software can be split into two components. User data is volatile and needs frequent backup. Operating systems and programs change relatively infrequently. So their storage and backup can conveniently be done separately. Which is just as well for complications arise when a running operating system tries to back itself up.

Hardware can be designed for fault tolerance – with the most fault prone monitored or duplicated. (typically processor and system temperature is monitored and automatic shutdown enabled for overheating. Hard drives are now economic to use in pairs duplicating data for security. See RAID (Redundant Arrays of Independent Disks). Power supplies are simplest provided for by over-specifying workload and choosing products from top quality manufacturers.

Server costs depend very much upon their workload, the use to which they are put, and the need for operating without interruption. For typical file sharing and mail for 25 users, the hardware cost would be in the range of £600 - £1500. Software to run it would be £1500 for Microsoft Small Business Server + Client Licenses.   A Linux software alternative is available at zero purchase price - though Microsoft assert the total cost of ownership is likely to be cheaper for their product.

Backup can be done by storage to tape, DVD or CD, or onto an external hard drive. Tape units cost in the order of £300 for the 25 user scenario above.  They have a limited life due to reliability considerations but have the advantages that once set up they are easy to use and provide off-site security.  DVD/CD is cheap to buy but uses one-off media and the storage quantity is small.  External (USB) hard drives provide an economic alternative and synchronisation can be set up between them and the server hard drives.

 

Viruses, Worms and Trojans

Broadly speaking, viruses are self-replicating programs that infect other programs and perform malicious tasks specified by the virus writer. Worms are free-running programs that exploit network connections to copy themselves onto other machines. Trojans are malicious programs installed by the user in the mistaken belief that they served another legitimate purpose.

The above is a necessary generalization for the boundaries between them are blurred.

In Windows it's essential to protect against them using an Antivirus program and a Firewall. Different Operating Systems are less vulnerable due in part to their lower market penetration making them a less attractive target for virus writers. But the fundamental difference with Unix type systems eg Linux is that users typically are assigned permissions to run programs but do not have authority to make changes to the system. Consequently they (and any viruses they collect) have similarly limited scope to damage the system. Note that this can be similarly set up in Windows XP and is standard in Vista see Microsoft Security Paper.

Company policy on permitted use of their computer systems can also play a part in antivirus protection, for many if not most infections on business machines originate from non-business use of them.

 

Contact me for further details ~~~