Few security tips on computer systems.

[balda]

Electrical engineering checking in

my vote goes to Maria.

I like girls what else can I say.


And thank you for starting this thread (to a person who started).


by the way does anybody know that surges in US do not damage computers (I have no idea why).
Power supply can be used on 120 or 220 volts could this be a reason?
and when you break Neutral wire and create 240 volt, most of the equipment burns except computer.

 

[prt_systems]

Quote from bali_survivor:

... Unfortunately your statement is incorrect since there will be a series / parallel circuit between the coil(s) and the capacitors used at the entry of the UPS's switching power supply.

Which has as a result that when the right high frequency impulse (read: spike) comes along the capacitor /coil circuit will nicely produce a very high voltage swing which is higher than the initial impulse.
.....
Maria

Physics checking in ...... This is true for the type of UPS systems you mention. In fact, it is usually better to not use any surge supression ahead of the UPS system - assuming the UPS system has certain characteristics - for exactly the issue you mention. I might also add that most people have no idea that low cost surge suppressors eventually wear out - and can fail in a most dramatic way - but give no indication to the user of this fact .....

 

[prt_systems]

Quote from balda:


...
And thank you for starting this thread (to a person who started).
...

If you search the archives you will find that this topic has been discussed ad nauseum .....

 

[winter]

Quote from MrProfit:

All modern printers have a special coding system to locate a source of a printout.

If you use your pinter, the copy has spots (like a bar code) which include date, time, serial number and model of a printer.

Same reasons.

Please provide proof of this statement or retract it. You seem to be vaguely referring to the somewhat recent discovery that SOME color laser manufacturers print a series of near-invisible yellow dots on every page that can be translated back to the printer serial number, date and time. This was done at the request of the US secret service. It is not every color laser printer and certainly not "all modern printers".

http://www.eff.org/news/archives/2005_10.php, see Secret Code in Color Printers Lets Government Track You

List of printers that do and do not have the technology:

http://www.eff.org/Privacy/printers/list.php

 

[winter]

Quote from jrlvnv:

I am still trying to figure out what he meant by the ALT-CONTROL-DELETE statement. Went where he said and I found nothing about it

Microsoft used to recommend (don't know if they still do) that you always hit ctrl-alt-delete to bring up the login screen. The reason is that it is possible for someone to write software that looks like the login screen and leave it running on your machine (if you forget to logoff/lock it), thus when you "login" to their software you just gave them your username/password. Apparently the OS does not allow any application to intercept ctrl-alt-delete so once you press those keys you know that the OS now has control, not some rogue app.

Edit, apparently they still do recommend it: http://support.microsoft.com/default.aspx?scid=kb;en-us;308226&sd=tech

Disabling the CTRL+ALT+DELETE sequence creates a "security hole." The CTRL+ALT+DELETE sequence can be read only by Windows, ensuring that the information in the ensuing logon dialog box can be read only by Windows. This can prevent rogue programs from gaining access to the computer.

 

[winter]

Quote from MrProfit:

You can read about that here:

http://www.rodaknet.com/rp_art_0224.htm

Don't believe everything you read on the internet.

The Dell keylogger conspiracy hoax
http://www.engadget.com/entry/1234000317047049/

Conspiracy theory of the day: Dell Laptop with built-in keylogger
http://www.boingboing.net/2005/06/16/conspiracy_theory_of.htm

Google for "laptop keyboard logger hoax" and read many many more....

 

[prt_systems]

Quote from winter:

Microsoft used to recommend (don't know if they still do) that you always hit ctrl-alt-delete to bring up the login screen. The reason is that it is possible for someone to write software that looks like the login screen and leave it running on your machine (if you forget to logoff/lock it), thus when you "login" to their software you just gave them your username/password. Apparently the OS does not allow any application to intercept ctrl-alt-delete so once you press those keys you know that the OS now has control, not some rogue app.

... or you can just run Linux .....

 

[prt_systems]

Quote from winter:

Please provide proof of this statement or retract it. You seem to be vaguely referring to the somewhat recent discovery that SOME color laser manufacturers print a series of near-invisible yellow dots on every page that can be translated back to the printer serial number, date and time. This was done at the request of the US secret service. It is not every color laser printer and certainly not "all modern printers".

...

You probably are not going to like this but .......
It is exrtemely easy to encode - in either a color or greyscale image - information that can not be detected by a human eye but can be detected by sampling the printed image.

Whether anyone has custom encoded these algorithms into ASICs is not known - nobody except perhaps the government has the resources to reverse engineer all the commercial printers ..... The algorithms would not appreciably slow down the printing process and the encoding detection levels are within the parameters of almost all modern printers including inkjet or laser......

 

[winter]

Quote from prt_systems:

You probably are not going to like this but .......
It is exrtemely easy to encode - in either a color or greyscale image - information that can not be detected by a human eye but can be detected by sampling the printed image.

Whether anyone has custom encoded these algorithms into ASICs is not known - nobody except perhaps the government has the resources to reverse engineer all the commercial printers ..... The algorithms would not appreciably slow down the printing process and the encoding detection levels are within the parameters of almost all modern printers including inkjet or laser......

The govt doesnt need to reverse engineer anything - they need to convince the printer manufacturers to insert these codes into their printers (or printer drivers) unless you are claiming that the govt convinced the asic manufacturers to supply chips that had been modified without the printer manufacturers knowledge.

In any case, without a shred of proof (which exists for color laser printers) it is all speculation and not based on any evidence. Since the OP also fell for the laptop keylogger hoax I'm going to err on the side of caution on this declaration and assume he again is misinformed.

 

[winter]

Quote from prt_systems:

... or you can just run Linux .....

Yes, because we all know its impossible to write a fake login screen program for Linux (rolls eyes)

http://www.linux.com/howtos/Secure-Programs-HOWTO/trusted-path.shtml