12 replies to this topic

[Mikorist]

Do you keep your computer running 24/7/365 ?

My answer is a resounding "yes, I do."


My Desktop + My Ubuntu + PC all run 24 hours per day, 7 days a week — 24/7.

With Linux, I don’t have to worry about a Virus-Malware-Trojan army running my computer 24/7.

Linux is freedom from antivirus crap...

[was_jaclaz]

FYI,
my PC has run 24/7/365 since march 2003 till a few days ago, when during a storm a lightninh made it's way (this was the second time) through the network ground and fried the motherboard.
First time it fried just the network card, and with a PCI add-on card I got it working another couple of years, this time something in the motherboard went beserk.

I run Win2K.

I have another PC running NT 4.00 that is on 24/7/365 since April 2001.

What was the point?

jaclaz

[Brito]

a storm a lightning made it's way (this was the second time) through the network ground and fried the motherboard.

Wow.. Is this possible to happen?

I sometimes wondered how machines got fried even when connected to UPS devices, this is nice to know.

------

It's rare to see any of my home computers running for longer than the usual daytime work hours - only the usual servers at the workplace function non-stop but sometimes the power fails and everything shuts down..

--

I run Win2K.

How do you install the security patches, service packs and such without a reboot?

Or probably you need to upgrade your windows version to support the latest viruses.

(I know you probably don't update since 2003.. )

[pscEx]

What was the point?

I agree to Jaclaz with one difference:

I allow my computer to sleep while I sleep. That saves some energy.

I work with XP and allow Billy the Door to implement every update he thinks that it is necessary.

My way of life:

• Try a new app in a VM first
• Disallow scripts in Firefox
• (I did not need until now to restore after a crash) daily automatic backup

Peter

[MedEvil]

Do you keep your computer running 24/7/365 ?

My answer is a resounding "yes, I do."

Big deal, who doesn't?

Linux is freedom from antivirus crap...

Antivirus crap is not installed to protect the computer from trojans, virii and therelike. It's installed to protect the computer from moron users.
And with Linux getting easier to use, you will get those kinds of users too in larger numbers!

[pscEx]

Antivirus crap is not installed to protect the computer from trojans, virii and therelike. It's installed to protect the computer from moron users.
And with Linux getting easier to use, you will get those kinds of users too in larger numbers!

I have a similar feeling with my currently rather secure FireFox.

Peter

[fxscrpt]

maybe Ubuntu checks for Security Updates infrequently.
https://help.ubuntu....SecurityUpdates

Peter

[Brito]

I allow my computer to sleep while I sleep. That saves some energy.

I agree with the power saving habits - especially when it's a concern to your own pocket.

At my house all electric plug have switches to power off without need to pull the plug from the wall.

------------

Antivirus crap is not installed to protect the computer from trojans, virii and therelike. It's installed to protect the computer from moron users.
And with Linux getting easier to use, you will get those kinds of users too in larger numbers!

Yep, this is unfortunately true.

It's far easier to install programs in linux than ever before and it shouldn't take long until it becomes a target like windows as ubuntu and such grow popular.

No protection against those users who blindly type the admin password without knowing (or caring) if the program they're installing is trustworthy..

[Mikorist]

What was the point?

jaclaz

This is the point - your opinion - your experience

Big deal, who doesn't?


Antivirus crap is not installed to protect the computer from trojans, virii and therelike. It's installed to protect the computer from moron users.
And with Linux getting easier to use, you will get those kinds of users too in larger numbers!

That is why some users have problems updating ZoneAlarm !

maybe Ubuntu checks for Security Updates infrequently.
https://help.ubuntu....SecurityUpdates

Peter

That is true... It updates itself automatically and it's free - how cool is that?

Directly quoted:. The Ubuntu Promise. Ubuntu will always be free of charge, including enterprise releases and security updates. ...

[was_jaclaz]

@Nuno
@psc

Well, mine is an environment which is actually open 24/7/365, and of course there are re-boots from time to time, for maintenance, installing whatever needs a reboot, etc.

Usually, there are stretches of two to three months without need for a reboot, I seem to remember that longer stretch between reboots was six or seven months.

The problem with the lightnings is unfortunately unavoidable, but is not as common as it may sound.

We have a (very good) grounding of the electrical system, including a Faraday cage around the building.

The problem comes from the fact that part of the hardware (PC's and telephone boxes/PBX) is actually grounded, whilst most of it (router, network hubs, printers, telephones) is not. Don't know the exact English term, it should correspond to "double insulated" or "Class 2", meaning that the AC plugs have no earthing.

What has happened (twice in the last four years) is supposedly (this is the best "logical" explanation we could come out with, though not really and fully "logical") the following:
1) a number of lightnings, during an exceptionally intense storm, strike VERY near, or even hit the Faraday cage
2) the amount of "incoming" electricity is enough to raise the theoretical "0" (zero) level of "ground" to something bigger than the 5 Volts that most electronics are designed for, probably something in the range 20 to 50 V
3) this "power" find it's way inside one of the grounded apparata, and then goes into either the telephone or network, where it finds no way to "escape"
4) damages (if any) are semi-random, like:

(the one before last):
1) a printer connected to the telephone network
2) three out of the 24 modules of the telephone PBX + it's CPU
3) two ports of a hub
4) one network card inside a PC (NOT connected to either of the two ports above)
5) three or four fire alarm sensors
6) the display of one of the telephones

(I have put a couple of optical disconnectors to better separate the telephone lines after the above)

(last one)
1) a motherboard and NIC
2) two fire alarm sensors
3) two of the four power supplies of the PBX

Please note that ALL the damages happened on the "low voltage part" of electronics, everything meant to be working at 240 V AC, even the "high voltage part" of the power supplies that were fried, were untouched on the 240 V AC side, and "fried" on the +5 V DC side.

jaclaz

[Mikorist]

Please note that ALL the damages happened on the "low voltage part" of electronics, everything meant to be working at 240 V AC, even the "high voltage part" of the power supplies that were fried, were untouched on the 240 V AC side, and "fried" on the +5 V DC side.

jaclaz

Every computer I opened contains the same protection components: two blue 470 V varistors. One between neutral and ground and one between phase and ground:


The role of such a varistor is to become a shortcut should the tension between its two wires exceed 470 Volts. So the tension between the phase wire and the ground wire never can exceed +470 V or -470 V. As well as between the neutral wire and the ground wire. Any tension on the neutral or phase wire that would be lower than -470 V or higher than +470 V, whatever the source of that tension pike, whether it be a lightning strike or a condensator discharge, will be drained to the ground by the varistors. The current they can let through can be very high provided it has a short duration. The maximum tension present between 240 V AC normal mains wires is 339 V. So a 470 V varistor protection means the tension is not allowed to go 40% higher than the maximum normal value.

At first glance the protection seems perfect. Yet is is not. Because what matters for an electronic device power source is the voltage between the neutral and the phase. If the tension difference between neutral and ground will be held to a maximum of 470 V and the tension difference between ground and phase is held to a maximum of 470 V too, this means the tension difference between neutral and phase can rise up to 2 x 470 = 940 V. For example suppose at a given moment the phase tension rises to its normal maximum of +310 V. A lightning strikes and would tend to make the neutral wire go down to a tension of -10,000 V. The varistor between neutral and ground trades in and cuts the neutral wire tension back to a mere -470 V. This makes the tension between the phase wire and the neutral wire be 310 - -470 = 780 V. That is 150% higher than the maximum normal value! A though device will withstand such a tension pike. Yet a not a sensitive or fragile device.

Something needs to be done to force the tension between phase and neutral not to exceed say 470 V. The solution is simply to solder a third 470 V varistor between the neutral and phase wires:


Such a theory has to be tried out. I didn't want to wait for a lightning strike so I used an old VGA computer display that makes my computer crash. Sometimes, when I switch that old display on, the ATX power source of my computer goes into protection and suddenly halts the computer. This is due to tension peaks on the mains produced by the old VGA monitor being switched on. The two varistors my computer power source contains are not sufficient to protect the power source. Actually they do protect but not enough to prevent the power sources chooses to switch off. So I put a varistor between the neutral and phase wires of my computer and tried to switch the old VGA display on and off many times. The computer power source never switched off. So clearly a third varistor is a good thing.

Maybe there are technical reasons not to do so. But I did not think or hear of any serious one till now. A kind reader informs me a reason can be in some countries the neutral is wired to the ground, so the third varistor would be useless.

Beware:

* Electric wires colors and names displayed in this page may not apply to your country.
* Do not solder or try out anything on mains wire if you are not fully qualified. This could result in damage to your equipment, house fire, injury or death.
* Many components look like a varistor but are not a varistor. And varistors are made for a wide range of tensions. So unless you really know about electronics you will probably not be able to be sure you are holding a real 470 V varistor.

My computer system is now well protected against lightning strikes. Both the monitor, printer and computer are protected. But when I hear thunder I tend to unplug the modem. Because the path from the mains towards the phone line can be a way for a high current lightning strike. I'm not sure about this but I prefer not to take any risk. So I unplug the modem. Following the same reasoning I unplug my computer from the local network. Because there could be a lightning path between the networked computers. Good network and modem devices contain protections against lightning. But who knows. I could not check them to be 100% effective and I'm not ready to risk my computer to test this out. Finally, I make sure the computer, monitor and printer are on the same mains wall plug. That way there is no lightning path between two different wall plugs (for example should the computer be on one wall plug and the monitor on another wall plug situated another side of the room).


from: http://www.4p8.com/e...ur/protect.html

Anti Surge and Lightning Protection for your Satellite and all other appliances (DVD, VCR, Computer etc. 6 Outlets) Plus protection for the aerial connection and telephone.
http://www.englishtv...Accessories.htm

[was_jaclaz]

To maybe clear things a bit:

There is NO conceivable apparatus capable of "preventing" a direct hit of a lightning.

We are talking of several thousands of Volts, commonly used reference give in DRY air a safety clearance to avoid discharge (arc) at the rate of 1 cm every 1000 V.

In other words a 10.000 Volts tension can discharge in around 6 cm (and thus the safety measure is to have 10 cm clearance).

So a ligthning hit will easily "jump" over the varistors, as the poles are around 1.5 cm apart.

Devices or circuits as the above described work VERY well for power surges ONLY, that are in a range well below 1.000 Volts.

jaclaz

[Mikorist]

To maybe clear things a bit:

There is NO conceivable apparatus capable of "preventing" a direct hit of a lightning.

jaclaz

Every explosion sounded like a direct hit of a lightning but
it really would have to be an extremely close or direct hit to hurt.