Real Life comparisons with technology and more day to day stuff

[synaesthesia]

Afternoon folks!

 

Idley wondering after using a couple of famed comparisons the other day, what other comparisons do techies use when explaining something technological to someone who wouldn't otherwise understand?

You know, the "water through a pipe" one for bandwidth/ping, the many car comparisons for cpu performance and what not.

 

I know there's some gems out there and thought it might be useful to see what others use I tend to try and make stuff up on the spot but that often goes wrong if the brain is in the wrong place!

[chinesewhispers]

I recently used something similar to:

 

'It's like the number has fallen off your front door, so the postman doesn't know your address, or where you are, so you aren't getting your post, I'll have to make sure we put the number back up'

 

as an analogy for the machine not getting an IP address and not being able to log on/get access to systems.

 

The teacher appreciated that. Subsequently, having swapped out the PC, it required the display frequency changing to stop flicker on the projector, I told her that the postman now knew where she was, but had mistakenly delivered some jelly!

[torledo]

Afternoon folks!

 

You know, the "water through a pipe"

 

 

isn't that normally used to explain the difference between voltage and current.

[RabbieBurns]

isn't that normally used to explain the difference between voltage and current.

 

resistance was it not?

[pete]

"CPU cache is what you can hold in your hands, RAM is what you can fit on your desk, Hard disk space is the cupboard over there."

[maniac]

The really obvious one is using a filing cabinet to explain how folders work in windows - (oh yes there are still people who regularly use computers that don't understand the concepts of folders.)

[Ric_]

The really obvious one is using a filing cabinet to explain how folders work in windows - (oh yes there are still people who regularly use computers that don't understand the concepts of folders.)

 

You mean directories

[maniac]

You mean directories

 

Hey, it says 'Folder' when you create a new one doesn't it

[deanc]

not if you use mkdir

[torledo]

The really obvious one is using a filing cabinet to explain how folders work in windows - (oh yes there are still people who regularly use computers that don't understand the concepts of folders.)

 

how would you go about explaining *nix partitions to folk such as that ?

[synaesthesia]

how would you go about explaining *nix partitions to folk such as that ?

 

"Imagine if you had a schizophrenic assistant with OCD...."

 

But then again, thankfully, that's not something generally people would/should have to explain too much

[tom_newton]

how would you go about explaining *nix partitions to folk such as that ?

 

Different offices?

 

A colleague used a saxon village analogy to explain a firewall once. I believe it is still on the internal SmoothWiki somewhere. I will see if I can get Darren to post it on monday

[deanc]

Easy,

 

each drawer in the filing cabinet is either a drawer full of files or a gateway to another place similar to Narnia, only instead of Narnia it is actually another filing cabinet.

[datalas]

Introduction

 

The first question involved in any protracted discussion of a topic is how to present the concepts involved within in such a way as that they might be understood by people who are not already aware of the ins and outs of the problem, this is a common flaw with many discussions of a technical nature, documentation often serving more as an aide memoir to the developer or author than as a serious attempt at conveying knowledge.

 

For the purpose of this discussion we are going to deal with pretty much all of the concepts of networking via a humble medieval fellow called "Harold", All other aspects will be shown to relate to Harold, his family, household and medieval world, it also allows for us to sit around and contemplate a simpler time, a time before keyboards and office jobs.

 

Simple Networking

 

Harold currently owns a farmstead, so he's quite possibly a Knight of some description. Most people own farmsteads and these are generally connected via a variety of means to other farmsteads. They can be reached from another farmstead via one of two methods, walking happily overland (which is essentially along a local network or switch) or they can traverse the big wide oceans that are the Internet.

 

Basic Protections

 

Harold, being a rather cautious fellow, as well he might be in these perilous times has decided to protect himself from the outside world. Granted that the "Internet" is already patrolled by the local authorities, (his ISP) but he doesn't particularly trust his neighbours. So, he builds a nice large wall around his farmstead. This is a Firewall. It keeps people out, it also potentially keeps people in, but in it's current state you can just jump over the wall if you live with Harold.

 

Now, This is all fine and dandy, but not being a gibbering idiot Harold has taken the sensible precaution of fitting a door to his wall. This "Door" is actually an overly complicated affair which resembles a waterside dock than it does a traditional "door", and so it might be best to assume that Harold's property overlooks a small lake and that he's chosen to open the docks to the outside world. This lake is in turn connected via a canal to the Ocean, this is the ISP's connection to the internet. This may be monitored in some way, or not...

 

This dock has a particular address (Harold's house) and has a number of docking points along it, these are in terms of networking synonymous with an "IP address", and a "port". To deliver anything to Harold, you would need to travel to a particular "port" at his address. Note that these ports can be temporarily (or deliberately) out of service, presumably by putting a bag over the top of the pole you need to tie yourself onto.

 

Outbound traffic is unrestricted at the moment, that is that Harold (or anyone within his household) can merrily wander down to the docks, choose a boat and launch it from a particular port. Their return journey is accepted because they were seen to leave.

 

Hardware or Software Firewalls

 

There is a lot of discussion in the world about the nature of a "hardware" or a "software" firewall, which is quite ironic when you consider that any and every firewall is both. In the case of Harold, his wall is neither brick, nor is it mortar exclusively. This discussion is actually about the placement of the software that produces the "wall" within the system.

 

This is best described as being one of two things.

 

* A dedicated piece of hardware which provides firewalling capabilities as a "black box"

* A piece of software that runs on a computer and provides firewalling locally to the one machine.

 

Sadly the arguments as to how these work are very complicated, however the dockyard that Harold runs is basically the "TCP/IP" stack, that is the bit of software that controls how the computer communicates with the outside world. In a hardware firewall the wall sits immediately up the road from the docks, the farmstead itself is connected to the docks only by going through the wall. In a software firewall, since the docks are now part of the farmstead the "wall" is erected around the farmstead itself. A minor distinction perhaps, however should a barbarian or similar overrun the docks entirely they would then be able to run around the land outside the wall, raping, pillaging, stealing cattle and the things that barbarians are want to do.

 

Network Address Translation (NAT)

 

So far Harold has set up his little dockyard, and has built his wall, he's even go so far as to start to decorate the inside with an array of pleasing tapestries. He's also just built a little granny flat to accommodate his mother in law.

 

currently the dockyard hasn't got many ports open, and those that are are just delivered to a similarly numbered pigeon hole at Harold's house. Now however, he has two addresses within his farmstead... hmm, what to do.

 

Harold's solution is ingenious, well, it isn't... he hires a harbour master. The harbour master sits at the docks and when someone arrives (connects) at a particular "port" he asks them for the address and port they were trying to get to, "Flat 25 Harold's House", the harbour master then recognises that anyone arriving for Flat 25 actually means the granny flat, and therefor writes the "new" address on the top of the sailors map, and lets him past the firewall.

 

This is "Network Address Translation", and provides the simplest form of network security. That is "Security by Obscurity", there has been little validation of the sailor at this point, only that he arrived at a known port at a known address. He could still be harbouring any number of nasties, drugs, rock and roll, syphilis, the plague, a large wooden horse with adequate room for a complete army and toilet facilities, the harbour master being a bit daft, doesn't check any of these things.

 

Aliasing

 

Harold, being an enterprising sort has now decided that he wants to branch out a little, and has set up his own business (Harold's dairies) where he will sell the wares of his farm (with the unmutilated cattle, thanks to his firewall). Now, he doesn't want to do this via the Address "Harold's House", since, well, he'd rather keep that private.

 

He therefore sets up a "PO Box" address on the lake, and instructs his harbour master to redirect traffic accordingly. This doesn't even have to be using the same set of rules for Harold's house, so that's nice.

 

DeMilitarized Zones (DMZ)

 

As has already been explained, Harold is a cautious fellow, and he's not entirely keen on people rampaging around his farmstead merely because they are visiting the farm shop. Hence he builds another wall inside his farmstead, and updates the harbour master with this information. Ergo, people going to his house may do so, people going to the shop are likewise free to do as they wish, however, people who pretend to go to the shop and are intending on looking around the farm will find themselves on the business end of an impressive array of brickwork.

 

Intrusion Detection

 

As said before, the harbour master is a bit of a daft sort, but he's at least cheap. Whilst he provides a moderate amount of security, and he's certainly burly enough to dissuade anyone who tries to get past him, anyone who knows where they are going is free to pass where they want.

 

Harold then installs a CCTV system in the harbour masters office. Where a medieval knight gets a CCTV system from is perhaps a better question, but we shall just assume that CCTV stands for "Cute Cousin Taking notes Vigorously" and we should get away with it.

 

The Cousin (who actually looks a bit like a pig) will take notes about everyone that wanders through the office and study them for anything that looks suspicious, such as the aforementioned equine sculpture. When she sees something that doesn't look quite right she notes it in her journal so that should anything untoward occur they know where the likely suspects came from, and were going.

 

Virtual Private Networks

 

Harold's business is doing well, so well in fact that he has to hire an accountant. Now, being a farming chap Harold doesn't have an accountant living with him, and quite often takes comfort in the knowledge that the nearest one is actually several hundred miles away down the coast.

 

However, this presents a problem. How do you actually get letters to and from the accountant ?

 

Well, there is an obvious solution, which is just to put them on a boat and let them make their own way there, but this is fraught with danger. The letters could be intercepted, modified, spied upon, used by his competitors and who knows what else.

 

So, what to do ? There are two real solutions which present themselves, the first is to build a huge canal directly from Harold to his accountant, over the mountains etc. This would be a direct line (or leased line) and would be immune to pirates on the Internet doing things that Harold would rather they didn't do with his trade secrets. This however is a logistical nightmare, and financially out of Harold's league.

 

So, Harold invests in a pair of decoder rings he found in a packet of cornflakes, these are some form of pre-shared information, either a pre-shared key, or complicated certificate based scheme, either way they allow Harold to encode his message in a way that makes it undecipherable to anyone without that information. This message is then sent in it's encoded form (he wrote it in welsh) to the accountant who then translates it back to it's original form. Thus all communication can be done via the Internet, without fear of the messages being intercepted, as they wouldn't make sense.

[torledo]

So, Harold invests in a pair of decoder rings he found in a packet of cornflakes, these are some form of pre-shared information, either a pre-shared key, or complicated certificate based scheme, either way they allow Harold to encode his message in a way that makes it undecipherable to anyone without that information.

 

i'm sorry, i was with you up until this bit. Any chance you can reset my password, and we can forget this conversation ever happened.

[powdarrmonkey]

Recipes and ingredients for why PowerPoint doesn't play video you left on your home computer.

[p858snake]

how would you go about explaining *nix partitions to folk such as that ?

 

without explaining symlinks:

 

Root (\) is the shell of the filing cabinet, each partition is a draw in the cabinet and inside that draw is the directories (folders for the filing cabinet) it's holds.

[powdarrmonkey]

without explaining symlinks:

 

Root (\) is the shell of the filing cabinet, each partition is a draw in the cabinet and inside that draw is the directories (folders for the filing cabinet) it's holds.

 

Erm.. what if you mount (as I do, so not merely hypothetical) a ramdisk to /var/cache/pbuilder/build/cows? Then you have a folder holding a drawer, and your analogy breaks down as your filing cabinet implodes

 

Much better to reverse it and say your partitions are your folders, and your directories are your drawers. Then you just have the challenge of explaining that sometimes folders are spread across many drawers..

 

And this is before you add LVM to the mix of course