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My Secure Dream laptop

The sort of "fast erasure" laptop you are dreaming about will probably not be either easier or harder to track down, than any commercially available "off the shelf" model you might buy at a computer dealer.

Consider the fact that most of the "volatility" of the laptop's data - the fact that it has no hard disk, that its RAM loses its content when the power goes off - makes no difference at all until *after* somebody has tracked you down and seized the laptop for inspection. At that point, they may be less able to find evidence that it was you who was posting hateful gibberish in a chat room... but they'll already have found you and will know who you are!

As to using phased-array antenna on your laptop - that might make it slightly harder for people to locate you by radio direction finding, if they're starting out at random locations. The same would be true of any directional antenna on your laptop. However, if they start RDF'ing for you from a location near the access point, having a directional or phased antenna on your laptop won't help a bit, since your antenna will be "beaming" its strongest signal right towards the access point. The same problem exists with using a maser (a highly impractical idea, by the way - they're big and clunky, and somebody would probably ask what you're doing pointing something that looks like a bazooka and has liquid-helium tanks at a coffee shop!)

How can they find which access point you're using? Pretty easy! In the situation you're thinking of (coffee shops), your postings will appear to originate from an IP address which belongs to the coffee shop itself. Either the coffee shop will have a range of routable IP addresses, one of which is temporarily assigned to your laptop (uncommon) or they'll have a single IP address, and your laptop's temporary "private network" address will be translated to theirs by their router.

In either case, your postings can be traced to the coffee shop. If you use a bunch of different coffee shops, you'll be revealing additional information about your location and habits. If somebody really wants to locate you, they can... every time you start posting, the access point's location can be determined. Post a few times from a few different locations, and somebody can correlate those times, and start looking at security-camera footage to see which individuals were near those locations at those times.

If you annoy people enough, they'll be able to find you.

--
Dave Platt                                    AE6EO
Friends of Jade Warrior home page:  http://www.radagast.org/jade-warrior
  I do _not_ wish to receive unsolicited commercial email, and I will
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Reply to
Dave Platt
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What is this "private network" address called? Is it different from the ARP table or the MAC address?

Reply to
GreenXenon

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In his case and by his reasoning, making him sit in the comfy chair would probably be more sever than mere waterboarding, and would enrage him and force him to say something naughty.

Or Green Xenon could be the next John Patrick Bedell.

Reply to
Greegor

It is kind of like ARP but is coming from DHCP. Only the local router=20 needs to know which address it assigned to your laptop.

Reply to
JosephKK

Most IP addresses are "globally unique" - that is, there can only be one active computer on the Internet with each specific IP address. Web servers, email servers, etc. which are intended to be reachable from any location on the Internet need to have a unique IP address and be "routable". You have to have a specific authorization to use such an address (e.g. you get one from your ISP, who was authorized to route and manage a whole block of these addresses).

Since there are only 2 billion IP (version 4) addresses possible (32 bits' worth), the Internet is running out of such addresses.

A small portion of the IP address space was set aside, many years ago, as "private, non-routable". Addresses of the form 192.168.xxx.yyy,

10.xxx.xxx.xxx, and some 172.xxx.yyy.zzz are of this type.

Anyone can set up a "private" network using these network numbers... you don't have to register for them in advance. As a result, there are many millions of small networks (e.g. homes and businesses) which use these network addresses. Any consumer-grade wireless access point/router is very probably set up to hand out these sorts of addresses to systems within its household network.

Because these addresses aren't unique and aren't registered, there's no way for a system using one of these to _directly_ connect to a system out on the Internet... there would be no way to route the response packets back to your laptop. Connections to the Internet must be made indirectly.

What usually happens is something called "network address translation" (NAT) or "IP masquerading". In effect, every time your laptop (on a private network) sends a packet out to the Internet, the access-point router automatically substitutes its own IP address (which is unique and routable) for the "private" IP address your laptop is using. The packets sent back in response by the site you're browsing reach the access-point router, and the router accepts the packet and then forwards it to your laptop. The router can do this for dozens of "private" IP addresses simultaneously. In effect, the router is acting as a "proxy" for your laptop.

So, from the point of view of systems out on the Internet, all of the web-surfing activity appears to originate from a single IP address - that of the access-point router - and this traffic can be traced back to that one system.

--
Dave Platt                                    AE6EO
Friends of Jade Warrior home page:  http://www.radagast.org/jade-warrior
  I do _not_ wish to receive unsolicited commercial email, and I will
     boycott any company which has the gall to send me such ads!
Reply to
Dave Platt

Not true. It just must not be globally visible. There are address=20 blocks set aside for "local" use. If you have a home router=20 (and most DSL modems are such) it issues local home addresses in the=20 reserved 192.168.*.* local user address space.

There are some large private networks on 10.168.*.* as well

The (ISP's) server must have a DNS translation address that is reachable.= =20 Not so much the home network.

Make that not quite 4 billion, and consider that even shoes will have=20 addresses in not too many years and the push to IPv6 is obvious.

Making my point for me.

This is also part of why the US is being obstinately slow to move to=20 IPv6. The other part is billions of deployed infrastructure; much of=20 which is not very programmable in the necessary ways.

More often the ISP address block, not really routers. More like = connection=20 point clusters.

Reply to
JosephKK

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