Hotmail question.
 

Am I right in saying that the recipient of a Hotmail email can tell which individual computer the email came from by right clicking on the message and clicking on 'view message source'? Does the line in the code eg

X-Originating-IP: [86.159.19.47]

give the discrete computer it came from?

Not necessarily. All it tells you is the router address that passed the email out to the public internet.

The public IP address could be NATed to multiple PCs on the private side of the router / firewall.

For example, I have 3 PCs, a server, a laptop, a Wii and 2 DS devices on my home network - all sharing a single public IP address for internet access via the firewall / router that's connected to the cable modem.

For a corporate network, the number of devices on the private side of the firewall could be very large indeed.

Further, if the public IP address is obtained via DHCP - as most home connections are - then it may change periodically. So you might also need to know when the IP address was assigned to the physical MAC address of the cable / ADSL modem - and have access to the logs of the ISP that assigned the address.

SD

No, not if it is actually discreet as opposed to discrete, meaning separate.....

Thanks SD. How often do these public IP addresses change?

How often do you shut down the router / modem?

Impossible to say.

SD

So every time I power off the modem / router the IP address changes?

Not necessarily, as it depends on what your ISP does when it reassigns an IP address to you. Sometimes you always get the same one, sometimes it changes.

Hi Hobo - ...if you use Googlemail...you will be protected against anyone getting your ip's...And in any fact...I think it's only the police that can get your address by using your hotmail ip and asking the ISP for your details...
Hope it helps :)

My IP addresses (two houses) haven't changed in years. Some ISPs do, some don't.

If you look at the headers on an e-mail from me, you can tell which ISP it came through, and find my IP address. Not sure what you'd do with this information, because if you tried to connect to the IP, you'd find there's nothing there (see security thread).

Thanks for all this info, I was asking for two reasons, I want to send a completely anonymous email to a friend, who is very computer savvy, as part of an ongoing and elaborate "wind up" regarding a Council pay car park in his front garden, and also it occurred to me that if the IP address was recognisable, anybody could see if you were away from your normal address and know that your home was possibly unoccupied.

Hobo,
If he's computer savvy just pray he's not a PPRuNer (unknown to you) or you've just blown the gag!

Hobo, before you drop yourself in it, Goggle "who is" without the quotes. I believe you can also ping an IP address and find out if the PC is in use. In the old days ISPs never revealed an IP address owner unless the Police were involved. However the rules have changed and if the recipient feels harrassed or threatened by your e-mail I believe you have a right to the details of the sender within seven days. There are a number of IP address search methods available on the net. You could start with RIPE.org which is the EU registry of all EU IP addresses, it also gives you all the other Registers used abroad. Confidential e-mail?

Be very careful! If he doesn't see the funny side, you could find out a lot that you'd rather not have known.

The only way to get an anonymous e-mail is to register with someone like Googlemail - and even then, it can be traced if they want to. If I got a wind-up from a Google address, I wouldn't be foxed for a moment.

Most routers have an option not to respond to a ping request. Make sure it is set. You should also be able to operate in stealth mode so the router does not respond to port scans.
An easy way to check is to use ShieldsUp on the Gibson Research website