[LINK] technical question: security alert

[Steven Clark]

Chris Maltby wrote:
> In general there is no way to find out what IP address will be on your
> packets after all Network Address Translation (NAT) has occurred by the
> devices between your client and the Internet proper.
>   
you can. but it's not entirely trivial.
> Asking a site like "whatismyip.com.au" may be all you can do unless you
> have control of all the devices (including routers, satellite modems etc)
> that may be doing NAT, and you can ask them what their current external
> address might be. You could script either of these if necessary.
>
> One thing you can be sure of, is if ipconfig/ifconfig shows an address
> in the 10/8, 172.16/20 or 192.168/16 networks it's not your "real" IP.
>   
and to finish this explanation ...

... this is because those addresses [10.*.*.*, 8.*.*.*, 176.16.*.*, 
176.20.*.*, etc] are commonly assigned by routers to computers *inside* 
an intranet (aka behind the router's firewall). they are a real ip 
addresses, but are not generally used on the internet. there are a 
number of ip address blocks reserved for specific purposes [127.0.0.1 
being the most obvious, aka a pointer back to the machine the software 
is running on, aka 'home']

if you log into your router, it will tell you what ip address has been 
assigned or configured for it to talk to your isp. (what chris is 
implying to be your 'real' ip address ^_^)

some isps happily tell you what ip number they have (currently) assigned 
to your account. as i am an internode subscriber, i have a small tool in 
my (windows) taskbar called MUM that tells me the ip addresses assigned 
to my computer, my router (internal, as gateway) and internet (external 
address of my router).

[[you can think of an ip address like a postal address. your interent ip 
address is the mailing address that gets mail to your company (the 
router). the mailroom then sends parcels to the dept (gateway through 
the firewall - which sorts out mail to be accepted form rejected), who 
pass it on to your pidgeon-hole/office (your computer - which may have a 
firewall of it's own ...).]]

-- 
Steven R Clark, BSc(Hons) LLB/LP(Hons) /Flinders/, MACS, Barrister and 
Solicitor
PhD Candidate, Centre for Regulation and Market Analysis
School of Commerce, City West Campus, University of South Australia

/Finding a Balance between Privacy and National Security in Australia's 
ePassport System/