Re: Determine My IP Address
Re: Determine My IP Address
- Subject: Re: Determine My IP Address
- From: Les Vogel <email@hidden>
- Date: Tue, 25 Apr 2006 15:34:52 -1000
And the answer is....
DON'T tell the other client. Let the other client get the info for
themselves from their own network stack.
Sending your own IP address over the network as part of your payload
is ALWAYS WRONG.
On Apr 23, 2006, at 11:43 PM, Quinn wrote:
[1] Well, there are always circumstances where things like this
fail. If there's a NAT between you and the remote host, for
example. Or if the firewall is blocking incoming connections to
your server port. Still, it's a good place to start.
I agree with Peter, it's best not to include an IP address or ports
in your payload. Some protocol's require it, and some NAT
implementations fix them up. FTP and RTSP come to mind.
While this isn't necessarily reliable, you can look at your IP
address to see if it's in a "local" range to help you determine if
you are on a NAT system. (192.168.0.0/16, 172.16.0.0/12, 10.0.0.0/8,
and a few others http://www.rfc-editor.org/rfc/rfc1918.txt ) Some
well meaning sysAdmin's just make this stuff up, so this technique
won't always work. If it's in one of these ranges, you are probably
NAT'd, if the other's IP address is in the same range, you can just
report your "private" address, if it's not, you can do a trace route
(RFC1393) and look for a router that's got a public IP address. That
might be you (alas no guarantee). There are some services that will
report to you your "real" IP address, you might try to google for it,
I can't recall what it's called. (It's been a while since I thought
about these kinds of issues). An important point, is that when you
are behind a NAT'ed environment, your port may change as well, it's
hard to tell. Also, a SysAdmin (person who setup the Router) may
have setup a port map. I would suggest that you allow your users
someway to specify (if you can't figure it out) what "real" IP
address they have. (allow a port # as well)
-
Les Vogel
P.O. Box 598 AIM: lesv3 Jabber: email@hidden
Kihei, HI 96753-0598 Skype: lvogel3 blog: http://www.angeltech.com/
blog.html
email@hidden
(808) 870-0418
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