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From "Alan Czajkowski" <Alan.Czajkow...@bmo.com>
Subject Re: IP Addresses on Subnets, etc.
Date Mon, 15 Dec 2003 16:38:42 GMT
mike,

ur still asking a technical question unrelated to tomcat, but here's the 
answer:

ok .. here's my understanding:
ur developing at home but the tomcat server is somewhere outside ur local 
network (somewhere on the internet)

request.getRemoteAddr() is returning the IP that ur ISP assigns to YOUR internet connection,
ur 
router handles the internet connectivity and therefore ur router is 
assigned this ip that the ISP gives u

whenever u "speak" to the outside world through ur router u r going 
THROUGH ur router, and since the router has built-in security the router 
"hides" ur internal network to the world on purpose, its called secutiry
in order to allow ONE of ur computers in ur local network to become 
"visible" to the outside world u need to goto ur router's setting and add 
that computer's local IP to the router's DMZ section on ur router settings
DMZ = De-Militarized Zone, meaning that it allows one of ur local 
computers to go in front of the firewall instead on hiding behind it (in 
theory - i've seem some routers that dont fully DMZ a computer which can 
sometimes be annoying)
this way request.getRemoteAddr() will return the IP that ur ISP gives u (which is NOT an alias,
it is an 
actual IP, it just happens to be an external IP that the internet uses to 
communicate with ur router and in tern with ur comps on ur network) and 
since u have put ur comp in the DMZ the IP that request.getRemoteAddr() returns will actually
point to that computer (that u have put on the DMZ)



Thanks,

Alan Czajkowski
-------------------------------------
Database Administrator
BMO Financial Group
Decision Support Services
3300 Bloor Street West
14th Floor, West Tower
Toronto, Ontario, M8X 2X2
Tel: 416.232.8736
-------------------------------------




webmaster <webmaster@michaelmcgrady.com>
15/12/2003 11:23 AM
Please respond to "Tomcat Users List"

 
        To:     "Tomcat Users List" <tomcat-user@jakarta.apache.org>
        cc: 
        Subject:        Re: IP Addresses on Subnets, etc.

Hi, Alan,

The folks in the know suggested this as the appropriate list.  I am not 
trying to obtain an ip address in order to access locally Tomcat, but to 
access Tomcat globally.  Therefore, the local subnet address will not 
help.  By a request object, I mean an http request object that I send to 
an 
outside computer and which, then, holds under request.getRemoteAddr()the 
ip 
address.  However, this appears to be an alias ip address which resolves 
to 
a remote host that is the isp address preceeded by a series of hexadecimal 

numbers.  Does that help?

Michael McGrady

At 07:57 AM 12/15/2003, you wrote:
>!!! u r posting a question about networking, this is the wrong place to
>post !!!
>
>but i will answer ur question anyway:
>
>u r behind a router, think of a router as two pieces, a piece that talks
>to the outside world (the internet) and a piece that allows your internal
>network to communicate with itself, between these two pieces is a 
firewall
>
>now, if ur on a pc network like me, the easiest way to figure out a
>computer's INTERNAL IP (because thats the ip u want) is to go to Start ->
>Run ... -> type: "cmd" then hit Enter -> type: "ping <computer-name>" 
then
>hit Enter
>this will reveal the computer's internal IP
>now, that piece on ur router that talks to the outside world u can
>consider it as a "computer" that has not only an internal IP but also an
>external one (the external IP is the one ur ISP assigns to u)
>
>i dont know what u mean by "request object" and i dont know what program 
u
>r using to talk to each of the computers on ur local network, but u
>shouldn't have to go outside of ur router and then back in to talk to a
>computer that is local on ur network
>
>
>Thanks,
>
>Alan Czajkowski
>-------------------------------------
>Database Administrator
>BMO Financial Group
>Decision Support Services
>3300 Bloor Street West
>14th Floor, West Tower
>Toronto, Ontario, M8X 2X2
>Tel: 416.232.8736
>-------------------------------------
>
>
>
>
>webmaster <webmaster@michaelmcgrady.com>
>15/12/2003 10:21 AM
>Please respond to "Tomcat Users List"
>
>
>         To:     tomcat-user@jakarta.apache.org
>         cc:
>         Subject:        IP Addresses on Subnets, etc.
>
>I want to use my home computer for some development on Tomcat.  I
>frequently use a laptop which is on a home combination wire and wireless
>router (one wireless and four wires).  How can I find out the ip address
>of
>each machine in the the network?  A call to the ip address of the laptop
>yields the subnet address 192.168.0.101, which, of course, is not the 
real
>
>ip address.  A determination by examining a request object sent from the
>laptop reveals an alias of some sort from the isp.  So, somewhere in
>between is the real ip address of the laptop.  How do I find that? 
Thanks.
>
>Michael McGrady
>
>
>
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