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Port Forwarding / Closing

Last response: in Networking
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July 20, 2005 5:31:44 PM

Basically I am thinking of forwarding one port on my Netgear RT314 Router (Default seems to be all closed) in order to speed up my peer sharing downloads (Azureus), according to the instructions I found here:
http://kbserver.netgear.com/kb_web_files/N101145.asp#RM...

However, before I attempt anything, I was wondering if there is a way (and how) to close that particular port again once I finish my file sharing session. (Or is the port perhaps automatically closed when I exit the file-sharing client?) How much of a risk is it to leave it open all the time?

Thanks for any responses

Ps. Also which one is the server IP adress they are refering to in the link, the 1 that both of my computers use or the 1 which is used to identify the particular computer I will be using file-sharing with?

I don't even believe in JEBUS!
Homer, you are on the flight to a remote island where you will be doing some missionary work.
SAVE ME JEBUS!!!!!!
July 20, 2005 6:39:03 PM

Depends on your router.

I have the standard linksys wired router at home. I can put in what's called Port Triggering.. when a certain apps requests a certain port, it opens up, closes when I'm finished.

By default, all ports coming into a router are closed. All ports going out are opened. The only way a port is opened from the outside of the router is if a request was sent from that router and it was waiting for something to come back on the same port. That's also the easiest way to hack through a home SOHO router, aside from guessing the password to the console.

You'll probably see a small to nothing increase in speed by opening that port up anyhow.

The local server being refered to is the PC you'll be using to access the program. So if you're running the App on computer A, put computer A's IP in there.
July 20, 2005 8:50:04 PM

Thanks for your response Riser,

Unfortunately, Netgear RT314 is a very old router so I am rather confident that it doesn't have Port Triggering.

However, from what I read in the BitTorrent forums (Azureus) using an open port can noticably increase the transfer speed, so I am thinking of giving it a try. (Especially since my speed now is merely 20kBps on a 700+kBps connection and I am getting NAT error on all my ports = I don't really have a choice)

So I guess my question is weather every port that can be manually forwarded can also be manually closed, which seems like common sense to me. I would usually not be so cautious and just assume that to be the case + experiment, but my roommate's computer B already has some confidential patient info so I really don't want to put him into any kind of jeopardy.

I found this great website that explains how to forward the port, so I am assuming that erasing the entries in port forward menu would close the port again, but I would love if somebody could confirm that. (Or at least assure me that there is SOME WAY to close a port again after it is open)

http://www.u.arizona.edu/~trw/games/example.htm#Netgear

Thanks again,

Ps. Also how can I find computer A's IP address? I remember I did it previously on a webpage, but it has been sooo long since I was computer literate :) 



I don't even believe in JEBUS!
Homer, you are on the flight to a remote island where you will be doing some missionary work.
SAVE ME JEBUS!!!!!!
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July 21, 2005 1:51:57 PM

Gotcha.

Routers by default close all ports. Port forwarding will open that port and send that information to the IP of which ever computer. If you remove that entry in the router, the port will be 'closed' to outside traffic again. It's fairly simple.. unless you tell it to be open, it's closed.

Bit Torrent creates a lot of connections and can overload your router which could cause a decrease in performance, but opening the ports does help in some cases from what I've seen.

To find out the IP address on 2000/XP computers, go to Start - type Run click ok - type IPCONFIG and hit enter.
Or
Go to Start - Control Panel - Network Connections - Double click on Local Area Network Connection - Support.

On older systems you can type "winipcfg" in the Run menu and it should bring up a box for you with the information in it.
July 21, 2005 3:39:22 PM

Thanks a lot riser,

You answered all my questions, I own you one :) 

I don't even believe in JEBUS!
Homer, you are on the flight to a remote island where you will be doing some missionary work.
SAVE ME JEBUS!!!!!!
!