Hello,

Sorry for the non-Japanese-related question.
I've been wondering for years how to do this and there seem to be a lot of computer savvy people here.

I am connected to the internet through a Buffalo AirStation router and an NTT ADSL modem. As a result, my PC does not have a globally accessible IP address, but only a local IP address, generated by the ADSL modem.

So my question is, if I set up a server on my PC, how can I make it so that people can connect to it via the internet? I know it's probably something in the modem's settings, but I've looked at them all and I'm stumped.

Can anyone try to point me in the right direction?

your router is probably assigned an internet IP address by the modem and then your computer is assigned a local IP from the router (for example 192.168.1.1)

you can find your router's IP address and turn on port forwarding in the router's option menu. You can forward traffic on the correct port to the local IP address of your compy.

That said, your ISP could have other firewall junk on their side of things and your IP address assigned from the ISP could be dynamically assigned, so the IP could be changing every now and then.

That's my guess anyways. I'm not a super 1337 network admin, so it's probably all wrong ^__^

Strangely enough, it's my modem that's giving out the local IP addresses even though there's a router in between, and it was doing this before I even attached the router. I'll see if I can get it to stop that, but it's not looking hopefull.

Ideally, this is how you'd do it.

1) Find out what port your server program is listening on.
2) Log into the web-interface on your router
3) Find a section titled 'NAT' or 'Port Forwarding' or something... (it could be almost anything...)
4) Forward the listen port to your PC's IP.
5) If it asks, forward both TCP and UDP traffic.

But I see you've mentioned that the modem itself is handing out local IP addresses. That's kinda unusual, the job of the modem is usually just to provide connectivity to the greater telecomms network, ie, non-IP data. Just to confirm, if you connect your PC directly to the modem (skipping the router) do you get an IP address within these ranges... ?

10.0.0.0 - 10.255.255.255
172.16.0.0 - 172.31.255.255
192.168.0.0 - 192.168.255.255

If not, then you should have a genuine intarweb IP and assuming your ISP doesn't filter data, all connections should come through OK. If the address is within those ranges, then you'll need to log into the modem somehow and see if you can do any port forwarding on it.

I've encountered NTT setups where a 'sharing box' is installed in the apartment building, and each user is connected to that box - effectively giving you zero chance of opening ports up to the outside world. There is a chance that's what you're encountering here.

@aircawn

Yes, if I connect my PC directly to the modem, the PC's IP is 192.168.1.2, and the router's local IP is 192.168.1.1. There's even an option to change the modem's LAN IP address, and if I change it to 133.7.35.6, my PC's IP address becomes 133.7.35.7. Stays that way if I add the router into the mix.

I've just noticed that in the modem's basic settings page, the top item is "Operation Mode" and I can select from "NAT Router" (default) and "Bridge." If I change it to bridge, the PPP connection stops working.

There is a setting category for "Static NAT Settings," which I've tried using in the past but will give it another try. Will let you know if I have any luck.

Woah, it worked. And it was really easy. Thanks for pointing me in the right direction.

Sweet.

resolve Wrote:I've encountered NTT setups where a 'sharing box' is installed in the apartment building, and each user is connected to that box - effectively giving you zero chance of opening ports up to the outside world.

That really sucks... :/