I'm not sure if this is an iphone issue, i think its more of a networking matter. but i believe some of you guys been there.

I've been trying to connect my iPhone to the internet through an wireless ad-hoc(computer to computer) connection hosted by my vista laptop which is connected using a LAN cable.

I've shared the LAN network.
I've set the TCP/IPv4 to obtain the IP&DNS addresses automatically on both the LAN and Wirless Network.
I've disabled my firewall.
I've made sure the internet is working on my laptop.

Now, the iPhone can see the connection, connects to it.
But then when i open safari and try to open 'google.com' or '72.14.207.99' i get
"safari could not open the page because the server stopped responding.."

any ideas?

i tried ad hoc-ing my iphone to my notebook...tried 2 days (about 10 hours in exact)...doesnt work at all. same situation like yours, it can detect and connect, but not more than 10 seconds and it'll disconnect again.

my advice: it doesnt work...get a wireless router

I'm sharing successful my broadband connection to iPhone via ad-hoc wireless with windiws xp. There are few simple steps to do this and this works for all systems.
1. You need share your intenet.
2. Set wireless adapters ip to static 192.168.0.1 and subnet 255.255.255.0
3. Set up ad-hoc network using WEP, open key (5 or 13 characters)with your own unique ssid.
4. In your iPhone enter ip configuratio(no need if you are using dhcp)- ip:192.168.0.2, subet:255.255.255.0, dnsfrom your isp, can be several separated by commas).
5. Connect from iPhone to your ad-hoc network, enter same key how in your computer.
6. If iPhone says 'cannot connect', then you should try again and again(iPhone can hold connection while you in settings menu and drop it when you push home button, so try to connect via ssh holding iPhone in setting menu). To fix this, you need edit some plist file. How to do this i wroted before.
Good luck!

on linux you also need install and run firestarter to share conection in easy way or configure route tables

http://www.zdziarski.com/iphone/

For those of you looking for a fully functional tethering solution, I've ported BIND 9.4.2 to iPhone. This allows you to service DNS when ad-hoc networking to your iPhone, so that tools without SOCKS support for DNS can use the connection. If you're just using Firefox for browsing, you won't need this as you can just set network.proxy.socks_remote_dns to true. Other applications, however, seem to lack a feature like this. The latest version of Leopard appears to also mangle the wireless connection when trying to set the iPhone as a SOCKS proxy using the networking config.

NOTE: Using a WEP key is what causes joining the network to fail, so unless it is necessary, just leave it an open network and you shouldn't have any problems.

@NerveGas not sure about it, because you can use WEP with key as without it, connection fails due to wrong timeouts issued by connecting to non apple hardware/software

I'm not sure if that was intended to be english or not... but the only time I've had any issued with the iPhone and WEP/WPA is connecting to an ad-hoc Leopard network. It works fine on my Linksys, and ad-hoc works fine without encryption.

Where in the iphone do you port these files to?

I had this problem:
I created ad-hoc WiFi network between my PC and iPod touch (i guess it's the same with iPhone)
I shared the wired internet connection and it worked for a while, but then it stopped. Sometimes it worked, sometimes it didn't.

What i did and it works now:

These are my iPod configurations:


This is the config of the WiFi card, that is connecting with my iPod:



The black fields are:
Default Gateway: The IP adress of my wired card, that gets the internet and is with shared net enabled. ('Start->Run->cmd-> ipconfig/all' and you will find it.)

The Prefered DNS server is the same IP
ALternate is OpenDNS, but i don't think it matters.

IMPORTANT:

How it works by me:

1) Open 'View available wireless networks' on my PC
2) Click connect to the ad-hoc network.
3) Enable the WiFi on my iPod.
4) Connect to the network.
(Only the first time) 1) Tap blue arrow and make the static configuration.
(Only the first time) 2) Disable all and do the steps 1-4 again.
5) WAIT in the 'WiFi Networks' menu on my iPod. Don't click the home button.
6) WAIT
7) Wait a bit more.
8) Hit the home button and KABOOOM - i have internet on my iPod.

I think it's very important to wait in the 'WiFi Networks' menu on the iPod, while PC and iPod comunicate. And then a little bit more.