I really enjoy my n900, but i need to share my umts connection with my computer. It's easy to set up once you have usb networking up, but when i was about to do final step (the iptables postrouting) i had a very bad surprise.

It seems that iptables was left out of the distro

Is there any kind soul who compiled the netfilter module and iptables?

Yep, really a shame that iptables modules were left out! I'm keeping an eye on this thread:

http://talk.maemo.org/showthread.php?t=30916

to see if a working iptables setup appears.

it's different. IMO they only need some wifi driver hacking and hostapd.

I see i must compile these modules myself.

Not at all, if you read the thread, you'll see several people in there are talking about compiling iptables modules and binaries.

( To make a wifi hotspot, you need iptables to send people out to the net from an IP address on the cell network that can be routed back to )

Provisional solution:
Set up usb networking
ssh -ND 9050 192.168.2.14 &

Act as you are using tor
You have a socks proxy server on localhost:9050

BTW, writing from my eeepc using n900's UMTS connection.