iptables and masquerading

[DuDu <dudu@dudu.prout.be>]

Hello,

sorry for the basic question, but after a storm my gateway was rebooted.
I didn't put basic rules in a script and after reboot no internet on my
local network.

be sur i don't want a secure network, just a way to world through my gateway :
- /proc/sys/net/ipv4/ip_forward at 1
- iptables -t nat -A POSTROUTING -s local -j MASQUERADE

Don't work but all is on accept ...

I don't understand ...

David Dumortier
PS : sorry for english, bad mail (use mail on gateway), and basic question.
PS 2 : thank's for any advice (can be private for this)
PS 3 : have a good access to gateway from localnet and good access to world from gateway.