I just installed my modem under redhat8.0 and everything works well but I would like to share this connection with my windows machine.
I've tried to search the forums but find a few too complicated things about that

is there a simple way to share this connection? (I've tried with firestarter without success and the windows machine is properly configured)

any help appreciated =)

Assuming you have a basic working network.

Try:
# Save your current iptables setup
service iptables save
# Remove any current rules
iptables -F
# Enable forwarding of packets from eth0 to ppp0
iptables -A FORWARD -i eth0 -o ppp0 -m state --state RELATED,ESTABLISHED -j ACCEPT
# Enable IP forwarding
echo 1 > /proc/sys/net/ipv4/ip_forward

Then set the Gateway ip on the windows machine to be the same as the linux box. Also set the DNS ip on the windows box to being whatever your isp uses.

If this works then you can set about making the changes more permenant - no reboot on the linux box should be neccessary bu the windows machine may need to be restarted in order for the gateway to change.

If it doesn't work post any error messages and the output from these on linux:
iptables -L
route
cat /proc/sys/net/ipv4/ip_forward

Then on Windows:
route print

well, I tried that but when I does it ; my lan doesn't work anymore because I'm unable to access the windows machine with vncviewer and I get Destination Host Unreachable when I try to ping it

cat /proc/sys/net/ipv4/ip_forward
0
--> which is strange =)
_________________________________________________________
./iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination
__________________________________________________________
./route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
slc1-tc.xmissio * 255.255.255.255 UH 0 0 0 ppp0
192.168.0.0 * 255.255.255.0 U 0 0 0 eth0
127.0.0.0 * 255.0.0.0 U 0 0 0 lo
default slc1-tc.xmissio 0.0.0.0 UG 0 0 0 ppp0


I really don't think that the problem is coming from the windows machine.

Do you have any idea? and how can I cancel those changes in order to make the lan work again without formating my computer again :\

thx =)

All you did was flush your firewall rules - if you saved them like I suggeseted then you can just:
iptables -F
service iptables restart

I don't know why the ip_forward was lost - the same with the iptables unless you rebooted the computer.

Did you get any errors when you ran the commands?

ok, actually I did reboot the computer... now I did everything again without rebooting, the lan works again (I don't know why =)) but I still cannot browse a website on the windows machine

____________________
./iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination

Chain FORWARD (policy ACCEPT)
target prot opt source destination
ACCEPT all -- anywhere anywhere state RELATED,ESTABLISHED

Chain OUTPUT (policy ACCEPT)
target prot opt source destination
_________________________
./route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
slc1-tc.xmissio * 255.255.255.255 UH 0 0 0 ppp0
192.168.0.0 * 255.255.255.0 U 0 0 0 eth0
127.0.0.0 * 255.0.0.0 U 0 0 0 lo
default slc1-tc.xmissio 0.0.0.0 UG 0 0 0 ppp0
_______________________
cat /proc/sys/net/ipv4/ip_forward
1
_________________________
C:\>route print
===========================================================================
Interface List
0x1 ........................... MS TCP Loopback interface
0x1000003 ...00 50 ba bc f6 a4 ...... Realtek RTL8029(AS) Ethernet Adapt
===========================================================================
===========================================================================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 192.168.0.2 192.168.0.3 1
127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
192.168.0.0 255.255.255.0 192.168.0.3 192.168.0.3 1
192.168.0.3 255.255.255.255 127.0.0.1 127.0.0.1 1
192.168.0.255 255.255.255.255 192.168.0.3 192.168.0.3 1
224.0.0.0 224.0.0.0 192.168.0.3 192.168.0.3 1
255.255.255.255 255.255.255.255 192.168.0.3 192.168.0.3 1
Default Gateway: 192.168.0.2
===========================================================================
Persistent Routes:
None




(btw the ip of redhat is 192.168.0.2 and the one of the windows machine is 192.168.0.3 so that you don't get confused)

I hope I'm not too annoying :\ I really appreciate your help

I managed to solve my problem using skyfire-1.0.1 which is a little script that asks you a few questions and configures iptables for you

wonderful thx david_ross, after my exams I'll try to understand this iptable thing, but for the moment this script is perfect =)

linux rocks