I have 2 computers.
One is connecting to the internet through gate 192.168.1.1.
It is also supposed to forward connection to and from the second computer.

I wanted all interfaces to have IP starting with 192.168.1.
Ideally like this:

PC0 PC1 PC2
gate eth0 eth1 eth0
192.168.1.1 192.168.1.31 192.168.1.32 192.168.1.33


I used the following commands to do this.

echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -o eth0 -s 192.168.1.33 -j SNAT --to 192.168.1.31

unfortunately it doesn't work.

I know that when I change:
192.168.1.32 in to 192.168.0.32
and
192.168.1.33 in to 192.168.0.33

routing is just fine

Is there any way to have all IP starting with 192.168.1. ??? (the gateway accepts only this kind of IP)
Otherwise I have to change IP of the second computer when I connect to the gateway directly or when I run WindowXP on the PC1 which is using bridging for sharing connection.

Andrzej

once again schame of of my network. (previous posting is not clear)

PC0 PC1 PC2
gate eth0 eth1 eth0
192.168.1.1 192.168.1.31 192.168.1.32 192.168.1.33

sorry. once again.

PC0______________________PC1______________________PC2
gate_______________eth0___________eth1______________eth0
192.168.1.1______192.168.1.31____192.168.1.32_________192.168.1.33

Anyone

anyone??

when you configure your iptables to route the network are you putting 192.168.0.0/24 or 192.168.1.0/24.

If you are using a 24 bit subnet mask, the first three octets are your network ID. You have to make sure you put the correct net ID in.

do this:
iptables -t nat -A POSTROUTING -o eth0 -s 192.168.1.0/24 -j SNAT --to 192.168.1.31

thank you bentman78. but it didn't work.
I just wanted to route one particular IP 192.168.1.33.
that is why I used:
iptables -t nat -A POSTROUTING -o eth0 -s 192.168.1.33 -j SNAT --to 192.168.1.31
with what you suggested:
iptables -t nat -A POSTROUTING -o eth0 -s 192.168.1.0/24 -j SNAT --to 192.168.1.31
it is supposed to route the whole network instead of only one IP. It would be fine with me, but unfortunatelly it doesn't work neither.

Andrzej

anyone ??

why do u ask hard question?
how is your pc1 routing table?
what "route -n" shows in pc1?

bash-2.05b# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
0.0.0.0 192.168.1.1 0.0.0.0 UG 1 0 0 eth0

I'm not good at this routing thing, but I think it might help, you provide more info, like error message when pinging, ftp, web from all three machine.

i think when u try to ping it it will prefer eth0 interface to reach 192.168.1.33 .
can u ping pc2 from pc1?
try to add route:
/sbin/route add -host 192.168.1.33 dev eth1

if it still doesnt work, u must prefer bridge or routing.


by the when u change 192.168.1.33/24 to 192.168.0.33/24 routing will work fine, and 192.168.0.33/24 (pc2) can also access internet. apply SNAT rule for 192.168.0.33/24 so your gateway will see only 192.168.1.31 ip. it wont understand if ip of pc2 is 192.168.0.33/24. it just will see 192.168.1.31.
iptables -t nat -A POSTROUTING -s 192.168.0.33 -j SNAT --to 192.168.1.31