iptables nat issue

[Marco Catunda]

On Fri, May 23, 2008 at 9:29 PM, Mike Bird <mgb-ubuntu at yosemite.net> wrote:
> What is the source IP before the SNAT is applied?

192.168.90.1

>
> Also please show us the output of:
>
>  sudo grep . /proc/sys/net/ipv4/conf/*/forwarding

root at supgr05:~# sudo grep . /proc/sys/net/ipv4/conf/*/forwarding
/proc/sys/net/ipv4/conf/all/forwarding:0
/proc/sys/net/ipv4/conf/default/forwarding:1
/proc/sys/net/ipv4/conf/eth0/forwarding:0
/proc/sys/net/ipv4/conf/lo/forwarding:0
/proc/sys/net/ipv4/conf/tun0/forwarding:1
/proc/sys/net/ipv4/conf/vmnet1/forwarding:1
/proc/sys/net/ipv4/conf/vmnet8/forwarding:1

Great!! This is the problem. Thanks a lot. Not all interfaces was
ip_forward set to true.

I'd used the following syntax to set up ip forward:
  sysctl -w net.ipv4.conf.default.forwarding=1

But not set it up all interfaces :(

I've tweaked it using
  echo 1 > /proc/sys/net/ipv4/conf/all/forwarding
  ....
Older fashion :)

root at supgr05:~# sudo grep . /proc/sys/net/ipv4/conf/*/forwarding
/proc/sys/net/ipv4/conf/all/forwarding:1
/proc/sys/net/ipv4/conf/default/forwarding:1
/proc/sys/net/ipv4/conf/eth0/forwarding:1
/proc/sys/net/ipv4/conf/lo/forwarding:1
/proc/sys/net/ipv4/conf/tun0/forwarding:1
/proc/sys/net/ipv4/conf/vmnet1/forwarding:1
/proc/sys/net/ipv4/conf/vmnet8/forwarding:1


Everything works well.

Thanks!

>
>> I can't figure out why this is not work. The packets arrived at SERVER
>> MACHINE (I could see it
>> using tcpdump), the SERVER MACHINE reply. The reply packet arrives at
>> OFFICE MACHINE,
>> but It don't foward to tun0 device, therefore, the HOME MACHINE
>> doesn't receive reply packet.
>
> tcpdump?  Most people switched to wireshark a long time ago.  ;-)

The SERVER MACHINE is very old RedHat 3... We have to take care
some Jurassic stuffs here. :(

>
> --Mike Bird

-- 
Marco Catunda