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Re: NAT and IPTABLES problem. I SOLVED My problem, thanks for all the help provided.



Well all  I had to do, was to increase  Time to live, on PRerouting, so the firewall to be able to forward the packet.
This litttle baby did the job.
iptables -t mangle -A PREROUTING -i eth1 -j TTL --ttl-inc 1

Manny Thanks Again
Mihai

----- Original Message ----
From: chindea mihai <misubs24@yahoo.com>
To: Bonnel Christophe <mage.tophinus@free.fr>
Cc: debian-amd64@lists.debian.org
Sent: Thursday, April 3, 2008 8:24:51 AM
Subject: Re: Fw: NAT and IPTABLES problem

Hi

I usually used the host name.: ping yahoo.com.  But the translate between hostname and hostaddress seems to work fine.And yeah the DND server, for subnet is my gateway.
I did reboot my gateway a couple of times, and it didn't make any difference.
My laptop has Debian Lenny installed, and windows, but I'm usually using linux.
I don't know what this "ifconfig mtu 1450" was suppose to do but it's not working, I mean it's kinda obvious that's not working, cause I got no device with that name, and that's exactly the encountered error:

work:/#ifconfig mtu  1450
 SIOCSIFADDR: no such device
 mtu: ERROR while getting interface flags: No such device
work:/#
 
I tried those commands, and verified with cat, they seem to succeed, but unfortunately no result,same problem, ping isn't working.

Now, by mistake I tried to ping the gateway provided by my ISP, from my laptop, and it's working. I mean, I get the reply, on my laptop. I may be wrong but I guess IPtables mess up the ports, of course I couldn't figure it out why.

Mihai,

----- Original Message ----
From: Bonnel Christophe <mage.tophinus@free.fr>
To: chindea mihai <misubs24@yahoo.com>
Cc: debian-amd64@lists.debian.org
Sent: Wednesday, April 2, 2008 6:31:20 PM
Subject: Re: Fw: NAT and IPTABLES problem

What kind of ping do you use ? ping www.yahoo.com or ping 216.109.112.135 ?
If you ping www.yahoo.com, i think dns server is your gateway, isn't it ?

Ok, so your vmware is installed of your gateway. It may not use your
debian as gateway and go directly through your eth2 interface ....

It doesn't seem that the problem comes from the iptables or kernel
version...

Do you reboot your gateway at least one time since the problem starts ?


It becomes very difficult. I hope (and assume) your laptop is linux
too... Can you try this on your laptop :

ifconfig mtu 1450
echo "0" > /proc/sys/net/ipv4/tcp_window_scaling
echo "0" > /proc/sys/net/ipv4/tcp_ecn
(verify the values with "cat" and "ifconfig" commands)

And now try to ping and give us the result ? Does it works or not ?

Christophe


chindea mihai a écrit :
> Hi,
>
> After restarting iptables:
>
> /etc/network# iptables -t filter -L FORWARD -v -n
> Chain FORWARD (policy DROP 0 packets, 0 bytes)
>  pkts bytes target    prot opt in    out    source             
> destination
>    20  1032 ACCEPT    0    --  eth2  eth1    192.168.5.0/24     
> 0.0.0.0/0
>    0    0 ACCEPT    0    --  *      *      0.0.0.0/0           
> 0.0.0.0/0          state RELATED,ESTABLISHED
>    0    0 LOG        0    --  *      eth1    0.0.0.0/0           
> 192.168.5.0/24      LOG flags 0 level 4
>    0    0 DROP      0    --  *      eth1    0.0.0.0/0           
> 192.168.5.0/24
>    0    0 LOG        0    --  *      *      0.0.0.0/0           
> 0.0.0.0/0          LOG flags 0 level 4
>    0    0 DROP      0    --  *      *      0.0.0.0/0           
> 0.0.0.0/0
> /etc/network# 
>
> /etc/network# iptables -t nat -L POSTROUTING -v -n
> Chain POSTROUTING (policy ACCEPT 51 packets, 2847 bytes)
>  pkts bytes target    prot opt in    out    source             
> destination
>    16  888 MASQUERADE  0    --  *      eth1    192.168.5.0/24     
> 0.0.0.0/0
> /etc/network#
>                           
> After Adding those two rulles:
>
> General forward : IN=eth2 OUT=eth1 SRC=""
> DST=216.109.112.135 LEN=60 TOS=0x00 PREC=0x00 TTL=127 ID=234
> PROTO=ICMP TYPE=8 CODE=0 ID=1 SEQ=12
> General forward : IN=eth2 OUT=eth1 SRC=""
> DST=216.109.112.135 LEN=60 TOS=0x00 PREC=0x00 TTL=127 ID=235
> PROTO=ICMP TYPE=8 CODE=0 ID=1 SEQ=13
> General forward : IN=eth2 OUT=eth1 SRC=""
> DST=216.109.112.135 LEN=60 TOS=0x00 PREC=0x00 TTL=127 ID=236
> PROTO=ICMP TYPE=8 CODE=0 ID=1 SEQ=14
> General forward : IN=eth2 OUT=eth1 SRC=""
> DST=216.109.112.135 LEN=60 TOS=0x00 PREC=0x00 TTL=127 ID=237
> PROTO=ICMP TYPE=8 CODE=0 ID=1 SEQ=15
>    So you were right...
>
> The rest of informations:
>    /etc/network# iptables --version
>    iptables v1.3.6
>    /etc/network# uname -r
>    2.6.18-6-amd64
>
> About Vmware, I suppose your're thinking to vmware esx Server cause
> that is OS independent. I'm using vmware workstation, which is
> installed over Debian, but as Alex said, vmware has it's own network
> modules. Ping attemps from an guest OS it's working fine.
>
> Thanks,
> Mihai



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