Messages in this thread | | | From | "Josan Kadett" <> | Subject | RE: Entirely ignoring TCP and UDP checksum in kernel level | Date | Sun, 22 Aug 2004 21:27:25 +0200 |
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Very well I am trying to ping this device from a host connected to our linux box whose source IP is translated. I changed the IP numbers a bit so they won't interfere with each ether in any way (absolutely different subnets)
Eth0 is connected the path where the problematic 192.168.77.1 is reached. The IP number of assigned to eth1 interface is 192.168.1.5. Now with the patch applied, any request to 192.167.77.1 seems to return from 192.168.77.1
Eth1 is connected to a private network with the IP address of 1.1.1.1, and the IP address of the host whose connection will be SNATted is 1.1.1.30.
When I ping 192.168.77.1, everything seems correct now, but when I ping that IP 1.1.1.30, indeed the transaction is made, but the linux box is somehow "reluctant" to send te response back.
Iptables -L -n -t nat: Chain POSTROUTING (policy ACCEPT) Target prot opt source destination SNAT all -- 0.0.0.0/0 0.0.0.0/0 to:192.168.1.2
0.0.0.0 means anywhere I presume...
Ifconfig of the patched box Eth0: inet address 192.168.1.5, netmask 255.255.0.0 (external if) Eth1: inet address 1.1.1.1, netmak 255.255.255.0 (internal if)
Routing tables: Destination Gateway Genmaks Flags Metric Ref Use Iface 192.168.77.1 192.168.1.2 255.255.255.0 UGH 0 0 0 eth0 1.1.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1 192.168.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
NAT client uses IP address 1.1.1.30, with netmask of 255.255.255.0 with the default gateway 1.1.1.1 (linux box).
Tcpdump[ eth0 / the address translation occurs correctly] Ping request - 192.168.1.5 to 192.168.77.1 Ping reply - From 192.168.77.1 to 192.168.1.5 Ping request - 192.168.1.5 to 192.168.77.1 Ping reply - From 192.168.77.1 to 192.168.1.5 Ping request - 192.168.1.5 to 192.168.77.1 Ping reply - From 192.168.77.1 to 192.168.1.5
Tcpdump[ eth1 / no reply is sent by our linux system] Ping request - 1.1.1.30 to 192.168.77.1 Ping request - 1.1.1.30 to 192.168.77.1 Ping request - 1.1.1.30 to 192.168.77.1
Both dumps are taken at the same time, I ensure that the linux box just does not redirect the ping reply to the client 1.1.1.30 that requested it.
What can this be now? NAT still does not work in a way - or is there something missing ?
-----Original Message----- From: Brad Campbell [mailto:brad@wasp.net.au] Sent: Sunday, August 22, 2004 3:14 PM To: Josan Kadett Cc: linux-kernel@vger.kernel.org Subject: Re: Entirely ignoring TCP and UDP checksum in kernel level
Are you trying to ping 192.168.77.1 from 192.168.0.30?
Can you give me an iptables -L -n -t nat, ifconfig and route -n from the patched box and also route -n and ifconfig from the dummy client at 192.168.0.30 so I can try and get a handle on what you are doing and how it all is supposed to work?
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