Re: Networking messed up, bad checksum, incorrect length

[Carlos Velasco <lkml@newipnet.com>]

Herbert Xu escribió:

> These packets look like normal TSO packets.  Linux will send a
> packet containing more data than fits in a packet to the NIC.  The
> NIC will then segment the packet for us.
> 
> If that is not possible, you can try disabling TSO with ethtool -K.

I see...
I have tracked the change to 2.6.18.
Using kernel 2.6.17.14 and below makes tcpdump/libpcap to display the
real packets.
Could this be a change in the tg3 driver to support TSO committed in 2.6.18?

And a question... how this TSO affects netfilter?

> In order to see what really goes out, you'll need to run a packet
> dump beyond the NIC.

They are here:

Sniffer traces taken through port mirroring in the switch
(ethereal with filter: host flash.cnio.es):
http://www.nimastelecom.com/smtptraces/smtptrace_portmirror.pcap


But still wondering how could this affect Netfilter... my real problem
is that Netfilter drops ACK packets because it doesn't see the
connection established/related.

I will try to do some more research.

Regards,
Carlos Velasco
CCNP & CCDP Cisco Certified Network Professional


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