Connection tracking looses packets?

[Mike Polek <mike@pictage.com>]

Hi,

For anyone interested, I was attempting to set up a load balancing
FTP server, which I've done before. I had a brand new kernel,
installed the nfct patches, etc. Not knowing that there had
been a tcp-window-tracking patch to the kernel, I couldn't figure
out why the first passive connection would always work, but
later passive connections would fail. After poking around, I could
see the (*pskb)->nfct pointer was NULL, and I was completely
stumped.

Thanks to Pascal Hambourg's post, I tried

echo 1 > /proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_be_liberal

and magically, everything works perfectly, just like the old server.

I hope this helps others who are load balancing ftp servers.

Thanks to everyone who contributes to Open Source and these
mailing lists!!!

Mike Polek
Pictage, Inc.