On 04.06.2011 16:02, Julian Anastasov wrote: > > Avoid double NAT and seq adjustment for loopback > traffic because it causes silent repetition of TCP data. One > example is passive FTP with DNAT rule and difference in the > length of IP addresses. > > This patch adds checks if packet is sent and > received via loopback device. As the same conntrack is used > both for outgoing and incoming direction, we restrict NAT, > seq adjustment and confirmation to happen only in > outgoing direction (OUTPUT and POSTROUTING). > > Signed-off-by: Julian Anastasov <ja@xxxxxx> > --- > > As the check is not so cheap, another alternative > is to add new skb flag, eg. "loopback", that can be set in > drivers/net/loopback.c, loopback_xmit(). May be there is space > for it in flags2? I don't think we should be adding code specifically needed for netfilter to the loopback driver if we can avoid it. I don't think we need to actually avoid calling nf_nat_packet twice, that shouldn't do any harm, just the sequence number adjustment. So we could add the loopback check to the IPS_SEQ_ADJUST_BIT case to at least avoid it in some cases. Would that work or am I missing something? -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
