Re: [PATCH nf v2] netfilter: conntrack: connection timeout after re-register

Pablo Neira Ayuso
2020-10-20T15:21:44Z

On Wed, Oct 07, 2020 at 12:32:52PM -0700, Francesco Ruggeri wrote:
> If the first packet conntrack sees after a re-register is an outgoing
> keepalive packet with no data (SEG.SEQ = SND.NXT-1), td_end is set to
> SND.NXT-1.
> When the peer correctly acknowledges SND.NXT, tcp_in_window fails
> check III (Upper bound for valid (s)ack: sack <= receiver.td_end) and
> returns false, which cascades into nf_conntrack_in setting
> skb->_nfct = 0 and in later conntrack iptables rules not matching.
> In cases where iptables are dropping packets that do not match
> conntrack rules this can result in idle tcp connections to time out.

Applied, thanks.