The packet is not flagged as invalid: conntrack will accept it and its associated with the conntrack entry. This happens e.g. when receiving a retransmitted SYN in SYN_RECV state. Signed-off-by: Florian Westphal <fw@xxxxxxxxx> --- net/netfilter/nf_conntrack_proto_tcp.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c index 1d7e1c595546..ec23330687a5 100644 --- a/net/netfilter/nf_conntrack_proto_tcp.c +++ b/net/netfilter/nf_conntrack_proto_tcp.c @@ -982,8 +982,10 @@ int nf_conntrack_tcp_packet(struct nf_conn *ct, IP_CT_EXP_CHALLENGE_ACK; } spin_unlock_bh(&ct->lock); - nf_ct_l4proto_log_invalid(skb, ct, "invalid packet ignored in " - "state %s ", tcp_conntrack_names[old_state]); + nf_ct_l4proto_log_invalid(skb, ct, + "packet (index %d) in dir %d ignored, state %s", + index, dir, + tcp_conntrack_names[old_state]); return NF_ACCEPT; case TCP_CONNTRACK_MAX: /* Special case for SYN proxy: when the SYN to the server or -- 2.26.2
