From: Florian Westphal <[email protected]> When zero window is announced we can get into a situation where connection stays around forever:
1. One side announces zero window. 2. Other side closes. In this case, no FIN is sent (stuck in send queue). Unless other side opens the window up again conntrack stays in ESTABLISHED state for a very long time. Lets alleviate this by lowering the timeout to RETRANS (5 minutes), the other end should be sending zero window probes to keep the connection established as long as a socket still exists. Cc: Jozsef Kadlecsik <[email protected]> Signed-off-by: Florian Westphal <[email protected]> Acked-by: Jozsef Kadlecsik <[email protected]> Signed-off-by: Pablo Neira Ayuso <[email protected]> --- net/netfilter/nf_conntrack_proto_tcp.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c index b12fc07111d0..37ef35b861f2 100644 --- a/net/netfilter/nf_conntrack_proto_tcp.c +++ b/net/netfilter/nf_conntrack_proto_tcp.c @@ -1039,6 +1039,9 @@ static int tcp_packet(struct nf_conn *ct, IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED && timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK]) timeout = timeouts[TCP_CONNTRACK_UNACK]; + else if (ct->proto.tcp.last_win == 0 && + timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS]) + timeout = timeouts[TCP_CONNTRACK_RETRANS]; else timeout = timeouts[new_state]; spin_unlock_bh(&ct->lock); -- 2.11.0
