// SPDX-License-Identifier: GPL-2.0-only
/* (C) 1999-2001 Paul `Rusty' Russell
* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
* (C) 2002-2013 Jozsef Kadlecsik <kadlec@netfilter.org>
* (C) 2006-2012 Patrick McHardy <kaber@trash.net>
*/
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/module.h>
#include <linux/in.h>
#include <linux/tcp.h>
#include <linux/spinlock.h>
#include <linux/skbuff.h>
#include <linux/ipv6.h>
#include <net/ip6_checksum.h>
#include <asm/unaligned.h>
#include <net/tcp.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_ipv6.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_l4proto.h>
#include <net/netfilter/nf_conntrack_ecache.h>
#include <net/netfilter/nf_conntrack_seqadj.h>
#include <net/netfilter/nf_conntrack_synproxy.h>
#include <net/netfilter/nf_conntrack_timeout.h>
#include <net/netfilter/nf_log.h>
#include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
#include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
/* "Be conservative in what you do,
be liberal in what you accept from others."
If it's non-zero, we mark only out of window RST segments as INVALID. */
static int nf_ct_tcp_be_liberal __read_mostly = 0;
/* If it is set to zero, we disable picking up already established
connections. */
static int nf_ct_tcp_loose __read_mostly = 1;
/* Max number of the retransmitted packets without receiving an (acceptable)
ACK from the destination. If this number is reached, a shorter timer
will be started. */
static int nf_ct_tcp_max_retrans __read_mostly = 3;
/* FIXME: Examine ipfilter's timeouts and conntrack transitions more
closely. They're more complex. --RR */
static const char *const tcp_conntrack_names[] = {
"NONE",
"SYN_SENT",
"SYN_RECV",
"ESTABLISHED",
"FIN_WAIT",
"CLOSE_WAIT",