Index: share/man/man4/tcp.4
===================================================================
--- share/man/man4/tcp.4
+++ share/man/man4/tcp.4
@@ -34,7 +34,7 @@
 .\"     From: @(#)tcp.4	8.1 (Berkeley) 6/5/93
 .\" $FreeBSD$
 .\"
-.Dd March 23, 2019
+.Dd July 17, 2019
 .Dt TCP 4
 .Os
 .Sh NAME
@@ -606,6 +606,10 @@
 .It Va insecure_syn
 Use criteria defined in RFC793 instead of RFC5961 for accepting SYN segments.
 Default is false.
+.It Va ts_offset_per_conn
+When initializing the TCP timestamps, use a per connection offset instead of a
+per host pair offset.
+Default is to use per connection offsets as recommended in RFC 7323.
 .El
 .Sh ERRORS
 A socket operation may fail with one of the following errors returned:
Index: sys/netinet/tcp_subr.c
===================================================================
--- sys/netinet/tcp_subr.c
+++ sys/netinet/tcp_subr.c
@@ -195,6 +195,11 @@
     &VNET_NAME(tcp_do_rfc1323), 0,
     "Enable rfc1323 (high performance TCP) extensions");
 
+VNET_DEFINE(int, tcp_ts_offset_per_conn) = 1;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, ts_offset_per_conn, CTLFLAG_VNET | CTLFLAG_RW,
+    &VNET_NAME(tcp_ts_offset_per_conn), 0,
+    "Initialize TCP timestamps per connection instead of per host pair");
+
 static int	tcp_log_debug = 0;
 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_debug, CTLFLAG_RW,
     &tcp_log_debug, 0, "Log errors caused by incoming TCP segments");
@@ -2634,7 +2639,17 @@
 uint32_t
 tcp_new_ts_offset(struct in_conninfo *inc)
 {
-	return (tcp_keyed_hash(inc, V_ts_offset_secret,
+	struct in_conninfo inc_store, *local_inc;
+
+	if (!V_tcp_ts_offset_per_conn) {
+		memcpy(&inc_store, inc, sizeof(struct in_conninfo));
+		inc_store.inc_lport = 0;
+		inc_store.inc_fport = 0;
+		local_inc = &inc_store;
+	} else {
+		local_inc = inc;
+	}
+	return (tcp_keyed_hash(local_inc, V_ts_offset_secret,
 	    sizeof(V_ts_offset_secret)));
 }
 
Index: sys/netinet/tcp_var.h
===================================================================
--- sys/netinet/tcp_var.h
+++ sys/netinet/tcp_var.h
@@ -802,6 +802,7 @@
 #define	V_tcp_do_autosndbuf		VNET(tcp_do_autosndbuf)
 #define	V_tcp_do_ecn			VNET(tcp_do_ecn)
 #define	V_tcp_do_rfc1323		VNET(tcp_do_rfc1323)
+#define V_tcp_ts_offset_per_conn	VNET(tcp_ts_offset_per_conn)
 #define	V_tcp_do_rfc3042		VNET(tcp_do_rfc3042)
 #define	V_tcp_do_rfc3390		VNET(tcp_do_rfc3390)
 #define	V_tcp_do_rfc3465		VNET(tcp_do_rfc3465)