Index: usr.bin/sockstat/sockstat.1
===================================================================
--- usr.bin/sockstat/sockstat.1
+++ usr.bin/sockstat/sockstat.1
@@ -27,7 +27,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd July 3, 2018
+.Dd April 14, 2020
 .Dt SOCKSTAT 1
 .Os
 .Sh NAME
@@ -36,6 +36,7 @@
 .Sh SYNOPSIS
 .Nm
 .Op Fl 46cLlSsUuvw
+.Op Fl J Ar jid
 .Op Fl j Ar jid
 .Op Fl p Ar ports
 .Op Fl P Ar protocols
@@ -58,6 +59,9 @@
 (IPv6) sockets.
 .It Fl c
 Show connected sockets.
+.It Fl J Ar jail
+Attach to the specified jail ID or name.
+This is useful for inspecting VNET jails, which have their own network stack.
 .It Fl j Ar jail
 Show only sockets belonging to the specified jail ID or name.
 .It Fl L
Index: usr.bin/sockstat/sockstat.c
===================================================================
--- usr.bin/sockstat/sockstat.c
+++ usr.bin/sockstat/sockstat.c
@@ -37,6 +37,7 @@
 #include <sys/sysctl.h>
 #include <sys/file.h>
 #include <sys/user.h>
+#include <sys/jail.h>
 
 #include <sys/un.h>
 #define	_WANT_UNPCB
@@ -74,6 +75,7 @@
 static int	 opt_4;		/* Show IPv4 sockets */
 static int	 opt_6;		/* Show IPv6 sockets */
 static int	 opt_c;		/* Show connected sockets */
+static int	 opt_J;		/* Attach to specified jail */
 static int	 opt_j;		/* Show specified jail */
 static int	 opt_L;		/* Don't show IPv4 or IPv6 loopback sockets */
 static int	 opt_l;		/* Show listening sockets */
@@ -1251,8 +1253,8 @@
 	int protos_defined = -1;
 	int o, i;
 
-	opt_j = -1;
-	while ((o = getopt(argc, argv, "46cj:Llp:P:qSsUuvw")) != -1)
+	opt_J = opt_j = -1;
+	while ((o = getopt(argc, argv, "46cJ:j:Llp:P:qSsUuvw")) != -1)
 		switch (o) {
 		case '4':
 			opt_4 = 1;
@@ -1263,6 +1265,11 @@
 		case 'c':
 			opt_c = 1;
 			break;
+		case 'J':
+			opt_J = jail_getid(optarg);
+			if (opt_J < 0)
+				errx(1, "%s", jail_errmsg);
+			break;
 		case 'j':
 			opt_j = jail_getid(optarg);
 			if (opt_j < 0)
@@ -1310,6 +1317,9 @@
 
 	if (argc > 0)
 		usage();
+
+	if (opt_J >= 0 && jail_attach(opt_J) != 0)
+		errx(1, "%s", jail_errmsg);
 
 	if ((!opt_4 && !opt_6) && protos_defined != -1)
 		opt_4 = opt_6 = 1;