Implement IPV6_MINHOPCOUNT support.

Useful to implement GTSM support in daemons such as bgpd(8). Diff from
2013 revived by renato@.  Input from bluhm@, ok bluhm@ deraadt@

1 files changed, 10 insertions, 2 deletions

diff --git a/share/man/man4/ip6.4 b/share/man/man4/ip6.4
index f378d8d7c03..da89a961f31 100644
--- a/share/man/man4/ip6.4
+++ b/share/man/man4/ip6.4
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: ip6.4,v 1.37 2016/05/19 21:02:21 jmc Exp $
+.\"	$OpenBSD: ip6.4,v 1.38 2016/06/27 16:33:48 jca Exp $
 .\"
 .\" Copyright (c) 1983, 1991, 1993
 .\"	The Regents of the University of California.  All rights reserved.
@@ -26,7 +26,7 @@
 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
-.Dd $Mdocdate: May 19 2016 $
+.Dd $Mdocdate: June 27 2016 $
 .Dt IP6 4
 .Os
 .Sh NAME
@@ -144,6 +144,14 @@ The following socket options are supported:
 Get or set the default hop limit header field for outgoing unicast
 datagrams sent on this socket.
 A value of \-1 resets to the default value.
+.It Dv IPV6_MINHOPCOUNT Fa "int *"
+Get or set the minimum hop limit header field for incoming unicast
+datagrams received on this
+.Dv SOCK_STREAM
+socket.
+This can be used to implement the
+.Em Generalized TTL Security Mechanism (GTSM)
+according to RFC 5082.
 .It Dv IPV6_MULTICAST_IF Fa "u_int *"
 Get or set the interface from which multicast packets will be sent.
 For hosts with multiple interfaces, each multicast transmission is sent