upstream commit

mention that the default of UseDNS=no implies that
 hostnames cannot be used for host matching in sshd_config and
 authorized_keys; bz#2045, ok dtucker@

Upstream-ID: 0812705d5f2dfa59aab01f2764ee800b1741c4e1

sshd_config.5

@@ -33,8 +33,8 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: sshd_config.5,v 1.206 2015/07/10 06:21:53 markus Exp $
-.Dd $Mdocdate: July 10 2015 $
+.\" $OpenBSD: sshd_config.5,v 1.207 2015/07/20 00:30:01 djm Exp $
+.Dd $Mdocdate: July 20 2015 $
 .Dt SSHD_CONFIG 5
 .Os
 .Sh NAME
@@ -1493,11 +1493,20 @@ For more details on certificates, see the CERTIFICATES section in
 .It Cm UseDNS
 Specifies whether
 .Xr sshd 8
-should look up the remote host name and check that
+should look up the remote host name, and to check that
 the resolved host name for the remote IP address maps back to the
 very same IP address.
-The default is
-.Dq no .
+.Pp
+If this option is set to
+.Dq no
+(the default) then only addresses and not host names may be used in
+.Pa ~/.ssh/known_hosts
+.Cm from
+and
+.Xr sshd_config 5
+.Cm Match
+.Cm Host
+directives.
 .It Cm UseLogin
 Specifies whether
 .Xr login 1