.\" (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
.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