diff -up openssh-7.1p1/ssh_config.5.gss-docs openssh-7.1p1/ssh_config.5
--- openssh-7.1p1/ssh_config.5.gss-docs	2015-12-10 15:28:47.451966457 +0100
+++ openssh-7.1p1/ssh_config.5	2015-12-10 15:30:28.070738047 +0100
@@ -773,15 +773,26 @@ Note that this option applies to protoco
 If set to 
 .Dq yes
 then renewal of the client's GSSAPI credentials will force the rekeying of the
-ssh connection. With a compatible server, this can delegate the renewed 
+ssh connection. With a compatible server, this will delegate the renewed 
 credentials to a session on the server.
+.Pp
+Checks are made to ensure that credentials are only propagated when the new
+credentials match the old ones on the originating client and where the
+receiving server still has the old set in its cache.
+.Pp
 The default is
 .Dq no .
+.Pp
+For this to work
+.Cm GSSAPIKeyExchange
+needs to be enabled in the server and also used by the client.
 .It Cm GSSAPITrustDns
 Set to 
-.Dq yes to indicate that the DNS is trusted to securely canonicalize
+.Dq yes
+to indicate that the DNS is trusted to securely canonicalize
 the name of the host being connected to. If 
-.Dq no, the hostname entered on the
+.Dq no ,
+the hostname entered on the
 command line will be passed untouched to the GSSAPI library.
 The default is
 .Dq no .
diff -up openssh-7.1p1/sshd_config.5.gss-docs openssh-7.1p1/sshd_config.5
--- openssh-7.1p1/sshd_config.5.gss-docs	2015-12-10 15:28:47.453966452 +0100
+++ openssh-7.1p1/sshd_config.5	2015-12-10 15:28:47.461966434 +0100
@@ -653,6 +653,10 @@ Controls whether the user's GSSAPI crede
 successful connection rekeying. This option can be used to accepted renewed 
 or updated credentials from a compatible client. The default is
 .Dq no .
+.Pp
+For this to work
+.Cm GSSAPIKeyExchange
+needs to be enabled in the server and also used by the client.
 .It Cm HostbasedAcceptedKeyTypes
 Specifies the key types that will be accepted for hostbased authentication
 as a comma-separated pattern list.