diff -up openssh-5.6p1/auth-krb5.c.kuserok openssh-5.6p1/auth-krb5.c

--- openssh-5.6p1/auth-krb5.c.kuserok	2010-09-15 15:39:48.000000000 +0200

+++ openssh-5.6p1/auth-krb5.c	2010-09-15 15:39:48.000000000 +0200

@@ -146,9 +146,21 @@ auth_krb5_password(Authctxt *authctxt, c

 	if (problem)

 		goto out;

-	if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user, client)) {

-		problem = -1;

-		goto out;

+	if (options.use_kuserok) {

+		if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user, client)) {

+			problem = -1;

+			goto out;

+		}

+	} else {

+		char kuser[65];

+		if (krb5_aname_to_localname(authctxt->krb5_ctx, authctxt->krb5_user, sizeof(kuser), kuser)) {

+			problem = -1;

+			goto out;

+		}

+		if (strcmp(kuser, client)) {

+			problem = -1;

+			goto out;

+		}

 	}

 	problem = ssh_krb5_cc_gen(authctxt->krb5_ctx, &authctxt->krb5_fwd_ccache);

diff -up openssh-5.6p1/gss-serv-krb5.c.kuserok openssh-5.6p1/gss-serv-krb5.c

--- openssh-5.6p1/gss-serv-krb5.c.kuserok	2010-09-15 15:39:48.000000000 +0200

+++ openssh-5.6p1/gss-serv-krb5.c	2010-09-15 15:49:43.000000000 +0200

@@ -97,13 +97,25 @@ ssh_gssapi_krb5_userok(ssh_gssapi_client

 		    krb5_get_err_text(krb_context, retval));

 		return 0;

 	}

-	if (krb5_kuserok(krb_context, princ, name)) {

-		retval = 1;

-		logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",

-		    name, (char *)client->displayname.value);

-	} else

-		retval = 0;

-

+	if (options.use_kuserok) {

+		if (krb5_kuserok(krb_context, princ, name)) {

+			retval = 1;

+			logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",

+			    name, (char *)client->displayname.value);

+		} else

+			retval = 0;

+	} else {

+		char kuser[65];

+		if (krb5_aname_to_localname(krb_context, princ, sizeof(kuser), kuser))

+			retval = 0;

+		else if (strcmp(kuser, client))

+			retval = 0;

+		else {

+			retval = 1;

+			logit("Authorized to %s, krb5 principal %s (krb5)",

+			    name, (char *)client->displayname.value);

+		}

+	}

 	krb5_free_principal(krb_context, princ);

 	return retval;

 }

diff -up openssh-5.6p1/servconf.c.kuserok openssh-5.6p1/servconf.c

--- openssh-5.6p1/servconf.c.kuserok	2010-09-15 15:39:48.000000000 +0200

+++ openssh-5.6p1/servconf.c	2010-09-15 15:39:48.000000000 +0200

@@ -138,6 +138,7 @@ initialize_server_options(ServerOptions 

 	options->revoked_keys_file = NULL;

 	options->trusted_user_ca_keys = NULL;

 	options->authorized_principals_file = NULL;

+	options->use_kuserok = -1;

 }

 void

@@ -286,6 +287,8 @@ fill_default_server_options(ServerOption

 	if (use_privsep == -1)

 		use_privsep = 1;

+	if (options->use_kuserok == -1)

+		options->use_kuserok = 1;

 #ifndef HAVE_MMAP

 	if (use_privsep && options->compression == 1) {

 		error("This platform does not support both privilege "

@@ -307,7 +310,7 @@ typedef enum {

 	sPermitRootLogin, sLogFacility, sLogLevel,

 	sRhostsRSAAuthentication, sRSAAuthentication,

 	sKerberosAuthentication, sKerberosOrLocalPasswd, sKerberosTicketCleanup,

-	sKerberosGetAFSToken,

+	sKerberosGetAFSToken, sKerberosUseKuserok,

 	sKerberosTgtPassing, sChallengeResponseAuthentication,

 	sPasswordAuthentication, sKbdInteractiveAuthentication,

 	sListenAddress, sAddressFamily,

@@ -377,11 +380,13 @@ static struct {

 #else

 	{ "kerberosgetafstoken", sUnsupported, SSHCFG_GLOBAL },

 #endif

+	{ "kerberosusekuserok", sKerberosUseKuserok, SSHCFG_ALL },

 #else

 	{ "kerberosauthentication", sUnsupported, SSHCFG_ALL },

 	{ "kerberosorlocalpasswd", sUnsupported, SSHCFG_GLOBAL },

 	{ "kerberosticketcleanup", sUnsupported, SSHCFG_GLOBAL },

 	{ "kerberosgetafstoken", sUnsupported, SSHCFG_GLOBAL },

+	{ "kerberosusekuserok", sUnsupported, SSHCFG_ALL },

 #endif

 	{ "kerberostgtpassing", sUnsupported, SSHCFG_GLOBAL },

 	{ "afstokenpassing", sUnsupported, SSHCFG_GLOBAL },

@@ -1341,6 +1346,10 @@ process_server_config_line(ServerOptions

 		*activep = value;

 		break;

+	case sKerberosUseKuserok:

+		intptr = &options->use_kuserok;

+		goto parse_flag;

+

 	case sPermitOpen:

 		arg = strdelim(&cp;;

 		if (!arg || *arg == '\0')

@@ -1525,6 +1534,7 @@ copy_set_server_options(ServerOptions *d

 	M_CP_INTOPT(x11_use_localhost);

 	M_CP_INTOPT(max_sessions);

 	M_CP_INTOPT(max_authtries);

+	M_CP_INTOPT(use_kuserok);

 	M_CP_STROPT(banner);

 	if (preauth)

@@ -1745,6 +1755,7 @@ dump_config(ServerOptions *o)

 	dump_cfg_fmtint(sUseDNS, o->use_dns);

 	dump_cfg_fmtint(sAllowTcpForwarding, o->allow_tcp_forwarding);

 	dump_cfg_fmtint(sUsePrivilegeSeparation, use_privsep);

+	dump_cfg_fmtint(sKerberosUseKuserok, o->use_kuserok);

 	/* string arguments */

 	dump_cfg_string(sPidFile, o->pid_file);

diff -up openssh-5.6p1/servconf.h.kuserok openssh-5.6p1/servconf.h

--- openssh-5.6p1/servconf.h.kuserok	2010-09-15 15:39:48.000000000 +0200

+++ openssh-5.6p1/servconf.h	2010-09-15 15:39:48.000000000 +0200

@@ -157,6 +157,7 @@ typedef struct {

 	int	num_permitted_opens;

+	int	use_kuserok;

 	char   *chroot_directory;

 	char   *revoked_keys_file;

 	char   *trusted_user_ca_keys;

diff -up openssh-5.6p1/sshd_config.5.kuserok openssh-5.6p1/sshd_config.5

--- openssh-5.6p1/sshd_config.5.kuserok	2010-09-15 15:39:48.000000000 +0200

+++ openssh-5.6p1/sshd_config.5	2010-09-15 15:39:48.000000000 +0200

@@ -564,6 +564,10 @@ Specifies whether to automatically destr

 file on logout.

 The default is

 .Dq yes .

+.It Cm KerberosUseKuserok

+Specifies whether to look at .k5login file for user's aliases.

+The default is

+.Dq yes .

 .It Cm KeyRegenerationInterval

 In protocol version 1, the ephemeral server key is automatically regenerated

 after this many seconds (if it has been used).

@@ -694,6 +698,7 @@ Available keywords are

 .Cm HostbasedUsesNameFromPacketOnly ,

 .Cm KbdInteractiveAuthentication ,

 .Cm KerberosAuthentication ,

+.Cm KerberosUseKuserok ,

 .Cm MaxAuthTries ,

 .Cm MaxSessions ,

 .Cm PubkeyAuthentication ,

diff -up openssh-5.6p1/sshd_config.kuserok openssh-5.6p1/sshd_config

--- openssh-5.6p1/sshd_config.kuserok	2010-09-15 15:39:48.000000000 +0200

+++ openssh-5.6p1/sshd_config	2010-09-15 15:39:48.000000000 +0200

@@ -72,6 +72,7 @@ ChallengeResponseAuthentication no

 #KerberosOrLocalPasswd yes

 #KerberosTicketCleanup yes

 #KerberosGetAFSToken no

+#KerberosUseKuserok yes

 # GSSAPI options

 #GSSAPIAuthentication no