diff -up openssh-5.5p1/auth-krb5.c.kuserok openssh-5.5p1/auth-krb5.c
--- openssh-5.5p1/auth-krb5.c.kuserok	2010-06-08 11:40:10.000000000 +0200
+++ openssh-5.5p1/auth-krb5.c	2010-06-08 11:40:11.000000000 +0200
@@ -146,9 +146,11 @@ 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;
+		}
 	}
 
 	problem = ssh_krb5_cc_gen(authctxt->krb5_ctx, &authctxt->krb5_fwd_ccache);
diff -up openssh-5.5p1/servconf.c.kuserok openssh-5.5p1/servconf.c
--- openssh-5.5p1/servconf.c.kuserok	2010-06-08 11:40:10.000000000 +0200
+++ openssh-5.5p1/servconf.c	2010-06-08 11:46:20.000000000 +0200
@@ -137,6 +137,7 @@ initialize_server_options(ServerOptions 
 	options->zero_knowledge_password_authentication = -1;
 	options->revoked_keys_file = NULL;
 	options->trusted_user_ca_keys = NULL;
+	options->use_kuserok = -1;
 }
 
 void
@@ -285,6 +286,8 @@ 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 "
@@ -306,7 +309,7 @@ typedef enum {
 	sPermitRootLogin, sLogFacility, sLogLevel,
 	sRhostsRSAAuthentication, sRSAAuthentication,
 	sKerberosAuthentication, sKerberosOrLocalPasswd, sKerberosTicketCleanup,
-	sKerberosGetAFSToken,
+	sKerberosGetAFSToken, sKerberosUseKuserok,
 	sKerberosTgtPassing, sChallengeResponseAuthentication,
 	sPasswordAuthentication, sKbdInteractiveAuthentication,
 	sListenAddress, sAddressFamily,
@@ -376,11 +379,13 @@ 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 },
@@ -1335,6 +1340,10 @@ 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')
@@ -1517,6 +1526,7 @@ 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)
@@ -1734,6 +1744,7 @@ 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-5.5p1/servconf.h.kuserok openssh-5.5p1/servconf.h
--- openssh-5.5p1/servconf.h.kuserok	2010-06-08 11:40:10.000000000 +0200
+++ openssh-5.5p1/servconf.h	2010-06-08 11:40:11.000000000 +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-5.5p1/sshd_config.5.kuserok openssh-5.5p1/sshd_config.5
--- openssh-5.5p1/sshd_config.5.kuserok	2010-06-08 11:40:10.000000000 +0200
+++ openssh-5.5p1/sshd_config.5	2010-06-08 11:40:11.000000000 +0200
@@ -519,6 +519,10 @@ 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).
@@ -644,6 +648,7 @@ Available keywords are
 .Cm HostbasedAuthentication ,
 .Cm KbdInteractiveAuthentication ,
 .Cm KerberosAuthentication ,
+.Cm KerberosUseKuserok ,
 .Cm MaxAuthTries ,
 .Cm MaxSessions ,
 .Cm PasswordAuthentication ,
diff -up openssh-5.5p1/sshd_config.kuserok openssh-5.5p1/sshd_config
--- openssh-5.5p1/sshd_config.kuserok	2010-06-08 11:40:10.000000000 +0200
+++ openssh-5.5p1/sshd_config	2010-06-08 11:40:11.000000000 +0200
@@ -72,6 +72,7 @@ ChallengeResponseAuthentication no
 #KerberosOrLocalPasswd yes
 #KerberosTicketCleanup yes
 #KerberosGetAFSToken no
+#KerberosUseKuserok yes
 
 # GSSAPI options
 #GSSAPIAuthentication no