In case when kerberos authentication is correctly configured in security realm [1] and Management CLI which runs with JDK 1.6 tries to connected then following exception is thrown:

Exception in thread "Remoting "cli-client" task-1" java.lang.SecurityException: Unable to locate a login configuration
	at com.sun.security.auth.login.ConfigFile.<init>(ConfigFile.java:93)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
	at java.lang.Class.newInstance0(Class.java:357)
	at java.lang.Class.newInstance(Class.java:310)
	at javax.security.auth.login.Configuration$3.run(Configuration.java:247)
	at java.security.AccessController.doPrivileged(Native Method)
	at javax.security.auth.login.Configuration.getConfiguration(Configuration.java:242)
	at sun.security.jgss.LoginConfigImpl$1.run(LoginConfigImpl.java:47)
	at sun.security.jgss.LoginConfigImpl$1.run(LoginConfigImpl.java:45)
	at java.security.AccessController.doPrivileged(Native Method)
	at sun.security.jgss.LoginConfigImpl.<init>(LoginConfigImpl.java:44)
	at sun.security.jgss.GSSUtil.login(GSSUtil.java:244)
	at sun.security.jgss.krb5.Krb5Util.getTicket(Krb5Util.java:136)
	at sun.security.jgss.krb5.Krb5InitCredential$1.run(Krb5InitCredential.java:328)
	at java.security.AccessController.doPrivileged(Native Method)
	at sun.security.jgss.krb5.Krb5InitCredential.getTgt(Krb5InitCredential.java:325)
	at sun.security.jgss.krb5.Krb5InitCredential.getInstance(Krb5InitCredential.java:128)
	at sun.security.jgss.krb5.Krb5MechFactory.getCredentialElement(Krb5MechFactory.java:106)
	at sun.security.jgss.krb5.Krb5MechFactory.getMechanismContext(Krb5MechFactory.java:172)
	at sun.security.jgss.GSSManagerImpl.getMechanismContext(GSSManagerImpl.java:209)
	at sun.security.jgss.GSSContextImpl.initSecContext(GSSContextImpl.java:195)
	at sun.security.jgss.GSSContextImpl.initSecContext(GSSContextImpl.java:162)
	at com.sun.security.sasl.gsskerb.GssKrb5Client.evaluateChallenge(GssKrb5Client.java:175)
	at org.jboss.remoting3.remote.ClientConnectionOpenListener$Capabilities$2$1.run(ClientConnectionOpenListener.java:463)
	at org.jboss.remoting3.remote.ClientConnectionOpenListener$Capabilities$2$1.run(ClientConnectionOpenListener.java:459)
	at java.security.AccessController.doPrivileged(Native Method)
	at org.jboss.remoting3.remote.ClientConnectionOpenListener$Capabilities$2.run(ClientConnectionOpenListener.java:459)
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
	at java.lang.Thread.run(Thread.java:662)
Caused by: java.io.IOException: Unable to locate a login configuration
	at com.sun.security.auth.login.ConfigFile.init(ConfigFile.java:250)
	at com.sun.security.auth.login.ConfigFile.<init>(ConfigFile.java:91)
	... 32 more

How to reproduce:
1) configure kerberos authentication for Management Realm with wrong configured principal
2) start Kerberos server and EAP, try to authenticate into Management CLI with JDK 1.7 - works fine
3) disconnect from Management CLI
4) try to authenticate into Management CLI with JDK 1.6 - mentioned above exception is thrown

I request blocker flag since this issue is blocking certification [1] for JDK6. 

[1] http://darranl.blogspot.cz/2014/11/wildfly-9-kerberos-authentication-with.html
[2] https://mojo.redhat.com/docs/DOC-48621