You can find many details in the JBoss Fuse documentation (eg successor to Fuse ESB) at
And there is a chapter on remote connecting to containers here
You need to pass in credentials for a user on the container that is valid and is in the admin role.
The karaf shell also has a jaas command, which allows you to list the users and their roles etc. And as well add new users, etc. You can also do some user management form the FMC web console that is part of Fuse ESB.