Ошибка при создании учетной записи администратора

Your problem:

$ ejabberdctl register user1 1.2.3.4 pass
Can't register user user1@1.2.3.4 at node ejabberd@localhost: not_allowed

$ ejabberdctl register user1 127.0.0.1 pass
Can't register user user1@127.0.0.1 at node ejabberd@localhost: not_allowed

$ grep "^{hosts, " /etc/ejabberd/ejabberd.cfg
{hosts, ["localhost"]}.

$ ejabberdctl register user1 localhost pass
User user1@localhost successfully registered

$ ejabberdctl register user1 localhost pass
User user1@localhost already registered at node ejabberd@localhost

Solution:

$ sudo vim /etc/ejabberd/ejabberd.cfg
...

$ grep "^{hosts, " /etc/ejabberd/ejabberd.cfg
{hosts, ["localhost", "1.2.3.4"]}.

$ ejabberdctl register user7 1.2.3.4 pass                                                         
User user7@1.2.3.4 successfully registered