[CentOS] elasticsearch connection refused

Hallo,
is anyone here using elasticsearch on centos?
I tried several configs to configure external access but nothing is working.
My tests:
telnet localhost or 127.0.0.1 9200 works local on the machine
telnet 192.168.242.4 9200 connection refused local on the machine. So  
it is clear that access from other systems can not work.
Is there perhaps something special to consider when using centos 7?

Thanks for hints.

Ralf