linux - TCP connect error during parallel execution

Question

Parallel execution of a program gives me error.

 TCP connect error: ECONNREFUSED.
 DDI Process 41: error code 911
 TCP: Connect failed. node2 -> master:36883.
 TCP connect error: ECONNREFUSED.
 TCP connect error: ECONNREFUSED.
 TCP connect error: ECONNREFUSED.
 TCP connect error: ECONNREFUSED.
 TCP connect error: ECONNREFUSED.

I guess that this is due to some internal firewall of ubuntu because I am using a separate switch with no Internet connection.

I have used different information to open the port and allow ssh via ufw, but still I am getting the same error.

Could you please let me know how to overcome this problem?

Which command about iptables should I run on master and other nodes?

标签： linuxcluster-computing