Saturday, April 27, 2019

Error: No route to host while ICMP is working


   We try to access a port 1521 service in a VM which has Oracle Linux 7.6 . Ping (ICMP) is working fine. But we get error when we test port via nc or telnet
Ncat: No route to host.


  There are quite a few reasons for that.

  • check your subnet security list, make sure ports are open
  • use traceroute and dig to check route table is working as expected
  • check target VM linux firewalld is up 
In our case, firewalld is up by default, it blocks traffic of  1521. The error message is confusing people "Ncat: No route to host." . It is not about route. It is due to traffic blocked by target host Linux
Fix it via systemctl stop firewalld ;systemctl disable firewalld

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