No route to host

[Damian Keska]

Hello,

I tried to connect to a host in another cloud, but traceroute shows just "* * *".
It worked, then stopped unexpectedly without a known reason.

1) From the second cloud the traceroute looks ok, there are packets sent to Google Cloud Compute Instance, but it does not respond.

2) From inside Google Cloud Compute Instance the traceroute shows just "* * *" to that host in second cloud. 

3) From inside Google Cloud I can access the third cloud, any almost any host without any issue

4) Created a new project in Google Cloud, added a new virtual machine, tried curl - the same thing

Any hints?

Thanks.

[pralove]

A hop that outputs * * * means that the router at that hop doesn't respond to the type of packet you were using for the traceroute (by default it's UDP on Unix-like and ICMP on Windows)[1].

Three probes (change with -q flag) are sent at each ttl setting and a line is printed showing the ttl, address of the gateway and round trip time of each probe( so three * ). If there is no response within a 5 sec. timeout interval (changed with the -w flag), a "*" is printed for that probe[2].

This[3] is the other link explains about why "* * *" may occur.

I hope this helps. 

[1] https://serverfault.com/a/334034/545803

[2] https://serverfault.com/a/334039/545803

[3] https://www.redhat.com/sysadmin/traceroute-finding-meaning