data nodes can't reach name node

[#1]

My data nodes in my new cloudera live cluster seem unable to reach the master node. I've tried restarting HDFS several times from Cloudera Manager and I get the following error message:

"Command aborted because of exception: Command timed-out after 150 seconds"

I can login to each machine using root and the passwords provided on the gogrid page. Should ssh be set up between these machines to not require entering a password? I'm not sure if I missed a step in the configuration or if it should be done automatically when the cluster is first deployed; of course it could be some other connectivity problem.

I think the following is a symptom of the same connectivity problem. If I ssh to one of the data nodes (I anonymized part of the hostname) and try to run this command, I get this error:

[root@XXXXX-cldraagent-01 ~]# hadoop fs -ls /user/hue
ls: No Route to Host from XXXXX-cldraagent-01/10.NNN.NNN.3 to XXXXX-cldramaster-01:8020 failed on socket timeout exception: java.net.NoRouteToHostException: No route to host; For more details see: http://wiki.apache.org/hadoop/NoRouteToHost

I can ping the master from the agent (again anonymizing):

ping XXXXX-cldramaster-01
PING XXXXX-cldramaster-01 (10.NNN.NNN.2) 56(84) bytes of data.
64 bytes from XXXXX-cldramaster-01 (10.NNN.NNN.2): icmp_seq=1 ttl=64 time=0.276 ms
64 bytes from XXXXX-cldramaster-01 (10.NNN.NNN.2): icmp_seq=2 ttl=64 time=0.358 ms

Appreciate any pointers, and apologies if this is a stupid question

[#2 · Accepted solution]

For what it's worth in case somebody else encounters a similar problem, after adding ssh keys I had the same problem but I found the following instructions:

http://www.cyberciti.biz/tips/no-route-to-host-error-and-solution.html

I ran these commands on the master (name node), and now hdfs is working properly on all 4 nodes

/sbin/iptables -L -n

/etc/init.d/iptables save

/etc/init.d/iptables stop

/sbin/iptables -L -n

[#3]

for my case I was just working on cloudera VM , I had to configure the node ip ,
=> ifconfig LOCAL_NODE_IP eth1:2 netmask XXXX
after that pinging to that ip is going well
thanks a lot

[#4]

thanks