I was trying to get Hadoop working in standalone mode on my MBP (OS 10.9.5), but I kept getting "connection refused" errors. I found that
telnet localhost 9000 gives the same error, which is what I was told to try as a diagnostic. The same thing happens if I try
127.0.0.1 instead of
localhost, or if I try
ftp instead of
ping localhost and
ssh localhost work fine.
I had messed around a while ago with setting up an Apache server, and I'm concerned I might have broken something. At some point, I had apparently added the line:
/etc/hosts. I also had modified
httpd.conf to use the folder
~/test as my
DocumentRoot, and had changed to
extra/httpd-vhosts.conf as well.
I restored the original
httpd* files from the
/etc/apache2/original folder, and I restored the
/etc/hosts file to its original state.
apachectl configtest gives me:
httpd: Could not reliably determine the server's fully qualified domain name, using <username>.local for ServerName Syntax OK
So what do I do? How can I get my computer to stop refusing the connection? I don't know much about networking or servers.
For completeness, here's the original telnet error:
$ ssh localhost $ telnet localhost 9000 Trying ::1... telnet: connect to address ::1: Connection refused Trying 127.0.0.1... telnet: connect to address 127.0.0.1: Connection refused Trying fe80::1... telnet: connect to address fe80::1: Connection refused telnet: Unable to connect to remote host
## # Host Database # # localhost is used to configure the loopback interface # when the system is booting. Do not change this entry. ## 127.0.0.1 localhost 255.255.255.255 broadcasthost ::1 localhost fe80::1%lo0 localhost
and the Hadoop error which uses the same "connection refused" language as telnet:
java.net.ConnectException: Call From <username>.local/<ip> to localhost:9000 failed on connection exception: java.net.ConnectException: Connection refused; For more details see: http://wiki.apache.org/hadoop/ConnectionRefused
Following the link in the error (http://wiki.apache.org/hadoop/ConnectionRefused), I read the following:
If the application or cluster is not working, and this message appears in the log, then it is more serious.
- Check the hostname the client using is correct
- Check the IP address the client is trying to talk to for the hostname is correct.
- Make sure the destination address in the exception isn't 0.0.0.0 -this means that you haven't actually configured the client with the real address for that service, and instead it is picking up the server-side property telling it to listen on every port for connections.
- Check that there isn't an entry for your hostname mapped to 127.0.0.1 or 127.0.1.1 in /etc/hosts (Ubuntu is notorious for this)
- Check the port the client is trying to talk to using matches that the server is offering a service on.
- On the server, try a
telnet localhost <port>to see if the port is open there.
- On the client, try a
telnet <server> <port>to see if the port is accessible remotely.
None of these are Hadoop problems, they are host, network and firewall configuration issues. As it is your cluster, only you can find out and track down the problem.
and indeed I fail on the second-to-last step, which apparently should work; hence this question.