I am stuggeling with port 9000: Connection refused
error.
I work on Ubuntu 14.04
and faced the problem when trying to run Hadoop
in a non-distributed mode, as a single Java process (compare Hadoop 2.4.1 documentation). I tried to follow Hadoop Wiki suggestions on this error (hadoop/ConnectionRefused) but I did not succed (I am a beginner Ubuntu
user and find it difficult even to 100% understand the suggestions given). I posted a stackoverflow question from which I conclude that I have some general problem with port 9000 Connection
.
telnet output:
martakarass@marta-komputer:~$ telnet localhost 9000
Trying 127.0.0.1...
telnet: Unable to connect to remote host: Connection refused
nmap output:
martakarass@marta-komputer:~$ nmap localhost
Starting Nmap 6.40 ( http://nmap.org ) at 2015-04-27 11:09 CEST
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00022s latency).
Not shown: 995 closed ports
PORT STATE SERVICE
22/tcp open ssh
139/tcp open netbios-ssn
445/tcp open microsoft-ds
631/tcp open ipp
902/tcp open iss-realsecure
Nmap done: 1 IP address (1 host up) scanned in 0.08 seconds
Netcat configuration:
I tried to make use of the following command to force the 9000 port to be open:
nc -k -l 9000
but it did not work well (I was still not able to perform the standlone operation mentioned and linked above).
Judging from my google research results, I see that the problem is quite common and poses a huge struggle especially for those who are not good at "admin-job-related issues". As I belong to those, I kindly ask for answers to the following questions:
Q1: What is the origin of such problem in general? (Some for a layman introductory words / references about basic issues connected to ports / connections etc. would be very very welome).
Q2: How to deal with this problem?
Update.
sudo netstat -nlp | grep :9000
returns nothing.
sudo netstat -nlp | grep :9000
to your question.netstat
output, the most likely explanation is that the hadoop process has either failed to start, or is not listening on port 9000.sudo kill $(sudo lsof -t -i:9000)
afterwards everything was ok") does not work in mine case (in my casesudo lsof -t -i:9000
reports nothing).