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I am trying to host a Shiny R Web Server on a CentOS Virtual Machine. I am troubleshooting some networking issues, but I want to confirm that the port is open.

I have a Static IP address for this Virtual Machine, but when I navigate to Static_IP_Address:3838/ , the connection times out. So, is Port 3838 open?

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Update: Here is the outcome of nmap: enter image description here

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Gary
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3 Answers3

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The above cannot tell you whether the port is open, only whether there is anything listening on that port. And there is, as you can see from the first line, which laso identifies the program listening as shiny-server, as per your desire.

The command to see whether the firewall is guarding the port is nmap.For instance, 

# nmap -p80 192.168.73.96

  Starting Nmap 6.40 ( http://nmap.org ) at 2015-11-30 15:50 CET
  Nmap scan report for d2.my.lan (192.168.73.96)
  Host is up (0.00052s latency).
  PORT   STATE  SERVICE
  80/tcp closed http
  MAC Address: 08:00:27:18:F9:44 (Cadmus Computer Systems)

  Nmap done: 1 IP address (1 host up) scanned in 0.51 seconds

In your case substitute 3838 in the command to 80. Closed means there is no program listening on it, while you are hoping to find open. There are several other possibilities.

Most likely, you are having a routing problem. You should look at your routing table, and see whether it can reach your VM.

MariusMatutiae
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For posterity purposes, I wanted to post an answer to how I finally got my Shiny Server up and running.

  1. I disabled iptables:

/etc/init.d/iptables save

/etc/init.d/iptables stop

chkconfig iptables off

  1. I changed /etc/shiny-server/shiny-server.conf to listen on Port 8080 instead of Port 3838. On Port 3838, I could not access the web application from any other computer on the network. But from Port 8080, I could.
Gary
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I experienced the same issue, but for me the solution was with the internal firewall of Centos 7, so I enabled it, and restart:

#firewall-cmd --permanent --zone=public --add-port=3838/tcp
#firewall-cmd --reload

found the answer on the centos forum working with different ports, source: https://forums.centos.org/viewtopic.php?f=47&t=57945

RolandoAmir
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