Centos Port Forwarding

08 Jan 2016

Before I forget I had an issue with port forwarding a webapp from the base centos vm to my host through vagrant - the webapp was unresponsive and requests would eventually timeout. In the past the issue has always been starting the webapp listening on a non-“0.0.0.0” adapter but the webapp’s config is quite explicit that it is set to listen on the right one. A quick nestat test proved this:

$ netstat -o -n -a | grep 84 where the webapp is listening on 8484

  vagrant@localhost vagrant]$ netstat -o -n -a | grep 84
  tcp        0      0 0.0.0.0:58494               0.0.0.0:*                   LISTEN      off (0.00/0/0)
  tcp        0      0 0.0.0.0:8484                0.0.0.0:*                   LISTEN      off (0.00/0/0)
  unix  2      [ ACC ]     STREAM     LISTENING     10584  private/scache

That is not the problem then. Further investigation using sudo tcpdump -i any not port 22 showed requests coming in and yet no response in the browser.

The issue turns out to be that the base centos image has iptables set up to stop it.

sudo iptables -F resolved it and now outbound responses are routed back.

Note that this does not affect a base Ubuntu image.

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