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Old 12-29-2014, 10:48 AM   #1
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question on debugging network stack on CentOS 6.5 machine


I've recently installed CentOS 6.5 on a laptop at home to do some Openstack experimentation. (The setup includes downloading and running a Devstack setup). The install includes a dashboard I should be able to connect to with a browser running on my MAC. This connection fails. If I try telneting to the same IP/port I get:

MacBook-Pro:C fxp$ telnet 80 Trying telnet: connect to address Connection refused telnet: Unable to connect to remote host

On the host I see via netstat that httpd is listening on The firewall INPUT filter looks ok.

I'm looking for some debug commands I can use on the host to see what happens to these packets after arrival.

Old 12-29-2014, 02:45 PM   #2
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As you started the services that make up Devstack, is there anything odd in daemon or service logs?
Can you access the dashboard from the Devstack box itself? As in 'curl -I'?
Is SELinux enabled? If so does /var/log/audit/audit.log show something?
Is there any other port on the Devstack box you can successfully test from your MacBook?
What does 'iptables-save' return?
Old 01-30-2015, 11:32 AM   #3
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Hi all,

I finally got back to this recently. Turns out the problem was an entry in the INPUT chain of iptables. I took a closer look at iptables after running tcpdump and seeing that the server was generating ICMP host prohibited responses.



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