server crash - how do I investigate the issue?

Question

What is the correct way to diagnose the problem? or get to the bottom of the crash?

I've ubuntu server.

It crashed out of blue. I couldn't connect to ssh it was refusing connection. And all services except apache were down.

I tried to look at /var/log/ but couldn't find anything useful.

score 0 · Accepted Answer · answered Oct 21 '11 at 15:13

0

did you make changes at an iptables firewall or another firewall? The "all services down" effect often comes from that. If so and you still have access to your server you can flush the iptables settings:

sudo iptables -F INPUT
sudo iptables -P INPUT ACCEPT

Do it only if you are sure that you want to reset your firewall config. ACCEPT everything is the default firewall config. You may wish to show the INPUT rules before by invoking:

sudo iptables -L INPUT

All those commands can as well be done with the chain OUTPUT instead of INPUT. Default is all Chains empty and all ACCEPT.

Greetings from Switzerland, Michael

answered Oct 21 '11 at 15:13

Michael K

13,888

Ah what you didnt mention: is the problem still present after a reboot? – Michael K Oct 21 '11 at 15:14
nope, after reboot I got in. So that excludes firewall.
With services down, I meant subsonic/deluge/java wasn't functionaing + ssh, I could see mysql/php/apache running fine though.
– Oct 21 '11 at 15:33
Is it reproducible? – Michael K Oct 21 '11 at 15:37

server crash - how do I investigate the issue?

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