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 Post subject: Linode High CPU Usage
PostPosted: Sat Sep 27, 2014 10:31 am 
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Senior Newbie

Joined: Sat Sep 27, 2014 10:01 am
Posts: 6
Hi,

Since yesterday I have been receiving high cpu usage alert from Linode up to 196%. Normally it is limited to 20% only.

I have linode 2GB plan.

Now I am unable to figure out what's the issue. It's causing my blog traffic to all time low.

Image
Image

System Load : 7.71

Tried to Reboot, Restarted Php5-fpm and Nginx.

Any idea how to resolve this?


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PostPosted: Sat Sep 27, 2014 12:34 pm 
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Joined: Sun Mar 07, 2010 6:47 pm
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Website: http://www.rwky.net
Location: Earth
Your htop graph shows PHP is using most of the cpu, check your web server access logs see if you're being crawled by a bot or something more malicious.

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PostPosted: Sat Sep 27, 2014 12:56 pm 
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Joined: Sat Sep 27, 2014 10:01 am
Posts: 6
Hi,

Thank you for the reply. Since I am a newbie, I don't know much about it. Any command to see log file?


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PostPosted: Sat Sep 27, 2014 2:04 pm 
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ICQ: 897607
Look in your server logs (probably /var/log/nginx/access.log) and see if there are lots of POST requests to /xmlrpc. If so, try googling for solutions. I'm not a php or wordpress guy so just learning about this myself... a client linode running wordpress was getting hammered yesterday and CPU usage was really high all day.


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PostPosted: Sun Oct 12, 2014 10:30 am 
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Joined: Wed Sep 03, 2014 2:00 pm
Posts: 13
Quote:
Look in your server logs (probably /var/log/nginx/access.log) and see if there are lots of POST requests to /xmlrpc. If so, try googling for solutions. I'm not a php or wordpress guy so just learning about this myself... a client linode running wordpress was getting hammered yesterday and CPU usage was really high all day.
THIS! I just had this happen the other week on a LAMP server that I had at another provider...CPU Usage was going nuts and was even higher then yours OP, turns out it was XMLRPC getting pounded, there's Wordpress plugins to disable it or you can disable access to it via nginx configuration/htaccess for apache.


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PostPosted: Mon Dec 29, 2014 8:20 pm 
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Joined: Thu Apr 03, 2014 7:16 pm
Posts: 5
I just had a similar problem to this today, and with research discovered that it indeed was due to a DOS xmlrpc attack. For now, I've added the following to the impacted site's .htaccess file, and it immediately fixed the problem, which was consuming all CPU resources even with all other traffic relatively low...

# begin fix for xmlrpc exploits
<Files xmlrpc.php>
Order allow,deny
Deny from all
</Files>
# end fix for xmlrpc exploits


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PostPosted: Wed Mar 04, 2015 6:22 am 
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Joined: Mon Apr 19, 2010 10:09 pm
Posts: 9
I have found that the allow,deny doesn't work in all cases and have opted to use a rewrite rule to point XMLRPC POST calls to 0.0.0.0 - this has helped with my high IO rates and CPU Usage immensely with Wordpress sites being attacked.
Code:
RewriteRule ^xmlrpc\.php$ "http\:\/\/0\.0\.0\.0\/" [R=301,L]


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PostPosted: Fri Jun 16, 2017 5:33 pm 
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Joined: Wed Oct 20, 2010 12:11 pm
Posts: 170
That would work if the OS was windows.


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PostPosted: Tue Jul 04, 2017 3:21 am 
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Joined: Wed Oct 21, 2015 6:35 pm
Posts: 3
Quote:
That would work if the OS was windows.
That is why the OP should check logs because it may be something similar but probably not identical.


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