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I'm running nginx 1.2.6 behind amazon elb.

Periodically I see the following lines in nginx access.log:

10.28.135.252 - - [14/Jan/2013:14:20:07 +0000] "-" 400 0 "-" "-" "-"
10.28.135.252 - - [14/Jan/2013:14:20:07 +0000] "-" 400 0 "-" "-" "-"
10.28.135.252 - - [14/Jan/2013:14:20:14 +0000] "-" 400 0 "-" "-" "-"
10.28.135.252 - - [14/Jan/2013:14:20:14 +0000] "-" 400 0 "-" "-" "-"
10.28.135.252 - - [14/Jan/2013:14:20:18 +0000] "-" 400 0 "-" "-" "-"
10.28.135.252 - - [14/Jan/2013:14:20:48 +0000] "-" 400 0 "-" "-" "-"

There are no errors in the error log. What can it be?

Thanks.

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Is 10.28.135.252 the IP of the server running nginx? –  Mike Mackintosh Jan 14 '13 at 14:32
    
No. Its most probably the IP of ELB, because health checks originate from the same IP. –  Zaar Hai Jan 14 '13 at 14:39
1  
This could be caused by a user/request that has clicked on a link on your website and download some content. If the user cancelled the request halfway the log might generate the 400 0 "-" "-" "-" lines. This can be simulated by starting a telnet session to your host e.g telnet hostname 80 and then CTRL+D to terminate the connection prematurely. Keep the log file open using tail -F /var/log/nginx/yourlogfile.log while you are testing with telnet. You should not be worried about these warnings though. –  val0x00ff Jan 14 '13 at 15:27
    
Yes. the simulation worked. I guess this lines are left by ELB. –  Zaar Hai Jan 14 '13 at 17:12

1 Answer 1

up vote 3 down vote accepted

This occurs when a client connects to the web server, but then fails to send a request before disconnecting. It also occurs when a client connects, sends a request with Connection: Keep-Alive set, but disconnects before sending another request. In either case, they can be safely ignored.

share|improve this answer
    
Its clear. Thanks. I guess its ELB specific behavior. –  Zaar Hai Jan 14 '13 at 17:09
    
It happens outside of EC2 as well. There's not really anything you can do about it. –  Michael Hampton Jan 14 '13 at 17:10

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