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I've recently inherited an infrastructure where all the users go through an AWS ELB -> nginx proxy -> AWS ELB -> Apache. The problem I'm seeing is that the client's IP is showing twice in Apache, a line similar to this:

"x.x.x.x, x.x.x.x" - - [26/Oct/2016:18:59:10 +0000] "GET /....

nginx's access log for this virtual host is fine and dandy:

x.x.x.x - - [26/Oct/2016:18:59:10 +0000] "GET /

The problem is that I'm not really sure how to debug where this gets lost. I assume it's either the headers nginx is sending or something weird in Apache, although I suspect it is the X-Forwarded-For headers that nginx is passing. Here's the relevant virtual host configuration for an affected domain:

location / { if ($xxx-example-com-maintenance) { return 503; } if ($http_origin ~* (https?://xxx\.example\.com)) { add_header 'Access-Control-Allow-Origin' "$http_origin"; } proxy_set_header Host $http_host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_pass $upstream;

Now, Apache's log format looks like this:

LogFormat "\"%{X-Forwarded-For}i\" %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-agent}i\" SESSION-%{frontend}C %h" forwarded

The latter was copied from the previous web stack and worked just fine. Kinda stuck here because it all looks good from my perspective. I did find nginx real_ip_header and X-Forwarded-For seems wrong however I'm running nginx 1.10. Apache version is 2.4.23. Any insights on how to troubleshoot this further would be appreciated. Thanks in advance.

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It turns out that X-Forwarded-For header is meant to behave like that and the solution was to use a different header that the ELB wasn't using - in my case X-Real-IP. I'm now able to see a single IP in the logs.

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