Apache HTTP Log + X-Forwarded-For

We use HTTP (Apache) behind F5 Application Firewall (or Reverse Proxy ... blah blah),

F5 IP = 10.0.0.1
Client = 100.100.100.100

So when we check Common log, we find

10.0.0.1 - - [22/Jul/2008:11:33:15 +0700] "GET /index.html HTTP/1.1" 304 -


that doesn't show IP from client, It show F5's IP

httpd.conf file:

LogFormat "%h %l %u %t \"%r\" %>s %b" common

We need "X-Forwarded-For" variable on Apache Log.

So, modified httpd.conf file:

LogFormat "%h %l %u %t \"%r\" %>s %b \"%{X-Forwarded-For}i\"" common

Check log again access_log (common)

10.0.0.1 - - [22/Jul/2008:11:41:49 +0700] "GET /index.html" 200 1685 "100.100.100.100"

...
Enjoy!