> Is it possible to log original IP addresses of client computers
> which use proxy servers to connect to my web server?
Yes, if the proxy sends it and if you believe what the proxy says.
Quote:> Currently I get only proxy IP address in my logs, but I remember
> that I read somewhere that it is possible to know the original
> requester's address...
The proxy may send an HTTP header (x-forwarded-for seems to be
conventional - the "x-" prefix shows you that it isn't a formal
standard) which reports the address from which it had been called.
You would then find HTTP_X_FORWARDED_FOR in the environment.
I would suggest this can be useful for informational purposes, or
for pre-filling in a form response field that the user might yet
want to correct for themselves. Using it as an essential part of
some scheme (e.g charging or access control) would seem inadvisable,
since it may be entirely missing, or even wrong, through no fault of
the end user.