Client-IP HTTP header to X-Forwarded-For

Mike lists.accounts at
Thu May 3 23:35:29 MSD 2007

Igor Sysoev wrote:
> On Thu, May 03, 2007 at 06:07:37PM +0100, Mike wrote:
>> Igor Sysoev wrote:
>>> On Thu, May 03, 2007 at 03:31:44PM +0100, Mike wrote:
>>>> Client requests are through virtual IP's that are handled by a hardware 
>>>> load balancer, and then passed onto the real servers on the backend. The 
>>>> source IP from the client is NAT'd so that all IP's appear to originate 
>>> >from the load balancer. Responses from the real servers are sent back 
>>>> via the load balancer to the client.
>>>> On the load balancer, I have enabled, in the configuration, that a 
>>>> header be added by the load balancer and passed onto the server that is 
>>>> running Nginx (version 0.5.19). The request header that is added and 
>>>> passed out to the real server, is as follows:
>>>> Client-IP: myip
>>>> Is there any way to get Nginx to log this IP as the remote_addr or as 
>>>> X-Forwarded-For so that the PHP application that Nginx is passing 
>>>> requests to will log the real source IP? I realise that there have been 
>>>> posts in the past but I have not been able to figure this out.
>>> This header is available in nginx as $http_client_ip.
>>> You can describe it in log_format instead of $remote_ip
>>> and you pass it to FastCGI:
>>> fastcgi_param  REMOTE_ADDR        $http_client_ip;
>> Hi Igor
>> Thanks for the fast and accurate response.
>> I did a search against the $http_client_ip string on the wiki and 
>> nothing showed up, so unless anyone has any objections, I'll add this 
>> with my use-case scenario.
> All client headers are available as $http_... variables.
> For example, "X-Strange-Header" as $http_x_strange_header.

Ahh, I understand now. Maybe I'll add an example to the "Example 
Configurations and Recipes" section, just in case anyone else is in a 
similar situation.

Thanks again,


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