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GeoIP Module for Blocking IP in http_x_forwarded_for

Posted by anish10dec 
anish10dec
GeoIP Module for Blocking IP in http_x_forwarded_for
January 11, 2018 01:20PM
GeoIP module is able to block request on basis of remote address which is IP
of the remote device or user but not on basis of X-Forwarded-For IP if it
has multiple IP address in it.

There is Frontend Server( Server A) which receives the request and send it
to Intermediate Server (Server B)
We have GeoIP module installed on Intermediate Server i.e. Server B


Server B <--- Server A <---- User

When Server B , receives the request from Server A, remote address
(remote_addr) for Server B is IP of Server A.
Device/User IP is in http_x_forwarded_for field .
If http_x_forwarded_for has single IP in it GeoIP module is able to block
the IP on the basis of blocking applied.

If http_x_forwarded_for has multiple IP i.e IP of User as well as IP of some
Proxy Server or IP of Server A, then its not able to block the request.

Below is the configuration :

geoip_country /usr/share/GeoIP/GeoIP.dat;
geoip_proxy IP_OF_ServerA; // GeoIP module ignores remote_addr
considering it as trusted and refers to X-Forwarded For

map $geoip_country_code $allowed_country {
default no;
US yes;
}

http_x_forwarded_for = { User IP of UK } - Request from this IP is getting
blocked

http_x_forwarded_for = { User IP of UK , Proxy IP of US } - This request
is not getting blocked

http_x_forwarded_for = { User IP of UK , IP of Server A } - This request
is not getting blocked

It seems nginx GeoIP Module refers to Last IP in http_x_forwarded_for field
for applying the blocking method.

Is there a way to check for First IP Address in http_x_forwarded_for for
blocking the request ?

Please suggest

Please refer this for Solution in Apache
https://dev.maxmind.com/geoip/legacy/mod_geoip2/

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,278110,278110#msg-278110

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Maxim Dounin
Re: GeoIP Module for Blocking IP in http_x_forwarded_for
January 11, 2018 03:20PM
Hello!

On Thu, Jan 11, 2018 at 07:17:20AM -0500, anish10dec wrote:

> GeoIP module is able to block request on basis of remote address which is IP
> of the remote device or user but not on basis of X-Forwarded-For IP if it
> has multiple IP address in it.
>
> There is Frontend Server( Server A) which receives the request and send it
> to Intermediate Server (Server B)
> We have GeoIP module installed on Intermediate Server i.e. Server B
>
>
> Server B <--- Server A <---- User
>
> When Server B , receives the request from Server A, remote address
> (remote_addr) for Server B is IP of Server A.
> Device/User IP is in http_x_forwarded_for field .
> If http_x_forwarded_for has single IP in it GeoIP module is able to block
> the IP on the basis of blocking applied.
>
> If http_x_forwarded_for has multiple IP i.e IP of User as well as IP of some
> Proxy Server or IP of Server A, then its not able to block the request.
>
> Below is the configuration :
>
> geoip_country /usr/share/GeoIP/GeoIP.dat;
> geoip_proxy IP_OF_ServerA; // GeoIP module ignores remote_addr
> considering it as trusted and refers to X-Forwarded For
>
> map $geoip_country_code $allowed_country {
> default no;
> US yes;
> }
>
> http_x_forwarded_for = { User IP of UK } - Request from this IP is getting
> blocked
>
> http_x_forwarded_for = { User IP of UK , Proxy IP of US } - This request
> is not getting blocked
>
> http_x_forwarded_for = { User IP of UK , IP of Server A } - This request
> is not getting blocked
>
> It seems nginx GeoIP Module refers to Last IP in http_x_forwarded_for field
> for applying the blocking method.

This is what X-Forwarded-For header format assumes: IP addresses
are added to the end of the list. As such, the last address is
the only one you can trust in the above configuration.

That is, a request with

X-Forwarded-For: IP1, IP2, IP3

as got from Server A doesn't mean that you've got a request from
IP1 forwarded to you via various proxies. It instead means that
Server A got the request from IP3 with "X-Forwarded-For: IP1, IP2"
already present in the request. Nothing guarantees that IP1 and
IP2 are real addresses - they can be easily faked by the client,
or they can be internal addresses in the client network.

> Is there a way to check for First IP Address in http_x_forwarded_for for
> blocking the request ?

If you really want to, you can do so using the
geoip_proxy_recursive directive and configuring the geoip_proxy to
trust the whole world, see here:

http://nginx.org/r/geoip_proxy_recursive

Note though that this is generally not secure as the address can
be easily forged, see above.

--
Maxim Dounin
http://mdounin.ru/
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Jason Whittington
RE: [IE] GeoIP Module for Blocking IP in http_x_forwarded_for
January 11, 2018 04:50PM
If you control Frontend Server A I would suggest not using X-Forwarded-For for this purpose. Can you have the front end server send a distinct header to server B? X-Real-IP would be a good choice of header. Then Server B could key off that header instead of XFF.

You might find this page interesting:

https://distinctplace.com/2014/04/23/story-behind-x-forwarded-for-and-x-real-ip-headers/

Jason


-----Original Message-----
From: nginx [mailto:[email protected]org] On Behalf Of anish10dec
Sent: Thursday, January 11, 2018 6:17 AM
To: nginx@nginx.org
Subject: [IE] GeoIP Module for Blocking IP in http_x_forwarded_for

GeoIP module is able to block request on basis of remote address which is IP of the remote device or user but not on basis of X-Forwarded-For IP if it has multiple IP address in it.

There is Frontend Server( Server A) which receives the request and send it to Intermediate Server (Server B) We have GeoIP module installed on Intermediate Server i.e. Server B


Server B <--- Server A <---- User

When Server B , receives the request from Server A, remote address
(remote_addr) for Server B is IP of Server A.
Device/User IP is in http_x_forwarded_for field .
If http_x_forwarded_for has single IP in it GeoIP module is able to block the IP on the basis of blocking applied.

If http_x_forwarded_for has multiple IP i.e IP of User as well as IP of some Proxy Server or IP of Server A, then its not able to block the request.

Below is the configuration :

geoip_country /usr/share/GeoIP/GeoIP.dat;
geoip_proxy IP_OF_ServerA; // GeoIP module ignores remote_addr
considering it as trusted and refers to X-Forwarded For

map $geoip_country_code $allowed_country {
default no;
US yes;
}

http_x_forwarded_for = { User IP of UK } - Request from this IP is getting blocked

http_x_forwarded_for = { User IP of UK , Proxy IP of US } - This request is not getting blocked

http_x_forwarded_for = { User IP of UK , IP of Server A } - This request is not getting blocked

It seems nginx GeoIP Module refers to Last IP in http_x_forwarded_for field for applying the blocking method.

Is there a way to check for First IP Address in http_x_forwarded_for for blocking the request ?

Please suggest

Please refer this for Solution in Apache https://dev.maxmind.com/geoip/legacy/mod_geoip2/

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,278110,278110#msg-278110

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