Detecting proxies

anonymous proxies

[mactac]

I am trying to find a method of detecting anonymous proxies (I don't terribly about getting the actual IP address, but it would be nice)

I am aware of the IP environment variables, and they will show transparent proxies or "nice" proxies, but they won't show for anons.

I've heard that it can be done in java, but cannot find the actual methos/sample code. does anyone have this?

Are there any other methods of detecting that the user is using a proxy?

[anallawalla]

Using a proxy versus using an anon proxy can be tricky unless you can make assumptions that the ip address must be within the same C class.

In some cases I test for:

PC's IP: $ENV{'REMOTE_ADDR'}
Real address: $ENV{'HTTP_X_FORWARDED_FOR'}
Proxy: $ENV{'HTTP_VIA'}

I am not sure what has changed out there but for the past two years I haven't seen the last two fields populated but older messages show the following:

PC's IP: ****.xx.69.93
Real address: xxx.xx.69.74
Proxy: 1.1 proxy3.syd.xxxx.net.au:8080 (Squid/2.4.STABLE6)

This doesn't always catch transparent proxies. I would also expect the anonymiser sites to be changing IP addresses regularly.

[blaze]

Interesting question though - can you use java or javascript to assist in detecting a proxy?

If they are executed on the client side (before the proxy) you might be able to send some kind of information back.

[GeorgeGG]

Get stuff like this regular:

Date : 05/20/04 20:46:34
Host : cache2-2.ruh.?.net.?
IP :?.138.47.12
HTTP_VIA: 1.0 ADSL2 (NetCache NetApp/5.5R5), 1.0 cache2.ruh
HTTP_X_FORWARDED_FOR:?.116.213.72
HTTP_CLIENT_IP:?.100.193.19

Also if client has JavaScript enabled, usually can pickup
the referrer which can also give other info.

GeorgeGG

[anallawalla]

How does one test HTTP_CLIENT_IP?

Returns blank for me.

[upside]

I recently posted in another thread about using a Perl module to detect proxies. See:

[webmasterworld.com...]

[GeorgeGG]

I use:
$ENV{'HTTP_CLIENT_IP'}

Most all that are set come from one area.

GeorgeGG

[blaze]

Truly anonymous proxies do not forward such information, which I believe is what the original poster is concerned about.

[mactac]

any more info on this? Does anyone know how to do this in Java (NOT javascript, which cannot do it)