Proxy servers and IPs

[potato95]

When I receive an order through my website the credit card company send a confirmation email with various details of the purchase including the IP address of the shopper.

However when I try to grep the server log files for this IP it is often missing. Why is this?

I am assuming it is something to do with proxy servers.

Can somebody explain.

Thanks.

[keyplyr]

Proxy? Possibly.

However, it's been my experience that, depending on the server config, access_logs can be way off, often missing up to a third of requests.

[potato95]

Thanks keyplyr. What causes logfiles to completely miss all info from a browser?

In my case it looks as though the IP changes between leaving our site and going to the payment processing site. I can grep the logs to find the individual ip of the person adding the product to the cart and going through the checkout but this is a different IP from that reported back fom the card processor. I don't really understand how a users IP can suddenly change.

[larryn]

potato,

Sometimes, if the user is going through a proxy server (AOL for instance), their proxy server might change due to the change in protocol from http to https (the secure protocol used at the credit card processing site).

You'd be better off using some type of tracking URL when you send the visitor to the other site.

Larry