OpenCart on Nginx as reverse proxy causing login issue?

[cosmicx]

Hi! First time to post here in the Forum.

I've been testing VestaCP live using OpenCart. It has very little traffic and I encounter an issue as reported by a customer. Not sure if this is server/hosting related, but maybe I can get some help here to further investigate on the issue.

The issue reported to me:

When user go to the login page, the user and password field gets auto populated or auto filled, and eventually logs in. The account that get auto logged in wasn't really his account, but of some else's account.

How can I investigate on this issue? Someone says it might be a session issue. I looked at my /home/username/tmp directory and I just see tons of sess_ files. The directory has RW permission only by the VestaCP user.

Could this be a server related issue?

[noogen]

It's really hard to troubleshoot without you trying to figure out where the issue is first: is the problem with apache or nginx? The most important thing is know how to recreate the issue.

In this case, we have to make a couple of assumption or guesses and begin testing out the theory. Let assume that it is a caching issue.

1. Is is a problem at apache level? can we recreate the issue if you don't have nginx in front of apache? If not, it must be nginx.
2. If it is nginx, is it a proxy cache issue? Do you have setting to bypass cache for certain OpenCart session cookie name?