credit card gateway not being able to contact store?

I added the credit card gateway half a year ago. It has been working until recently.

What happened was that when a customer confirms an order, zen cart sends info to the credit card gateway, they respond back but fail to postback on my zen cart. The results are the credit card transaction does not show up in the zen cart admin panel, and after customer sees "order is being processed..." a blank screen returns. (The customer winds up with a blank page after paying and wondering if the transaction has gone through.)

I found in another thread talking about port 1129 not being open. I checked and found that my server gateway comcast firewall is off, and my ubuntu firewall is inactive. So there is nothing blocking ports. I went further to enable the ubuntu firewall while allow-ing port 1129. this does not fix any problem. At the same time, this site http://www.yougetsignal.com/tools/open-ports/ still says my 1129 port is closed.

I am unable to get any help from the ubuntu forum and am still unsure if the problem is Linux, or zen cart, or even the modem.

Anybody can help?

Sometimes it's that the payment gateway changes how it works (usually though after lots of notice).

Even when it's not, a precise understanding and experience of the requirements and approach used by the specific gateway is usually needed to help, but as you haven't said which payment gateway you're using it's difficult to advise further.

Without you giving any useful details to go on, I'm only guessing, but I'd guess the following ...

1. You're using an old version of Zen Cart which is vunerable to hacks, and haven't at least patched it, or better yet, upgraded it to a secure version.

2. You need to use the debug tool that records the errors happening when the page is blank: https://www.zen-cart.com/tutorials/index.php?article=82

3. You need to recover from being hacked: http://www.zen-cart.com/wiki/index.php/Recovering_From_Hacks

1, the payment gateway i use is NMI.
2, I use the very same NMI code on 2 sites: older version (1.3.7.1, db patch 1.3.7.1) works fine, problem is on the newer version (1.3.8a db patch 1.3.8). The older version of zen cart is running on a shared server (hostgator).

Is port 1129 open required for my credit card processing?

Last time the credit card processing worked was on 9/15.

I went through all my files in /includes and admin/includes, other then the 4 plugin files from the credit processing, only these files have newer date stamps:

application_top.php (I added the lines to prevent hacks according to the wiki page.)

I installed email exporter after 9/15, which seems to be working fine and I suppose this does not have anything to do with the problem?

I do have 0-byte file empty.txt in all my "classic" folders which I assume is for the classic template that I am not using. These files are also dated 1/21 when I install the zen cart.

I have not touched the modem/gateway, other than rebooting the server on 9/10 (before 9/15 on which the problem did not exist).

The most likely suspect becomes the hack-prevention code I added?

w2e:

Is port 1129 open required for my credit card processing?
I don't know about NMI. The only module I know requires port 1129 is the Linkpoint/FirstData module.

w2e:

Last time the credit card processing worked was on 9/15.So, when did you last personally do a checkout from start to finish? Are any error messages displayed? What does it tell you on the checkout-success screen?

w2e:

application_top.php (I added the lines to prevent hacks according to the wiki page.)If done correctly and if your payment module is compatible, that shouldn't be any problem.
w2e:

I installed email exporter after 9/15, which seems to be working fine and I suppose this does not have anything to do with the problem?Should be unrelated.
w2e:

I do have 0-byte file empty.txt in all my "classic" folders which I assume is for the classic template that I am not using. These files are also dated 1/21 when I install the zen cart.Normal.
w2e:

I have not touched the modem/gateway, other than rebooting the server on 9/10 (before 9/15 on which the problem did not exist).You host this server out of your home?

the hacking code it is!

removed it and everything is back to normal!

Now which part of this hack prevention code I should modify to work with my 1.3.8a version?

None. You should really update the payment module to work more securely.