Bypass proxy server for https

[Guest]

We have Windows XP machines set up to run Microsoft Store Operations POS
systems with generic users on a LAN. The credit card service that integrates
with the POS system is set up to communicate directly from each machine over
the LAN to internet with secure access to the credit card authorization
service.

Generic users are not allowed to surf the web, so are blocked by the proxy
server. The network firewall is set to allow direct connections to the
secured site and we know that we can connect with generic users logged onto
the machines by using the telnet command.

By using WireShark we've found that by clearing the IE proxy settings and
accessing the secured site using IE the proxy server is bypassed, but when
running the credit card application it is directed to the proxy server. The
software vendor claims that the software does not direct the connection to
use a proxy server. The software was created in Visual Basic.

So far we have cleared the proxy settings in IE, cleared all plain text
references to the proxy server in the registry and in files, ran proxycfg and
cleared proxy settings, checked gpedit.msc to verify that is set to not use
the proxy server and cleared all proxy references in Microsoft Shared
Computer Toolkit for the user on the machines where that is used.

Where else could Window XP be pulling the directive to use the proxy server?

Thanks.

 

[Gary]

Where does your default gateway in the ip settings point?