I wish to write a mobile application to gain access to a database that's presently held on our LAN and utilized by a credit card applicatoin around the network. I understand will be able to open a port within our firewall to redirect the traffic in the mobile phone towards the database however i a worried about the safety.

What ways could I envisage to provide secure mobile accessibility database while still permitting access in the local network application?

Things I would do in cases like this is offer an interface like WCF (Relaxation/JSON/etc.) towards the database for the mobile customers. Eventually you can even convert to by using their for that LAN and also the web. The end result could be better still security throughout.

Here are a few good examples of methods to get this done:

Java Peaceful Web Services Guide - http://www.oracle.com/technetwork/articles/javase/index-137171.html

WCF Guide - http://msdn.microsoft.com/en-us/netframework/dd939784

Summary of Cleaning soap - http://www.w3schools.com/soap/default.asp

As Firebird provides numerous connectivity options (JDBC, .Internet, Python) you've got a lot of preference/versatility about how exactly you deploy your internet service interface. I'd consider AXIS if you're considering implementing with Java (http://axis.apache.org/axis/) or WCF if .Internet (http://msdn.microsoft.com/en-us/library/dd203052.aspx) Whether you opt for a Peaceful or Cleaning soap/XML-RPC interface is dependent largely on which functionality to you need to expose and also to whom. A public API that you would like to offer to some broad audience would most likely perform best like a Peaceful interface (think, Twitter, Flickr etc.) whether it would be a closed/proprietary interface you'd most likely go lower the Cleaning soap route. However, mobile application development frameworks are broadly better at consuming Peaceful web services than Cleaning soap in my opinion. With native apple iphone applications In my opinion you need to roll your personal Cleaning soap interface. A few of the application accelerator tools have both Cleaning soap and Relaxation client support.