To configure Internet remote access for users who are geographically apart, you require Citrix NetScaler Gateway integrated with Citrix StoreFront to provide remote access to published applications and desktops.
Citrix has been doing this from a long time now. Initially, Citrix made use of its software based product called Citrix Secure Gateway, which was then changed to a more robust hardware appliance called Citrix Access Gateway.
However, all customers couldn't take advantage of Citrix Access Gateway due to its high cost as compared to the software version of Citrix Secure Gateway, which actually came free with the XenApp Enterprise license.
Due to customers' growing needs and demands, Citrix soon released a virtual appliance for Citrix Access Gateway commonly known as the CAG VPX appliance, which was later included as a feature in NetScaler ADC appliances. You can also opt for the NetScaler Gateway VPX appliance.