SAProuter is a standalone SAP program that protects your SAP network against unauthorized access. SAProuter acts as a proxy in a network connection between SAP systems, or between SAP systems and external networks.
SAProuter controls the access to your network, acting as an application gateway. As such, it is a useful enhancement to an existing firewall system (which acts as a port filter).
The firewall acts as an impenetrable wall around your network. However, since particular types of connections need to penetrate this wall, a "hole" (i.e. a port) has to be opened in the firewall. SAProuter assumes the control of this hole, providing you with the means of controlling access to your SAP system.