The requirements for the functionality of a personal firewall with mobile computing on WLANs are multilayered. They also apply to the critical phases during the registration and sign-off process on the hotspot. Requirements must be known at the earliest possible time and should be in place from system start. They also must remain when no VPN connection exists or has been deactivated. Furthermore, the user should be safeguarded against arbitrarily reconfiguring or completely shutting off the personal firewall.

VPN client with integrated personal firewall

The dilemma of system requirements may be resolved by a VPN solution with a client-integrated personal firewall. The advantage of the integrated variant is that a personal firewall and VPN client are functionally linked to one another. In a quasi-teamwork fashion, the existing firewall rule statements are dynamically activated in dependence on the network environment. Fundamentally, three situations may be differentiated:

1. Known networks
2. Unknown networks
3. VPN networks


Automatic recognition of the network takes place by validating different network factors. In friendly networks, permissive firewall rules apply as they do in public environments like the hotspot. The personal firewall must work with intelligent mechanisms that guarantee a secure activation of network access via the browser, as well as a secure registration on the hotspot. The user chooses the menu point “hotspot registration” in the welcome area of a public WLAN. Subsequently, the VPN client automatically searches the hotspot and opens the web site for registration in a standard browser. For example, after successful entry of access data and activation by the operator, the VPN connection can connect to the company headquarters and communicate as securely as it would in an office.

In this manner, the PC is accessible in the WLAN in no time, and there are ports dynamically assigned for http/https for registration and logging off the hotspot. During this time, only data traffic is possible with the operator’s hotspot server. Unnecessary data packets are refused. In this way, it is guaranteed that a public WLAN can use the VPN connection at the central data network and no direct internet access can take place.

Inspection of security-relevant parameters

An additional important component of the implementation of company wide security directives for mobile computing on hotspots is central management of client software. With central security management, the administrator also fundamentally determines the client’s firewall rules. It can enforce adherence in which the user allows no on-site possibility of an intended or unintended change. Additionally, further security-relevant parameters such as the status of virus protection programs, operating system patch status, and software release of the VPN client must be inspected upon connection to the company network. Access to the productive network is only authorized after the clearance of all security risks.