All local IP addresses are masked during Internet access and assigned to the external IP of the Intra2net system (n:1 NAT / Masquerading). No NAT is performed just for IPs on networks with "LAN without NAT" mode (see Section 9.1, „IPs and Networks“).
Masquerading can confuse some protocols. The most important ones are corrected automatically by the Intra2net system:
Active FTP, PPTP, IRC, Quake, Cuseeme, Realaudio, Vdolive.
For those missing (e.g. ICQ or Gnutella) the Intra2net system has a Socks 5 proxy server on port 1080, which can be used by all clients with full access without an extra login. It simply requires activation under Services > Proxy > Socks.
For some protocols, it is also necessary to use the "Incoming Socks Connections Enabled" option in the firewall configuration for the relevant provider.