Unfortunately VPN interfaces I am observing here don't expose any definite type in ifr_hwaddr.sa_data (having ARPHRD_NONE). But the flags from SIOCGIFFLAGS have IFF_POINTOPOINT for such interfaces, so it is probably nothing wrong in guessing the iface type as PPP if the flag is set.
Fixes Creativerse hanging on creating local game when there is a VPN interface.
-- v2: nsiproxy.sys: Detect PPP interface type from flags on Linux.