My goal is to VPN from my iPhone into my home network for iTunes Home Sharing on my Windows 7 machine. I've read that a regular VPN will not be compatible with the Bonjour protocol that Home Sharing uses. I found multiple solutions to this problem but they require that the iTunes library be hosted on a Mac.
It seems like there's two ways to go about this (aside from porting the iTunes library to Mac):
1.) Find a product that sets up a VPN configured to allow Bonjour and is compatible with the iPhone (Hamachi doesn't have iPhone support).
2.) Discover how to manually tweak a VPN to allow multicast Bonjour.
I've searched pretty extensively for both items and have nothing.
My router is a Linksys WRT54GL running Tomato 1.28
It's certainly tricky. AFAIK you're not exactly spoilt for choice WRT apps for mirroring remote iTunes share broadcasts on iOS. You'll also have a job getting your VPN to route multicast packets (not sure if you're using IPSec or PPTP).
The easiest solution I can think of is to run your own DNS server on your home network (if you're not doing so already) and insert TXT records pointing to your machine running iTunes (PC or Mac, it doesn't matter). For example in dnsmasq you'd add an entry similar to this:
txt-record=_daap._tcp.example.com
Where example.com is your home network's domain. Try using the Bonjour Browser app to see if mDNS services from your home domain (well, from your home domain DNS server) appear when you're on the road.
It's an imperfect solution but short of writing an iPhone app or spending ages on some crazy VPN configuration I think Wide-Area Bonjour is your best bet.