Authenticate to multiple backend AD servers

[DervMan]

I'm in the situation where I'd like to provide VPN (IPSec) connectivity to around 100 sites each with their own AD domain. The easiest option would be a PFSense box for each site but that's very inefficient. Ideally PFSense would 'route' the authentication request dependant on the username (assuming they specify the domain name).

Anyone know if PFSense can authenticate to multiple backed AD domains?

Someone who logins with domain1\user1 would have the authentication request sent to the DC for domain 'domain1'

Whereas the login domain2\user1 would have the authentication request to the DC for 'domain2'

Thanks