RFC1918 addresses to permit in for VPN?

Our DSUA filter had to have a small hole punched in since a customer had a VPN (I do not know yet as to what kind) which was receiving packets sourced at 172.17.x.x. Is this a misconfiguration on the sender's end, or a "feature." I think there was earlier discussion on VPN's requiring ICMP (echo?) -- http://www.internet.org.ph Internet and ISP's in the Philippines http://www.ASARproject.org Artists for Social Action and Response GSM Mobile: +63-917-810-9728