You state you wish to use some sort of AAA authentication in order to authenticate against your domain credentials, but you have configured the VPN to use local client authentication without supplying it with a username and password, such as:
vpdn username cisco password cisco
The following link should get you started with enabling AAA for PPTP VPN:
Having re-read your original post, I have a few further thoughts as to why it will not work. You do not need to open 1723 and 500 on the pix, your vpdn configuration allows pptp to bypass conduit/acl checks when it is enabled (the sysopt connection permit-pptp command). However, I think you do need to ensure you have permitted 1723 outbound (likely) and GRE (protocol 47) inbound (unlikely), and that you are using a 1-to-1 static NAT translation between your inside private address on your 172.16.0.0 network and (one of) your public address on your outside block.
If you only have PAT and are not able to configure a static NAT entry then I don't think it will work. The alternative would be to configure an NAT-T aware IPSEC VPN tunnel to the Pix using the Cisco VPN Client, which will happily work with PAT - details of how to configure this can be found here:
I did not expect that this is so critical or may be just critical for me. I have attached the config here. It worked pretty well when Linksys router was in place and just these issues after replacing with PIX. Unfortunately I dont have much time and I may have to revert back if this doesnt work in next few hours.
I am not sure if I am doing some basic mistakes here about the user authentication etc. When I enable logging, I am getting this message. PPTP: Call id 32975, no session
Can you please check the config and advise. I am looking at other solutions now. Right now I am not using any Cisco VPN client. I guess these are not free right?
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...