Hi Harrison,
We need a higher License on PIX 501 to do encryption for VPN, which is a required phase. The license you need is "3DES/AES and DES Encryption Licenses"
The base license provides the following:
-The Cisco PIX 501 10-user license supports up to 10 concurrent source IP addresses from
your internal network to traverse through the Cisco PIX 501.
-The integrated DHCP server supports up to 32 DHCP leases.
-It can not provide any type of encryption
You can get more details on Page 6 of the following document:
http://www.cisco.com/en/US/prod/collateral/vpndevc/ps5708/ps5709/ps2030/ps2031/product_data_sheet09186a0080091b18.pdf
Regards,
Khubaib
