Virtual Private Network (VPN)
The pfSense software offers three options for VPN connectivity, IPsec, OpenVPN, and PPTP.
IPsec allows connectivity with any device supporting standard IPsec. This is most commonly used for site to site connectivity to other pfSense installations, other open source firewalls (m0n0wall, etc.), and most all commercial firewall solutions (Cisco, Juniper, etc.). It can also be used for mobile client connectivity.
OpenVPN is a flexible, powerful SSL VPN solution supporting a wide range of client operating systems.
PPTP was a popular VPN option because nearly every OS has a built in PPTP client, including every Windows release since Windows 95 OSR2. However, it's now considered insecure and should not be used.
Limitations: Because of limitations in pf NAT, when the PPTP Server is enabled, PPTP clients cannot use the same public IP for outbound PPTP connections. This means if you have only one public IP, and use the PPTP Server, PPTP clients inside your network will not work. The work around is to use a second public IP with Advanced Outbound NAT for your internal clients. See also the PPTP limitation under NAT on this page.