Learn how to install a windows compatable PPTP VPN server on FreeBSD.
Instructions for using POPTOP with MPPE 128bit encryption
1. Install poptop from the ports directory
[root]# cd /usr/ports/net/poptop
[root]# make install clean
This will download and install the latest version of PoPToP

2.Edit the configuration files
** My local network in this example is 172.16.0.0/16. You will need
to change the IP Address to meet your needs

/usr/local/etc/pptpd.conf
----------------------------------------------------------------
debug
nobsdcomp
proxyarp
localip 192.168.0.1
remoteip 192.168.0.2-255
pidfile /var/run/pptpd.pid
+chapms-v2
mppe-40
mppe-128
mppe-stateless

/etc/ppp/ppp.conf
---------------------------------------------------------------
loop:
set timeout 0
set log phase chat connect lcp ipcp command
set device localhost:pptp
set dial
set login
# Server (local) IP address, Range for Clients, and Netmask
# if you want to use NAT use private IP addresses
set ifaddr 192.168.0.1 192.168.0.2-192.168.0.255 255.255.255.0
add default HISADDR
set server /tmp/loop "" 0177

loop-in:
set timeout 0
set log phase lcp ipcp command
allow mode direct

pptp:
load loop
disable pap
# Authenticate against /etc/passwd
enable passwdauth
disable ipv6cp
enable proxy
accept dns
enable MSChapV2
enable mppe
disable deflate pred1
deny deflate pred1
set dns 24.26.163.24
set device !/etc/ppp/secure

/etc/ppp/secure
---------------------------------------------------------------
#!/bin/sh
exec /usr/sbin/ppp -direct loop-in

/etc/ppp/ppp.secret
---------------------------------------------------------------
#user #passoword
user1 password
user2 password

3. Ensure IP Forwarding is enabled
[root]# sysctl net.inet.ip.forwarding
1

If the value is not 1 you can enable ip forwarding by
[root]# sysctl net.inet.ip.forwarding=1

You can have it always default to 1 by editing
/etc/rc.conf
gateway_enable="YES"

4. Enable proxy arp
/etc/rc.conf
arpproxy_all="YES"

5. Start pptpd
/usr/local/etc/rc.d/pptpd start

Verify that it start successfully
[root]# netstat -a -n
tcp 0 0 0.0.0.0:1723 0.0.0.0:* LISTEN

PPTP uses tcp port 1723 and protocol 47 (GRE)
If you have a firewall in front of the VPN server make sure
you open the appropriate port

gateway_enable="YES"
arpproxy_all="YES"
pptpd_enable="YES"
pptpd_flags="-c /usr/local/etc/pptpd.conf -o pptp"
openvpn_enable="YES"
openvpn_configfile="/usr/local/etc/openvpn/server.conf"
pf_enable="YES"
nginx_enable="YES"
natd_enable="YES"
natd_interface="re0"
firewall_enable="YES"
firewall_type="OPEN"
firewall_logging_enable="YES"

ipfw add allow all from any to any
ipfw add divert natd ip from any to any via em0