What is MPD ?

Mpd is a netgraph(4) based implementation of the multi-link PPP protocol for FreeBSD.  It is designed to be both fast and flexible.
It handles configuration and negotiation in user land, while routing all data packets strictly in the kernel.  It supports several of
the numerous PPP sub-protocols and extensions, such as: Multi-link PPP capability, PAP, CHAP, MS-CHAP and EAP authentication ,
PPP compression and encryption, IPCP and IPV6CP parameter negotiation

Install and Configure MPD4

#cd /usr/ports/net/mpd4
#make install clean

Modify mpd.conf

#cd /usr/local/etc/mpd4
#pico mpd.conf
default:
        load client1
        load client2
client1:
        new -i ng0 pptp1 pptp1
        set ipcp ranges 10.100.100.1/32 10.100.100.10/32
        load client_standard

client2:
        new -i ng1 pptp2 pptp2
        set ipcp ranges 10.100.101.1/32 10.100.101.10/32
        load client_standard

client_standard:
        set iface disable on-demand
        set iface enable proxy-arp
        set iface idle 0
        set iface enable tcpmssfix
        set bundle enable multilink
        set link yes acfcomp protocomp
        set link enable no-orig-auth
        set link enable keep-ms-domain
        set link no pap chap
        set link enable chap
        set link yes chap-msv1 chap-md5 chap-msv2
        set link mtu 1460
        set link keep-alive 10 60
        set ipcp yes vjcomp
        set ipcp dns 8.8.8.8
        # set ipcp nbns 192.168.1.4
        set bundle enable compression
        set ccp yes mppc
        set ccp yes mpp-e40
        set ccp yes mpp-e128
        set ccp yes mpp-stateless

Modify mpd.links

#pico mpd.links
pptp1:
        set link type pptp
        set pptp self 10.100.100.1
        set pptp enable incoming
        set pptp disable originate
        set pptp disable windowing
        set pptp enable always-ack

pptp2:
        set link type pptp
        set pptp self 10.100.100.1
        set pptp enable incoming
        set pptp disable originate
        set pptp disable windowing
        set pptp enable always-ack

Modify mpd.secret

#pico mpd.secret
### user, pass & ip address ###
sentono 123456 10.100.100.10/32
testing testing123 10.100.101.10/32

### NOTE ###
## user sentono will receive a static ip 10.100.100.10
## user testing will receive a static ip 10.100.101.10

Modify rc.conf

#pico /etc/rc.conf

### add 2 lines below into rc.conf ###
mpd_enable="YES"
gateway_enable="YES" ## enable ip forwarding

Starting up mpd4

#/usr/local/etc/rc.d/mpd4 start

Ifconfig Result

#ifconfig
re0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=389b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,WOL_UCAST,WOL_MCAST,WOL_MAGIC>
        ether 00:1c:c0:83:d6:44
        inet 10.100.100.1 netmask 0xfffffff8 broadcast 10.100.100.107
        media: Ethernet autoselect (100baseTX <full-duplex>)
        status: active
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
        inet6 fe80::1%lo0 prefixlen 64 scopeid 0x2
        inet6 ::1 prefixlen 128
        inet 127.0.0.1 netmask 0xff000000
ng0: flags=88d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST> metric 0 mtu 1396
        inet 10.100.100.1 --> 10.100.100.10 netmask 0xffffffff
ng1: flags=88d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST> metric 0 mtu 1396
        inet 10.100.100.1 --> 10.100.101.10 netmask 0xffffffff
#

### NOTE ###
## Ifconfig result above is the result if 2 user connected into the vpn server at the same time.

We are finished configured the MPD4 vpn server next we need to configure VPN PPTP client in Windows XP.
Please click this link for configure VPN client in Windows XP How To Connect to the MPD4 VPN server From Windows XP