opkg install pptpd kmod-mppe

== /etc/pptpd.conf ==

#debug
option /etc/ppp/options.pptpd
speed 115200
stimeout 10
localip 192.168.11.1
remoteip 192.168.11.40-49

== /etc/ppp/chap-secrets ==

#USERNAME PROVIDER PASSWORD IPADDRESS
jason * testypass *

== /etc/firewall.user ==

# This file is interpreted as shell script.
# Put your custom iptables rules here, they will
# be executed with each firewall (re-)start.
# Allow all traffic in and out of the ppp interface. No reason to specify nets.
iptables -A input_rule -i ppp+ -j ACCEPT
iptables -A output_rule -o ppp+ -j ACCEPT
# This rule will allow traffic towards internet
iptables -A forwarding_rule -i ppp+ -j ACCEPT

== /etc/config/firewall ==

config 'rule'
option 'target' 'ACCEPT'
option '_name' 'pptpd'
option 'src' 'wan'
option 'proto' 'tcpudp'
option 'dest_port' '1723'

PPTP Cleint on OpenWRT: http://vpnonline.pl/en/konfiguracja/openwrt-pptp

Make localip/remoteip network different than LAN of the server to have access to entire LAN from PPTP Client.

Additionaly you need add route on PPTP Client fo LAN:

route add -net <LAN on PPTP server side> netmask 255.255.255.0 pptp-interface

Example:

route add -net 10.0.6.0 netmask 255.255.255.0 pptp-interface

If service not started automatically:

/usr/sbin/pptpd