I have an OperWRT router with OPenVPN and PPPD servers configured.Network topology is like follow:I have problem configuring PPPD to push routes B,C to A.Client A, when connected to router via PPPD, has access to D, but not to B/COn the other side machines on D network has access to B and C without any extra configuration.Right now I add static route on client with route add ... command, but this is inconvienent. 
PPPD access to networks behind router
routing;openvpn;pppd
The only option that exists inside pptp(Client) is to enforce default route through ppp server: And at the server there is no way to push routes the same way it can be done using an OpenVPN server. Microsoft KBTaking a look at the How VPN Works page from Microsft it explicitly says that you will need to rely on other protocols(like RIP) to create dinamic routng environment:Dynamic RoutingBy implementing a dynamic routing protocol, such as RIP or Open Shortest Path First (OSPF), administrators can configure routers to exchange routing information with each other as needed.If Linux is client, this is a solution: It is distribution dependent, but on CentOS(depending on version being used) you can create the file /etc/ppp/ip-up.local or /etc/ppp/ip-up with the following contents:#!/bin/bash/sbin/ip route add 192.168.10.0/24 via 192.168.1.1/sbin/ip route add 192.168.20.0/24 via 192.168.1.1I'm assuming that 192.168.1.1 as the ip to traffic manually routes to those networks here. Isn't something 192.168.100.0/24? To auto delete those routes when disconnecting a pptp tunnel, just create a /etc/ppp/ip-down.local file with the following contents:#!/bin/bash/sbin/ip route del 192.168.10.0/24 /sbin/ip route del 192.168.20.0/24