Now we move onto the client. First we must rebuild the kernel so that it can support all of the functions that we need. The minimum requirement is to have ppp in the kernel. You will need forwarding, a firewall, and a gateway only if you are going to allow other machines access to the tunnel. For this example, I will setup one of the remote office machines in my example layout. Add the following options to your kernel. Again, if you've never built a kernel before, read the Kernel HOWTO.
For 2.0 kernels:
CONFIG_PPP
CONFIG_FIREWALL
CONFIG_IP_FORWARD
CONFIG_IP_FIREWALL
CONFIG_IP_ROUTER
CONFIG_IP_MASQUERADE
CONFIG_IP_MASQUERADE_ICMP
For 2.2 kernels:
CONFIG_PPP
CONFIG_FIREWALL
CONFIG_IP_ADVANCED_ROUTER
CONFIG_IP_FIREWALL
CONFIG_IP_ROUTER
CONFIG_IP_MASQUERADE
CONFIG_IP_MASQUERADE_ICMP