Networking :: VPN in DSL

Has anybody tried using this howto: http://tldp.org/HOWTO/ppp-ssh/index.html to build VPNs in DSL?

I am now following this howto to build VPNs. I can start VPN successfully as I saw interfaces PPP0 were setup on both computers by issuing ifconfig and route -n. However, I could not ping the host after the VPN had been up. Could somebody tell me why?

Since DSL is a cdrom distro, any tricky to setup VPN?

After I've reviewed the steps again, I know what was missing. Since I'm trying to connect networks under VPNs, IP forwarding must be enable. The tutuial wrote this:

echo 1 > /proc/sys/net/ipv4/ip_forward. But the file ip_foword had not been updated after I issued this command. I think this is because file systems are read only.

But how can I enable IP forwarding in DSL without re-compiling kernel (what a difficult task)?

original here.