I've successfully set up a VPN server with openswan, pppd, and xl2tpd on Ubuntu.
Everything works great, but I'm having trouble finding out how to only allow one VPN connection per user listed in the /etc/ppp/chap-secrets file?
Right now a user can have unlimited connections which is worrisome to me as I've shared access to the VPN with some friends but am worried they might keep spreading the username/password.
I think you need uniqueids=yes in ipsec.conf