Почему не пингуется VPN L2TP клиент с VPN L2TP сервера?

# iptables -L -v -n
# iptables -t nat -L -v -n
# iptables -t mangle -L -v -n

Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination
Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination