I configured vpn with openswan. To allow L2TP vpn connections new interface got created: ppp0. Here's what ifconfig shows:
ppp0: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST> mtu 1410 inet MY_VPN_GATEWAY netmask 255.255.255.255 destination MY_VPN_DEST ppp txqueuelen 3 (Point-to-Point Protocol) RX packets 13 bytes 1528 (1.4 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 14 bytes 1236 (1.2 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
Why new interface is needed to support vpn connections?
Can't I just add routes to required hosts using default interface eth0?
What's the difference between having default interface eth0 and ppp0? (ip route add default via SOME_IP)