How get vpn0 IP address

I have an LEDE 17.01.4 router with openvpn running as client of an other LEDE 17.01.4 with openvpn server.
Both connect to each other. On server I discover the clients IP addres and can ping it.
At the client, thus I know his vpn0 address I found on server, I can ping it.
But, if I have no access to the server, how can I find out the vpn0 IP address on client?

ubus call network.interface dump

The only IP address that not is shown is from vpn0. Why and where can I find it?
Best vregards,

With "ip addr show dev tun0" (or whatever is called your VPN interface) you should obtain the information for the VPN interface.

Thanks eduperez. It works.
But there must be a problem with ubus that is "almost" complete.

openvpn isn't really integrated into netifd which is the issue. Perhaps someday someone will write protocol script for openvpn.

Thanks for this comment. Now I know why.