How to set a route to a GRE tunnel host through a VPN?

Question

linux

Guys, such a question raised a GRE tunnel to another remote host.
Configuration example

spoiler

auto gre1
iface gre1 inet static
address 172.17.121.230
netmask 255.255.255.0
up ifconfig gre1 multicast
pre-up iptunnel add gre1 mode gre local xxx.xxx.xxx.xxx remote xxx.xxx.xxx.xxx dev ens3
post-up route add -net 172.17.121.0 netmask 255.255.255.0 gw 172.17.121.229
pointopoint 172.17.121.229
post-down iptunnel del gre1

on the server itself, the ping goes to 172.17.121.229. But it is necessary that the hosts connected to the server via VPN
ping to 172.17.121.229 - also went. Is it realistic to do it?