One rule for multiple interfaces

[nimamhd]

I install oserv VPN server and working fine,but the problem is,oserve  assign unique interface to new VPN client(user1:tun0 ,user2:tun1,…). These interfaces is not available until user connect.
How can I add a firewall rule to all tun interfaces for client,instead to add one by one, like openvpn?

I'm also unhide "tun" interface.