I have installed Softher vpnserver version 4.20 on a Ubuntu 16.04.2 server. The IPSec protocal is enabled in the server. Our clients are using mobile devices for connecting to the vpn. After establishing connection we are getting public IP address of client server in log file. We need to get private IP address of client device in the logs. Is there any method available to get private ip address in VPN server logs?

have you used softether. I am trying to create a vpn sever for people to use. need outline on setting i up correctly

I think private address may log.
Could you show the log?

I did it next way:
Create a new tap device
Add it to bridge (make sure, that bridge-utils are installed)
Assign a static address for bridge interface in /etc/network/interfaces
e.g.
##########
iface br0 inet static
address 10.10.10.1
netmask 255.255.255.0
broadcast 10.10.10.255
bridge_ports tap_vpn
bridge_fd 0
bridge_stp 1
##########
then instal any dhcp server. i used dnsmasq
configure your dhcp server to listen br0 interface and configure an address pool

Than your vpn clients will get an IP address with your dhcp server. And you can add routes with 'ip route" utils, and forward or masquarade your traffic with iptables.

Sorry for my poor english.