SonicWall security appliance can be used to establish a L2TP VPN connection. Once the Client is connected, a scrolling window shows the details of the current bindings: Username, IP Address of the Client, Zone through which the connection is established, Interface Name, Authentication method used and Host Name.
Login to the SonicWall Management Interface. Navigate to VPN >L2TP Server.
The scrolling window shows the details of the Current DHCP leases, which includes the username, IP Address of the client, zone and interface name, authentication method and the host name.
To delete a binding which frees the IP address in the DHCP Server, select the binding from the list and click the button. This operation takes a few seconds to complete, once completed, a message confirming the update is seen at the bottom of the Web browser window.