Microsoft uses DHCP Info for getting additional parametres to client after established VPN (PPTP and others). Is it possible to add support (answering) for this requests?
Example of DHCP Info packet from Windows client:
Frame 1: 342 bytes on wire (2736 bits), 342 bytes captured (2736 bits)
Ethernet II, Src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00)
Internet Protocol Version 4, Src: 10.0.0.3, Dst: 255.255.255.255
User Datagram Protocol, Src Port: 68 (68), Dst Port: 67 (67)
Bootstrap Protocol (Inform)
Message type: Boot Request (1)
Hardware type: Hyperchannel (0x08)
Hardware address length: 0
Hops: 0
Transaction ID: 0xea3be860
Seconds elapsed: 6
Bootp flags: 0x0000 (Unicast)
Client IP address: 10.0.0.3
Your (client) IP address: 0.0.0.0
Next server IP address: 0.0.0.0
Relay agent IP address: 0.0.0.0
Client address not given
Server host name not given
Boot file name not given
Magic cookie: DHCP
Option: (53) DHCP Message Type (Inform)
Option: (61) Client identifier
Option: (12) Host Name
Option: (60) Vendor class identifier
Option: (55) Parameter Request List
Length: 6
Parameter Request List Item: (6) Domain Name Server
Parameter Request List Item: (44) NetBIOS over TCP/IP Name Server
Parameter Request List Item: (43) Vendor-Specific Information
Parameter Request List Item: (1) Subnet Mask
Parameter Request List Item: (249) Private/Classless Static Route (Microsoft)
Parameter Request List Item: (15) Domain Name
Option: (255) End
Padding: 0000000000000000000000000000
More info for example here: http://www.janoszen.com/2012/08/07/in-search-of-the-perfect-vpn-solution/
or: http://serverfault.com/questions/574121/is-it-possible-for-l2tp-vpn-to-do-auto-route-configuration-for-client-during-con