Identifying end-stations on private networks
A protocol such as OpenFlow providing communication between an SDN framework controller on one network and a data plane device for another network can be used to modify or process network packets so that an external application or server can communicate with the controller and obtain information needed to uniquely associate the packets with particular end-stations even after those packets have traversed a NAT router.
1. A process comprising:
receiving, at a controller on a first network, a message from a data-path device on a second network, wherein the message contains a packet that was encapsulated into the message, the packet being from an end-station on the second network and being encapsulated before the packet passes through a network address translation (NAT) device between the second network and the first network;
from the message at the controller, determining identifying information that identifies the end-station;
the controller modifying content of the packet to create a modified packet;
the controller mapping the identifying information to a packet characteristic, wherein the packet characteristic is a hash value calculated from contents of the modified packet;
conveying to a server seeking to distinguish end-stations that the packet characteristic maps to the end-station;
the controller sending to the data-path device, a second message in which the modified packet is encapsulated; and
the data-path device forwarding the modified packet.
2. The process of claim 1 , wherein the controller modifies the content of the packet so that the hash value of the modified packet uniquely identifies the modified packet as corresponding to the end station.
3. A process comprising:
receiving, at a controller on a first network, a message from a data-path device on a second network, wherein the message contains a packet that was encapsulated into the message, the packet being from an end-station on the second network and being encapsulated before the packet passes through a network address translation (NAT) device between the second network and the first network;
from the message at the controller, identifying the end-station;
the controller assigning to the end-station a destination IP address selected from among a plurality of IP addresses of a server outside of the second network, the destination IP address being at least temporarily associated uniquely with the end-station;
conveying to the server that the communication parameter is assigned to the end-station; and
programming the data-path device to modify packets from the end-station so that the packets, when directed through the NAT device, use the destination IP address assigned to the end-station, wherein
the server identifies packets as being from the end-station based on receiving the packets at the destination IP address associated with the end-station.
4. The process of claim 3 , wherein the second network is a private network.
5. The process of claim 3 , wherein the data-path device is an OpenFlow device, and the controller is an OpenFlow controller.
6. The process of claim 3 , wherein the server is on the second network.
7. A process comprising:
receiving, at a controller on a first network, a message from a data-path device on a second network, wherein the message contains a packet that was encapsulated into the message, the packet being from an end-station on the second network and being encapsulated before the packet passes through a network address translation (NAT) device between the second network and the first network;
from the message at the controller, identifying the end-station;
the controller assigning to the end-station a communication parameter selected from among a plurality of available communication parameters;
conveying to a server outside of the second network that the communication parameter is assigned to the end-station, wherein the server is a redirection server;
programming the data-path device to modify packets from the end-station so that the packets, when directed through the NAT device, use the communication parameter assigned to the end-station;
the server receiving a received packet via the NAT device; and
the server identifying the end-station as source of the received packet based on the communication parameter being used in the received packet.
8. The process of claim 7 , wherein the communication parameter is a destination IP address that is at least temporarily associated uniquely with the end-station.
9. The process of claim 7 , wherein the communication parameter is a source port number that is at least temporarily uniquely associated with the end-station.
10. The process of claim 7 , wherein the communication parameter is a value of an IP options field that is at least temporarily uniquely associated with the end-station.
11. The process of claim 7 , further comprising:
the server receiving a received packet via the NAT device; and
the server identifying the end-station as source of the received packet based on the communication parameter being used in the received packet.
12. The process of claim 7 , further comprising:
the controller receiving address information of a captive portal server; and
programming the data-path device to permit the end-station to communicate with the captive portal server.
13. The process of claim 7 , further comprising releasing assignment of the communication parameter to the end-station to thereby permit the communication parameter to be uniquely assigned to another end-station on the second network.