Dynamic firewall discovery on a service plane in a SDWAN architecture

1. A system, comprising:

one or more processors; and

one or more computer-readable non-transitory storage media comprising instructions that, when executed by the one or more processors, cause one or more components of the system to perform operations comprising:

identifying a source data packet for transmission from a source machine at a source site to a destination machine at a destination site, wherein the source data packet corresponds to a request for connection between the source machine and the destination machine over a wide area network (WAN);

inspecting the source data packet at a first firewall associated with the source site;

marking the source data packet with a marker to indicate inspection by the first firewall;

transmitting the marked source data packet to the destination site;

determining, at the destination site, that the source data packet has been inspected based on the marker; and

forwarding the source data packet to the destination machine at the destination site, without inspection of the source data packet by a second firewall associated with the destination site.

2. The system of claim 1 , wherein the operations further comprise:

identifying an acknowledgment data packet for reverse transmission from the destination machine at the destination site to the source machine at the source site, wherein the acknowledgment data packet is to be reverse transmitted in response to the source data packet;

transmitting the acknowledgement data packet from the destination site to the source site without inspection of the acknowledgment data packet by the second firewall associated with the destination site;

determining, at the source site, that the acknowledgment data packet is associated with the source data packet;

inspecting the acknowledgment data packet at the first firewall associated with the source site; and

forwarding the acknowledgment data packet to the source machine at the source site.

3. The system of claim 2 , wherein the source data packet is a SYN packet, and the acknowledgement data packet is a SYN/ACK packet.

4. The system of claim 2 , wherein the marking step further comprises:

creating a flow table entry associated with the source data packet.

5. The system of claim 4 , wherein the acknowledgment data packet is determined to be associated with the source data packet based on the flow table entry.

6. The system of claim 1 , wherein the marker is based on a field of a Transmission Control Protocol (TCP) header of the source data packet.

7. The system of claim 6 , wherein the marker comprises:

a redirect flag.

8. A method, comprising:

identifying a source data packet for transmission from a source machine at a source site to a destination machine at a destination site, wherein the source data packet corresponds to a request for connection between the source machine and the destination machine over a wide area network (WAN);

inspecting the source data packet at a first firewall associated with the source site;

marking the source data packet with a marker to indicate inspection by the first firewall;

transmitting the marked source data packet to the destination site;

determining, at the destination site, that the source data packet has been inspected based on the marker; and

forwarding the source data packet to the destination machine at the destination site, without inspection of the source data packet by a second firewall associated with the destination site.

9. The method of claim 8 , further comprising:

identifying an acknowledgment data packet for reverse transmission from the destination machine at the destination site to the source machine at the source site, wherein the acknowledgment data packet is to be reverse transmitted in response to the source data packet;

transmitting the acknowledgement data packet from the destination site to the source site without inspection of the acknowledgment data packet by the second firewall associated with the destination site;

determining, at the source site, that the acknowledgment data packet is associated with the source data packet;

inspecting the acknowledgment data packet at the first firewall associated with the source site; and

forwarding the acknowledgment data packet to the source machine at the source site.

10. The method of claim 9 , wherein the source data packet is a SYN packet, and the acknowledgement data packet is a SYN/ACK packet.

11. The method of claim 9 , wherein the marking step further comprises:

creating a flow table entry associated with the source data packet.

12. The method of claim 11 , wherein the acknowledgment data packet is determined to be associated with the source data packet based on the flow table entry.

13. The method of claim 8 , wherein the marker is based on a field in a Transmission Control Protocol (TCP) header of the source data packet.

14. The method of claim 13 , wherein the marker comprises:

a redirect flag.

15. One or more computer-readable non-transitory storage media embodying instructions that, when executed by a processor, cause the performance of operations comprising:

identifying a source data packet for transmission from a source machine at a source site to a destination machine at a destination site, wherein the source data packet corresponds to a request for connection between the source machine and the destination machine over a wide area network (WAN);

inspecting the source data packet at a first firewall associated with the source site;

marking the source data packet with a marker to indicate inspection by the first firewall;

transmitting the marked source data packet to the destination site;

determining, at the destination site, that the source data packet has been inspected based on the marker; and

forwarding the source data packet to the destination machine at the destination site, without inspection of the source data packet by a second firewall associated with the destination site.

16. The one or more computer-readable non-transitory storage media of claim 15 , wherein the operations further comprise:

identifying an acknowledgment data packet for reverse transmission from the destination machine at the destination site to the source machine at the source site, wherein the acknowledgment data packet is to be reverse transmitted in response to the source data packet;

transmitting the acknowledgement data packet from the destination site to the source site without inspection of the acknowledgment data packet by the second firewall associated with the destination site;

determining, at the source site, that the acknowledgment data packet is associated with the source data packet;

inspecting the acknowledgment data packet at the first firewall associated with the source site; and

forwarding the acknowledgment data packet to the source machine at the source site.

17. The one or more computer-readable non-transitory storage media of claim 16 , wherein the source data packet is a SYN packet, and the acknowledgement data packet is a SYN/ACK packet.

18. The one or more computer-readable non-transitory storage media of claim 16 , wherein the marking step further comprises:

creating a flow table entry associated with the source data packet.

19. The one or more computer-readable non-transitory storage media of claim 18 , wherein the acknowledgment data packet is determined to be associated with the source data packet based on the flow table entry.

20. The one or more computer-readable non-transitory storage media of claim 15 , wherein the marker is based on a field of a Transmission Control Protocol (TCP) header of the source data packet.