Port tracking on dynamically negotiated ports
View Patent ↗Techniques for tracking dynamically negotiated port connections in a network include collecting statistical information on packets that are sent between nodes on a network, inspecting packets of control connections to detect payload fragments that denote ephemeral port negotiation and producing a mapping from a ephemeral connection flow_id to a control connection flow_id. The techniques also include checking the flow_id to see whether a flow record maps to a control connection.
1. A system, comprising:
a plurality of collector devices that are disposed to collect information based on packets sent between nodes in a network, the collector devices including circuitry to:
inspect packets of control connections to detect payload fragments that denote an ephemeral port negotiation; and
produce a mapping from an ephemeral connection flow identifier to a control connection flow identifier,
wherein the ephemeral connection flow identifier includes a destination address, an unknown port, a client destination address, and a client destination port, and
wherein the control connection flow identifier includes a source address, source port, a destination address, and a destination port;
an aggregator that receives the mapping data from the plurality of collector devices; and
check a flow identifier associated with a flow record received by the aggregator to see whether the flow record maps to a control connection.
2. The system of claim 1 wherein if the flow identifier maps to a control connection, then the aggregator indicates that the flow record corresponds to an ephemeral flow for a known control connection.
3. The system of claim 2 wherein the aggregator associates ephemeral flow statistics with those of the well-known protocol that corresponds to the control connection.
4. The system of claim 1 wherein the aggregator expires the ephemeral flow identifier mappings after a configurable timeout.
5. The system of claim 1 wherein the aggregator performs an application-specific analysis without the need to transfer actual packet payloads from the collector to the aggregator.
6. The system of claim 1 wherein the collectors examine all packets on a specific port for a specific connection protocol.
7. The system of claim 6 wherein the protocol being tracked is the ftp and the connection port examined is port 21/tcp.
8. The system of claim 1 wherein payload fragments that denote ephemeral port negotiation for FTP are ‘PORT’ and ‘227’ FTP commands.
9. The system of claim 1 wherein the collector sends the new mapping in a message to the aggregator.
10. A collector device disposed to collect statistical information on packets sent between nodes on a network, the collector device, comprising:
a processor;
a memory executing instructions to cause the collector device to:
inspect packets of control connections to detect payload fragments that denote ephemeral port negotiation;
produce a mapping from an ephemeral connection flow identifier to a control connection flow identifier,
wherein the ephemeral connection flow identifier includes a destination address, an unknown port, a client destination address, and a client destination port, and
wherein the control connection flow identifier includes a source address, source port, a destination address, and a destination port; and send the mapping to a device.
11. The device of claim 10 wherein the collector examines all packets on a specific port for a specific connection protocol.
12. The device of claim 11 wherein the protocol tracked is the ftp and the connection port examined is port 21/tcp.
13. The device of claim 12 wherein payload fragments that denote ephemeral port negotiation for FTP are ‘PORT’ and ‘227’ FTP commands.
14. The device of claim 10 wherein the collector sends the new mapping in a message to the aggregator.
15. A device, comprising:
a processor;
a memory executing instructions to cause the device to:
receive mappings of a ephemeral connection flow identifier to control connection flow identifier from a plurality of collector devices,
wherein the ephemeral connection flow identifier includes a destination address, an unknown port, a client destination address, and a client destination port, and
wherein the control connection flow identifier includes a source address, source port, a destination address, and a destination port; and
check the flow identifier to see whether a received flow record maps to a control connection.
16. The device of claim 15 wherein the instructions to check further comprise instructions to determine if the flow identifier maps to a control connection, and if the flow identifier maps to a flow connection,
produce an indication that the flow record corresponds to an ephemeral flow for a known control connection.
17. The device of claim 16 wherein the device associates ephemeral flow statistics with those of the well-known protocol that corresponds to the control connection.
18. The device of claim 15 further comprising instructions to:
expire the ephemeral flow identifier mappings after a configurable timeout period.
19. A computer program product residing on a computer readable medium for tracking dynamically negotiated port numbers comprises instructions for causing a computer to:
collect statistical information on packets that are sent between nodes on a network;
inspect packets of control connections to detect payload fragments that denote ephemeral port negotiation;
produce a mapping from a ephemeral connection flow identifier to a control connection flow identifier,
wherein the ephemeral connection flow identifier includes a destination address, an unknown port, a client destination address, and a client destination port, and
wherein the control connection flow identifier includes a source address, source port, a destination address, and a destination port; and
check the flow identifier to see whether a flow record maps to a control connection.
20. The computer program product of claim 19 further comprising instructions to indicate that the flow record corresponds to an ephemeral flow for a known control connection.
21. The computer program product of claim 19 further comprising instructions to associate ephemeral flow statistics with those of a well-known protocol that corresponds to the control connection.
22. The computer program product of claim 19 further comprising instructions to expire the ephemeral flow identifier mappings after a configurable timeout.
23. The computer program product of claim 19 further comprising instructions to examine all packets on a specific port for a specific connection protocol.
24. A computer program product residing on a computer readable medium for determining mappings for ephemeral port connections comprising instructions to cause a computing device to:
inspect packets of control connections to detect payload fragments that denote ephemeral port negotiation;
produce a mapping from a ephemeral connection flow identifier to a control connection flow id,
wherein the ephemeral connection flow identifier includes a destination address, an unknown port, a client destination address, and a client destination port, and
wherein the control connection flow identifier includes a source address, source port, a destination address, and a destination port; and
send the mapping to a device to associate the mapping with ephemeral connections.
25. The computer program product of claim 24 further comprising instructions to examines all packets on a specific port for a specific connection protocol.
26. The computer program product of claim 24 wherein the protocol tracked is the ftp and the connection port examined is port 21/tcp.
27. The computer program product of claim 24 wherein payload fragments that denote ephemeral port negotiation for FTP are ‘PORT’ and ‘227’ FTP commands.
28. A computer program product residing on a computer readable medium for determining ephemeral port connections comprising instructions to cause a computing device to:
receive, from a plurality of collector devices, mappings corresponding to a ephemeral connection flow identifier to a control connection flow identifier,
wherein the ephemeral connection flow identifier includes a destination address, an unknown port, a client destination address, and a client destination port, and
wherein the control connection flow identifier includes a source address, source port, a destination address, and a destination port; and
check the flow identifier to see whether a received flow record maps to a control connection.
29. The computer program of claim 28 wherein the instructions to check further comprise instructions to determine if the flow identifier maps to a control connection; and if the flow identifier maps to a control connection,
produce an indication that the flow record corresponds to an ephemeral flow for a known control connection.
30. The computer program product of claim 28 wherein the device associates ephemeral flow statistics with those of a well-known protocol that corresponds to the control connection.
31. A computer implemented method for tracking dynamically negotiated port connections, the method comprising:
collecting statistical information on packets that are sent between nodes on a network;
inspecting packets of control connections to detect payload fragments that denote ephemeral port negotiation;
producing a mapping from a ephemeral connection flow identifier to a control connection flow identifier,
wherein the ephemeral connection flow identifier includes a destination address, an unknown port, a client destination address, and a client destination port, and
wherein the control connection flow identifier includes a source address, source port, a destination address, and a destination port; and
checking the flow identifier to see whether a flow record maps to a control connection.
32. The method of claim 31 further comprising associating ephemeral flow statistics with those of a well-known protocol that corresponds to the control connection.