Object FlowID

In Trisul, flows are identified by a strings that look like this 06A:C0.A8.01.02:p-0B94_D1.D8.F9.3A:p-0016

The string encodes the tuples that make up the flow. The FlowID object described in this page makes working with these types of strings easier.

Structure of flow key in Trisul

Trisul support 3 types of flows 1) plain IPv4 2) IPv4 with Netflow and 3) Plain IPv6. The following image shows the structure of these 3 flow IDs. Luckily you never have to construct these keys yourselfs. LUA calls into your functions that involve a network flow will use an object called FlowID that wraps this for you. See How to get or create a flowID

Methods

_Readable methods
The readable versions return friendly strings whereas the plain methods return TrisulKey format strings.
For example : ipa might return FF020000000000000000000000000002 where ipa_readable returns ff02::2. The raw method is faster than the “readable” method, but the readable method is easier to work with. That is why we have provided both using the API.
Name In Out Description
id string A unique string identifying the flow, see the section above
key string Synonym for id() method above
protocol string IP protocol in hex, TCP/GRE/UDP/etc – so UDP which is protocol 17 as per IANA will be represented as 11
ipa string Trisul Key Format : IP Address of A-End can be IPv4 or IPv6
ipa_readable string Human readable format : IP Address of A-End can be IPv4 or IPv6
porta string Trisul Key Format : port
porta_readable string Human readable format : port number for TCP/UDP flows. For IP flows this can contain a protocol string like “ipsec0”, so make sure you check for this.
ipz string Trisul Key Format : IP Address of A-End can be IPv4 or IPv6
ipz_readable string Human readable format : IP Address of A-End can be IPv4 or IPv6
portz string Trisul Key Format : port
portz_readable string Human readable format : port number. See porta_readable remarks
netflow_router string Netflow router ID. This is in key format. such as 0A.81.4A.92. For a printable format use netflow_router_readable
netflow_ifindex_in string Netflow input ifIndex. This is an 8 digit HEX interface index such as 0000000A. Use the _readable method to intepret it as ifIndex 10
netflow_ifindex_out string Netflow output ifIndex
to_s string convenience method returns a string. The fields are correctly padded to aid in table format printing. The order of the fields are Protocol, A-End IP, A-End Port, Z-End IP, Z-End Port, then if Netflow details are available Netflow Router IP, IfIndex_In, IfIndex_Out

p flow:to_s()
flow:to_s() “TCP 10.4.13.111 49231 192.168.2.8 80”
p flow:flow():to_s()
flow:flow():to_s() => "TCP 10.131.17.9 61868 116.90.243.38 52311 10.129.74.146 10 11 "
flow_type string Type of flow. A single character

  • ‘A’ : IPv4 Flow

  • ‘B’ : IPv6 Flow

  • ‘C’ : IPv4 Flow with Netflow details

netflow_router_readable string Netflow Exporting Router IP Address
netflow_ifindex_in_readable string Netflow Interface Index IN.
netflow_ifindex_out_readable string Netflow Interface Index OUT.

How to get or create a flow ID

You can create the flowID string manually using the above formula. In Trisul LUA Scripting you rarely would need to create the flow ID because it is passed to you in many cases by the framework. For example : The onnewresource method in the Resource Monitor scripts pass you a flow object.

So you simply use that as shown here



onflush=function(engine,resource)

     engine:add_resource('{EE1C9F46-0542-4A7E-4C6A-55E2C4689419}',
               resource:flow():id(),    ----> the flow ID is passed to you
               "INDICATOR:DNSIP6",
               ip);



Alternately in some script types like simplecounter you do not have access to a flowID, you can construct one using the Packet:flowid method.



onpacket=function(engine,layerdata)

     engine:add_resource('{EE1C9F46-0542-4A7E-4C6A-55E2C4689419}',
               layerdata:packet():flowid(),    ----> create the flowID from the packet object 
               "INDICATOR:DNSIP6",
               ip);