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Traffic analytics schema and data aggregation

  • บทความ

Traffic analytics is a cloud-based solution that provides visibility into user and application activity in cloud networks. Traffic analytics analyzes Azure Network Watcher flow logs to provide insights into traffic flow in your Azure cloud. With traffic analytics, you can:

  • Visualize network activity across your Azure subscriptions and identify hot spots.
  • Identify security threats, and secure your network, with information such as open-ports, applications attempting internet access, and virtual machines (VMs) connecting to rogue networks.
  • Understand traffic flow patterns across Azure regions and the internet to optimize your network deployment for performance and capacity.
  • Pinpoint network misconfigurations leading to failed connections in your network.
  • Know network usage in bytes, packets, or flows.

Data aggregation

  • All flow logs at a network security group between FlowIntervalStartTime_t and FlowIntervalEndTime_t are captured at one-minute intervals as blobs in a storage account.
  • Default processing interval of traffic analytics is 60 minutes, meaning that every hour, traffic analytics picks blobs from the storage account for aggregation. However, if a processing interval of 10 minutes is selected, traffic analytics will instead pick blobs from the storage account every 10 minutes.
  • Flows that have the same Source IP, Destination IP, Destination port, NSG name, NSG rule, Flow Direction, and Transport layer protocol (TCP or UDP) are clubbed into a single flow by traffic analytics (Note: source port is excluded for aggregation).
  • This single record is decorated (details in the section below) and ingested in Azure Monitor logs by traffic analytics. This process can take up to 1 hour.
  • FlowStartTime_t field indicates the first occurrence of such an aggregated flow (same four-tuple) in the flow log processing interval between FlowIntervalStartTime_t and FlowIntervalEndTime_t.
  • For any resource in traffic analytics, the flows indicated in the Azure portal are total flows seen by the network security group, but in Azure Monitor logs, user sees only the single, reduced record. To see all the flows, use the blob_id field, which can be referenced from storage. The total flow count for that record matches the individual flows seen in the blob.

The following query helps you look at all subnets interacting with non-Azure public IPs in the last 30 days.

AzureNetworkAnalytics_CL
| where SubType_s == "FlowLog" and FlowStartTime_t >= ago(30d) and FlowType_s == "ExternalPublic"
| project Subnet1_s, Subnet2_s

To view the blob path for the flows in the previous query, use the following query:

let TableWithBlobId =
(AzureNetworkAnalytics_CL
   | where SubType_s == "Topology" and ResourceType == "NetworkSecurityGroup" and DiscoveryRegion_s == Region_s and IsFlowEnabled_b
   | extend binTime = bin(TimeProcessed_t, 6h),
            nsgId = strcat(Subscription_g, "/", Name_s),
            saNameSplit = split(FlowLogStorageAccount_s, "/")
   | extend saName = iif(arraylength(saNameSplit) == 3, saNameSplit[2], '')
   | distinct nsgId, saName, binTime)
| join kind = rightouter (
   AzureNetworkAnalytics_CL
   | where SubType_s == "FlowLog"  
   | extend binTime = bin(FlowEndTime_t, 6h)
) on binTime, $left.nsgId == $right.NSGList_s  
| extend blobTime = format_datetime(todatetime(FlowIntervalStartTime_t), "yyyy MM dd hh")
| extend nsgComponents = split(toupper(NSGList_s), "/"), dateTimeComponents = split(blobTime, " ")
| extend BlobPath = strcat("https://", saName,
                        "@insights-logs-networksecuritygroupflowevent/resoureId=/SUBSCRIPTIONS/", nsgComponents[0],
                        "/RESOURCEGROUPS/", nsgComponents[1],
                        "/PROVIDERS/MICROSOFT.NETWORK/NETWORKSECURITYGROUPS/", nsgComponents[2],
                        "/y=", dateTimeComponents[0], "/m=", dateTimeComponents[1], "/d=", dateTimeComponents[2], "/h=", dateTimeComponents[3],
                        "/m=00/macAddress=", replace(@"-", "", MACAddress_s),
                        "/PT1H.json")
| project-away nsgId, saName, binTime, blobTime, nsgComponents, dateTimeComponents;

TableWithBlobId
| where SubType_s == "FlowLog" and FlowStartTime_t >= ago(30d) and FlowType_s == "ExternalPublic"
| project Subnet_s , BlobPath

The previous query constructs a URL to access the blob directly. The URL with placeholders is as follows:

https://{storageAccountName}@insights-logs-networksecuritygroupflowevent/resoureId=/SUBSCRIPTIONS/{subscriptionId}/RESOURCEGROUPS/{resourceGroup}/PROVIDERS/MICROSOFT.NETWORK/NETWORKSECURITYGROUPS/{networkSecurityGroupName}/y={year}/m={month}/d={day}/h={hour}/m=00/macAddress={macAddress}/PT1H.json

Traffic analytics schema

Traffic analytics is built on top of Azure Monitor logs, so you can run custom queries on data decorated by traffic analytics and set alerts.

The following table lists the fields in the schema and what they signify for network security group flow logs.

Field Format Comments
TableName AzureNetworkAnalytics_CL Table for traffic analytics data.
SubType_s FlowLog Subtype for the flow logs. Use only FlowLog, other values of SubType_s are for internal use.
FASchemaVersion_s 2 Schema version. Doesn't reflect network security group flow log version.
TimeProcessed_t Date and time in UTC Time at which the traffic analytics processed the raw flow logs from the storage account.
FlowIntervalStartTime_t Date and time in UTC Starting time of the flow log processing interval (time from which flow interval is measured).
FlowIntervalEndTime_t Date and time in UTC Ending time of the flow log processing interval.
FlowStartTime_t Date and time in UTC First occurrence of the flow (which gets aggregated) in the flow log processing interval between FlowIntervalStartTime_t and FlowIntervalEndTime_t. This flow gets aggregated based on aggregation logic.
FlowEndTime_t Date and time in UTC Last occurrence of the flow (which gets aggregated) in the flow log processing interval between FlowIntervalStartTime_t and FlowIntervalEndTime_t. In terms of flow log v2, this field contains the time when the last flow with the same four-tuple started (marked as B in the raw flow record).
FlowType_s - IntraVNet
- InterVNet
- S2S
- P2S
- AzurePublic
- ExternalPublic
- MaliciousFlow
- Unknown Private
- Unknown		 See Notes for definitions.
SrcIP_s Source IP address Blank in AzurePublic and ExternalPublic flows.
DestIP_s Destination IP address Blank in AzurePublic and ExternalPublic flows.
VMIP_s IP of the VM Used for AzurePublic and ExternalPublic flows.
DestPort_d Destination Port Port at which traffic is incoming.
L4Protocol_s - T
- U		 Transport Protocol. T = TCP
U = UDP.
L7Protocol_s Protocol Name Derived from destination port.
FlowDirection_s - I = Inbound
- O = Outbound		 Direction of the flow: in or out of network security group per flow log.
FlowStatus_s - A = Allowed
- D = Denied		 Status of flow whether allowed or denied by the network security group per flow log.
NSGList_s <SUBSCRIPTIONID>/<RESOURCEGROUP_NAME>/<NSG_NAME> Network security group associated with the flow.
NSGRules_s <Index value 0>|<NSG_RULENAME>|<Flow Direction>|<Flow Status>|<FlowCount ProcessedByRule> Network security group rule that allowed or denied this flow.
NSGRule_s NSG_RULENAME Network security group rule that allowed or denied this flow.
NSGRuleType_s - User Defined
- Default		 The type of network security group rule used by the flow.
MACAddress_s MAC Address MAC address of the NIC at which the flow was captured.
Subscription_g Subscription of the Azure virtual network / network interface / virtual machine is populated in this field Applicable only for FlowType = S2S, P2S, AzurePublic, ExternalPublic, MaliciousFlow, and UnknownPrivate flow types (flow types where only one side is Azure).
Subscription1_g Subscription ID Subscription ID of virtual network / network interface / virtual machine that the source IP in the flow belongs to.
Subscription2_g Subscription ID Subscription ID of virtual network/ network interface / virtual machine that the destination IP in the flow belongs to.
Region_s Azure region of virtual network / network interface / virtual machine that the IP in the flow belongs to. Applicable only for FlowType = S2S, P2S, AzurePublic, ExternalPublic, MaliciousFlow, and UnknownPrivate flow types (flow types where only one side is Azure).
Region1_s Azure Region Azure region of virtual network / network interface / virtual machine that the source IP in the flow belongs to.
Region2_s Azure Region Azure region of virtual network that the destination IP in the flow belongs to.
NIC_s <resourcegroup_Name>/<NetworkInterfaceName> NIC associated with the VM sending or receiving the traffic.
NIC1_s <resourcegroup_Name>/<NetworkInterfaceName> NIC associated with the source IP in the flow.
NIC2_s <resourcegroup_Name>/<NetworkInterfaceName> NIC associated with the destination IP in the flow.
VM_s <resourcegroup_Name>/<NetworkInterfaceName> Virtual Machine associated with the Network interface NIC_s.
VM1_s <resourcegroup_Name>/<VirtualMachineName> Virtual Machine associated with the source IP in the flow.
VM2_s <resourcegroup_Name>/<VirtualMachineName> Virtual Machine associated with the destination IP in the flow.
Subnet_s <ResourceGroup_Name>/<VirtualNetwork_Name>/<SubnetName> Subnet associated with the NIC_s.
Subnet1_s <ResourceGroup_Name>/<VirtualNetwork_Name>/<SubnetName> Subnet associated with the Source IP in the flow.
Subnet2_s <ResourceGroup_Name>/<VirtualNetwork_Name>/<SubnetName> Subnet associated with the Destination IP in the flow.
ApplicationGateway1_s <SubscriptionID>/<ResourceGroupName>/<ApplicationGatewayName> Application gateway associated with the Source IP in the flow.
ApplicationGateway2_s <SubscriptionID>/<ResourceGroupName>/<ApplicationGatewayName> Application gateway associated with the Destination IP in the flow.
ExpressRouteCircuit1_s <SubscriptionID>/<ResourceGroupName>/<ExpressRouteCircuitName> ExpressRoute circuit ID - when flow is sent from site via ExpressRoute.
ExpressRouteCircuit2_s <SubscriptionID>/<ResourceGroupName>/<ExpressRouteCircuitName> ExpressRoute circuit ID - when flow is received from cloud by ExpressRoute.
ExpressRouteCircuitPeeringType_s - AzurePrivatePeering
- AzurePublicPeering
- MicrosoftPeering		 ExpressRoute peering type involved in the flow.
LoadBalancer1_s <SubscriptionID>/<ResourceGroupName>/<LoadBalancerName> Load balancer associated with the Source IP in the flow.
LoadBalancer2_s <SubscriptionID>/<ResourceGroupName>/<LoadBalancerName> Load balancer associated with the Destination IP in the flow.
LocalNetworkGateway1_s <SubscriptionID>/<ResourceGroupName>/<LocalNetworkGatewayName> Local network gateway associated with the Source IP in the flow.
LocalNetworkGateway2_s <SubscriptionID>/<ResourceGroupName>/<LocalNetworkGatewayName> Local network gateway associated with the Destination IP in the flow.
ConnectionType_s - VNetPeering
- VpnGateway
- ExpressRoute		 The onnection Type.
ConnectionName_s <SubscriptionID>/<ResourceGroupName>/<ConnectionName> The connection Name. For flow type P2S, it is formatted as <gateway name>_<VPN Client IP>.
ConnectingVNets_s Space separated list of virtual network names In case of hub and spoke topology, hub virtual networks are populated here.
Country_s Two letter country code (ISO 3166-1 alpha-2) Populated for flow type ExternalPublic. All IP addresses in PublicIPs_s field share the same country code.
AzureRegion_s Azure region locations Populated for flow type AzurePublic. All IP addresses in PublicIPs_s field share the Azure region.
AllowedInFlows_d Count of inbound flows that were allowed, which represents the number of flows that shared the same four-tuple inbound to the network interface at which the flow was captured.
DeniedInFlows_d Count of inbound flows that were denied. (Inbound to the network interface at which the flow was captured).
AllowedOutFlows_d Count of outbound flows that were allowed (Outbound to the network interface at which the flow was captured).
DeniedOutFlows_d Count of outbound flows that were denied (Outbound to the network interface at which the flow was captured).
FlowCount_d Deprecated. Total flows that matched the same four-tuple. In case of flow types ExternalPublic and AzurePublic, count includes the flows from various PublicIP addresses as well.
InboundPackets_d Represents packets sent from the destination to the source of the flow Populated only for Version 2 of network security group flow log schema.
OutboundPackets_d Represents packets sent from the source to the destination of the flow Populated only for Version 2 of network security group flow log schema.
InboundBytes_d Represents bytes sent from the destination to the source of the flow Populated only for Version 2 of network security group flow log schema.
OutboundBytes_d Represents bytes sent from the source to the destination of the flow Populated only for Version 2 of network security group flow log schema.
CompletedFlows_d Populated with nonzero value only for Version 2 of network security group flow log schema.
PublicIPs_s <PUBLIC_IP>|<FLOW_STARTED_COUNT>|<FLOW_ENDED_COUNT>|<OUTBOUND_PACKETS>|<INBOUND_PACKETS>|<OUTBOUND_BYTES>|<INBOUND_BYTES> Entries separated by bars.
SrcPublicIPs_s <SOURCE_PUBLIC_IP>|<FLOW_STARTED_COUNT>|<FLOW_ENDED_COUNT>|<OUTBOUND_PACKETS>|<INBOUND_PACKETS>|<OUTBOUND_BYTES>|<INBOUND_BYTES> Entries separated by bars.
DestPublicIPs_s <DESTINATION_PUBLIC_IP>|<FLOW_STARTED_COUNT>|<FLOW_ENDED_COUNT>|<OUTBOUND_PACKETS>|<INBOUND_PACKETS>|<OUTBOUND_BYTES>|<INBOUND_BYTES> Entries separated by bars.
IsFlowCapturedAtUDRHop_b - True
- False		 If the flow was captured at a UDR hop, the value is True.

Important

The traffic analytics schema was updated on August 22, 2019. The new schema provides source and destination IPs separately, removing the need to parse the FlowDirection field so that queries are simpler. The updated schema had the following changes:

  • FASchemaVersion_s updated from 1 to 2.
  • Deprecated fields: VMIP_s, Subscription_g, Region_s, NSGRules_s, Subnet_s, VM_s, NIC_s, PublicIPs_s, FlowCount_d
  • New fields: SrcPublicIPs_s, DestPublicIPs_s, NSGRule_s

Public IP details schema

Traffic analytics provides WHOIS data and geographic location for all public IPs in your environment. For a malicious IP, traffic analytics provides DNS domain, threat type and thread descriptions as identified by Microsoft security intelligence solutions. IP Details are published to your Log Analytics workspace so you can create custom queries and put alerts on them. You can also access prepopulated queries from the traffic analytics dashboard.

The following table details public IP schema:

Field Format Comments
TableName AzureNetworkAnalyticsIPDetails_CL Table that contains traffic analytics IP details data.
SubType_s FlowLog Subtype for the flow logs. Use only "FlowLog", other values of SubType_s are for internal workings of the product.
FASchemaVersion_s 2 Schema version. Doesn't reflect network security group flow log version.
FlowIntervalStartTime_t Date and Time in UTC Start time of the flow log processing interval (time from which flow interval is measured).
FlowIntervalEndTime_t Date and Time in UTC End time of the flow log processing interval.
FlowType_s - AzurePublic
- ExternalPublic
- MaliciousFlow		 See Notes for definitions.
IP Public IP Public IP whose information is provided in the record.
Location Location of the IP - For Azure Public IP: Azure region of virtual network/network interface/virtual machine to which the IP belongs OR Global for IP 168.63.129.16.
- For External Public IP and Malicious IP: 2-letter country code where IP is located (ISO 3166-1 alpha-2).
PublicIPDetails Information about IP - For AzurePublic IP: Azure Service owning the IP or Microsoft virtual public IP for 168.63.129.16.
- ExternalPublic/Malicious IP: WhoIS information of the IP.
ThreatType Threat posed by malicious IP For Malicious IPs only: One of the threats from the list of currently allowed values (described in the next table).
ThreatDescription Description of the threat For Malicious IPs only. Description of the threat posed by the malicious IP.
DNSDomain DNS domain For Malicious IPs only. Domain name associated with the malicious IP.
Url URL corresponding to the malicious IP For Malicious IPs only
Port Port corresponding to the malicious IP For Malicious IPs only

List of threat types:

Value Description
Botnet Indicator detailing a botnet node/member.
C2 Indicator detailing a Command & Control node of a botnet.
CryptoMining Traffic involving this network address / URL is an indication of CyrptoMining / Resource abuse.
DarkNet Indicator of a Darknet node/network.
DDos Indicators relating to an active or upcoming DDoS campaign.
MaliciousUrl URL that is serving malware.
Malware Indicator describing a malicious file or files.
Phishing Indicators relating to a phishing campaign.
Proxy Indicator of a proxy service.
PUA Potentially Unwanted Application.
WatchList A generic bucket into which indicators are placed when it can't be determined exactly what the threat is or requires manual interpretation. WatchList should typically not be used by partners submitting data into the system.

Notes

  • In case of AzurePublic and ExternalPublic flows, customer owned Azure virtual machine IP is populated in VMIP_s field, while the Public IP addresses are populated in the PublicIPs_s field. For these two flow types, you should use VMIP_s and PublicIPs_s instead of SrcIP_s and DestIP_s fields. For AzurePublic and ExternalPublic IP addresses, we aggregate further, so that the number of records ingested to Log Analytics workspace is minimal. (This field will be deprecated. Use SrcIP_s and DestIP_s depending on whether the virtual machine was the source or the destination in the flow).
  • Some field names are appended with _s or _d, which don't signify source and destination but indicate the data types string and decimal respectively.
  • Based on the IP addresses involved in the flow, we categorize the flows into the following flow types:
    • IntraVNet: Both IP addresses in the flow reside in the same Azure virtual network.
    • InterVNet: IP addresses in the flow reside in two different Azure virtual networks.
    • S2S (Site-To-Site): One of the IP addresses belongs to an Azure virtual network, while the other IP address belongs to customer network (Site) connected to the virtual network through VPN gateway or ExpressRoute.
    • P2S (Point-To-Site): One of the IP addresses belongs to an Azure virtual network, while the other IP address belongs to customer network (Site) connected to the Azure Virtual Network through VPN gateway.
    • AzurePublic: One of the IP addresses belongs to an Azure virtual network, while the other IP address is an Azure Public IP address owned by Microsoft. Customer owned Public IP addresses aren't part of this flow type. For instance, any customer owned VM sending traffic to an Azure service (Storage endpoint) would be categorized under this flow type.
    • ExternalPublic: One of the IP addresses belongs to an Azure virtual network, while the other IP address is a public IP that isn't in Azure and isn't reported as malicious in the ASC feeds that traffic analytics consumes for the processing interval between “FlowIntervalStartTime_t” and “FlowIntervalEndTime_t”.
    • MaliciousFlow: One of the IP addresses belong to an Azure virtual network, while the other IP address is a public IP that isn't in Azure and is reported as malicious in the ASC feeds that traffic analytics consumes for the processing interval between “FlowIntervalStartTime_t” and “FlowIntervalEndTime_t”.
    • UnknownPrivate: One of the IP addresses belong to an Azure virtual network, while the other IP address belongs to the private IP range defined in RFC 1918 and couldn't be mapped by traffic analytics to a customer owned site or Azure virtual network.
    • Unknown: Unable to map either of the IP addresses in the flow with the customer topology in Azure and on-premises (site).

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