Configuring the VPC Flow Log Function¶
Scenarios¶
A Virtual Private Cloud (VPC) flow log captures information about the traffic going to and from your VPC. You can use flow logs to monitor network traffic, analyze network attacks, and determine whether security groups and firewall rules need to be modified.
You can obtain traffic details of VPC Network Interface Cards (NICs) from their logs on the LTS console.
This section describes how to configure VPC flow log reporting.
Constraints¶
A VPC is available.
Currently, only C3, M3, and S2 ECSs are supported.
Operation Process¶
Figure 1 Flowchart¶
Operations in Figure 1 are performed on different consoles:
Create log groups and log streams on the LTS console.
Create and view VPC flow logs on the VPC console.
Creating a Log Group¶
Log in to the management console.
Click Service List and choose Management & Deployment > Log Tank Service.
Figure 2 Log management¶
On the Log Management page, click Create Log Group.
Figure 3 Creating a log group¶
On the displayed page, enter a log group name.
Table 1 Parameter description¶ Parameter
Description
Example Value
Log Group Name
Specifies the log group name which must be globally unique. The configuration rules are as follows:
Must be a string of 1 to 64 characters.
Only allows uppercase and lowercase letters, digits, underscores (_), hyphens (-), and periods (.). The name cannot start with a period or underscore, or end with a period.
lts-group-7hjg
Log Retention Duration
Specifies the time period, in the unit of days, of storing logs in the LTS database. The default retention period for logs is seven days. Any logs stored longer than the retention period will be deleted.
7
Click OK.
Creating a Log Stream¶
To create a log stream in the log group, perform the following operations:
Log in to the management console.
Click Service List and choose Management & Deployment > Log Tank Service.
Click
next to the log group name to expand the log stream list.
Figure 4 Log stream list¶
Click Create Log Stream.
Figure 5 Creating a log stream¶
On the displayed page, enter a log stream name.
Table 2 Log stream parameters¶ Parameter
Description
Example Value
Log Stream Name
The log stream name must be unique in a log group. The configuration rules are as follows:
Must be a string of 1 to 64 characters.
Cannot start with a period (.) or underscore (_) or end with a period (.).
lts-topic-ncwm
Click OK. The log stream is created.
Creating a VPC Flow Log¶
Log in to the management console.
In the upper left corner of the management console, select the target region and project.
Choose Service List > Network > Virtual Private Cloud.
In the navigation pane on the left, choose VPC Flow Logs.
In the upper right corner, click Create VPC Flow Log. On the displayed page, configure parameters as prompted.
Figure 6 Creating a VPC flow log¶
Table 3 Parameter description¶ Parameter
Description
Example Value
Name
Specifies the VPC flow log name.
The VPC flow log name can contain a maximum of 64 characters, which may consist of letters, digits, underscores (_), hyphens (-), and periods (.). The name cannot contain spaces.
flowlog-495d
Resource Type
Specifies the resource type whose traffic is to be logged. You can select NIC, Subnet, or VPC.
NIC
Select NIC
Specifies the specific NIC whose traffic is to be logged. You can select only one NIC.
-Filter
All: specifies that both accepted and rejected traffic of the specified resource will be logged.
Accepted traffic: specifies that only accepted traffic of the specified resource will be logged. Accepted traffic refers to the traffic permitted by the security group or firewall.
Rejected traffic: specifies that only rejected traffic of the specified resource will be logged. Rejected traffic refers to the traffic not permitted by the firewall.
All
Log Group
Specifies the log group created in LTS.
lts-group-wule
Log Topic
Specifies the log stream created in LTS.
LogTopic1
Description
Provides supplementary information about the VPC flow log. This parameter is optional.
The VPC flow log description can contain a maximum of 255 characters and cannot contain angle brackets (< or >).
-Click OK.
Viewing a VPC Flow Log¶
The capture window is approximately 10 minutes, which indicates that a flow log record will be generated every 10 minutes. After creating a VPC flow log, you need to wait about 10 minutes before you can view the flow log record.
Log in to the management console.
In the upper left corner of the management console, select the target region and project.
Choose Service List > Network > Virtual Private Cloud.
In the navigation pane on the left, choose VPC Flow Logs.
Locate the target VPC flow log and click View Log Record in the Operation column to view information about the flow log record in LTS.
Figure 7 Viewing a log record¶
Figure 8 Viewing details of a log record¶
The flow log record is in the following format:
<version> <project-id> <interface-id> <srcaddr> <dstaddr> <srcport> <dstport> <protocol> <packets> <bytes> <start> <end> <action> <log-status>
Example 1: The following is an example of a flow log record in which traffic was allowed during the capture window:
1 5f67944957444bd6bb4fe3b367de8f3d 1d515d18-1b36-47dc-a983-bd6512aed4bd 192.168.0.154 192.168.3.25 38929 53 17 1 96 1548752136 1548752736 ACCEPT OK
Value 1 indicates the VPC flow log version. Traffic with a size of 96 bytes to NIC 1d515d18-1b36-47dc-a983-bd6512aed4bd during the past 10 minutes (from 16:55:36 to 17:05:36 on January 29, 2019) was allowed. A data packet was transmitted over the UDP protocol from source IP address 192.168.0.154 and port 38929 to destination IP address 192.168.3.25 and port 53.
Example 2: The following is an example of a flow log record in which no data was recorded during the capture window:
1 5f67944957444bd6bb4fe3b367de8f3d 1d515d18-1b36-47dc-a983-bd6512aed4bd - - - - - - - 1431280876 1431280934 - NODATA
Example 3: The following is an example of a flow log record in which records were skipped during the capture window:
1 5f67944957444bd6bb4fe3b367de8f3d 1d515d18-1b36-47dc-a983-bd6512aed4bd - - - - - - - 1431280876 1431280934 - SKIPDATA
Table 4 describes the fields of a flow log record.
Table 4 Log field description¶ Field
Description
Example Value
version
Specifies the VPC flow log version.
1
project-id
Specifies the project ID.
5f67944957444bd6bb4fe3b367de8f3d
interface-id
Specifies the ID of the NIC for which the traffic is recorded.
1d515d18-1b36-47dc-a983-bd6512aed4bd
srcaddr
Specifies the source IP address.
x.x.x.x
dstaddr
Specifies the destination IP address.
x.x.x.x
srcport
Specifies the source port of the traffic.
38929
dstport
Specifies the destination port of the traffic.
53
protocol
Specifies the Internet Assigned Numbers Authority (IANA) protocol number of the traffic. For details, see Assigned Internet Protocol Numbers.
17
packets
Specifies the number of packets transferred during the capture window.
1
bytes
Specifies the number of bytes transferred during the capture window.
96
start
Specifies the time, in Unix seconds, of the start of the capture window.
1548752136
end
Specifies the time, in Unix seconds, of the end of the capture window.
1548752736
action
Specifies the action associated with the traffic:
ACCEPT: The recorded traffic was permitted by the security group or firewall.
REJECT: The recorded traffic was not permitted by the firewall.
ACCEPT
log-status
Specifies the logging status of the VPC flow log:
OK: Data is logging normally to the chosen destinations.
NODATA: There was no network traffic to or from the NIC during the capture window.
SKIPDATA: Some flow log records were skipped during the capture window. This may be caused by an internal capacity constraint or an internal error.
OK
You can search for flow log records by keyword on the log stream details page on the LTS console.