The vCenter Server must only send NetFlow traffic to authorized collectors.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-258938	SRG-APP-000516	VCSA-80-000271	SV-258938r961863_rule	2024-12-16	2

Description
The distributed virtual switch can export NetFlow information about traffic crossing the switch. NetFlow exports are not encrypted and can contain information about the virtual network, making it easier for a man-in-the-middle attack to be executed successfully. If NetFlow export is required, verify that all NetFlow target Internet Protocols (IPs) are correct.

ℹ️ Check
If distributed switches are not used, this is not applicable. To view NetFlow Collector IPs configured on distributed switches: From the vSphere Client, go to "Networking". Select a distributed switch >> Configure >> Settings >> NetFlow. View the NetFlow pane and verify any collector IP addresses are valid and in use for troubleshooting. or From a PowerCLI command prompt while connected to the vCenter server, run the following command: Get-VDSwitch \| select Name,@{N="NetFlowCollectorIPs";E={$_.ExtensionData.config.IpfixConfig.CollectorIpAddress}} To view if NetFlow is enabled on any distributed port groups: From the vSphere Client, go to "Networking". Select a distributed port group >> Manage >> Settings >> Policies. Go to "Monitoring" and view the NetFlow status. or From a PowerCLI command prompt while connected to the vCenter server, run the following command: Get-VDPortgroup \| Select Name,VirtualSwitch,@{N="NetFlowEnabled";E={$_.Extensiondata.Config.defaultPortConfig.ipfixEnabled.Value}} If NetFlow is configured and the collector IP is not known and documented, this is a finding.

ℹ️ Check

If distributed switches are not used, this is not applicable. To view NetFlow Collector IPs configured on distributed switches: From the vSphere Client, go to "Networking". Select a distributed switch >> Configure >> Settings >> NetFlow. View the NetFlow pane and verify any collector IP addresses are valid and in use for troubleshooting. or From a PowerCLI command prompt while connected to the vCenter server, run the following command: Get-VDSwitch | select Name,@{N="NetFlowCollectorIPs";E={$_.ExtensionData.config.IpfixConfig.CollectorIpAddress}} To view if NetFlow is enabled on any distributed port groups: From the vSphere Client, go to "Networking". Select a distributed port group >> Manage >> Settings >> Policies. Go to "Monitoring" and view the NetFlow status. or From a PowerCLI command prompt while connected to the vCenter server, run the following command: Get-VDPortgroup | Select Name,VirtualSwitch,@{N="NetFlowEnabled";E={$_.Extensiondata.Config.defaultPortConfig.ipfixEnabled.Value}} If NetFlow is configured and the collector IP is not known and documented, this is a finding.

✔️ Fix
To remove collector IPs, do the following: From the vSphere Client, go to "Networking". Select a distributed switch >> Configure >> Settings >> NetFlow. Click "Edit". Remove any unknown collector IPs. or From a PowerCLI command prompt while connected to the vCenter server, run the following commands: $dvs = Get-VDSwitch dvswitch \| Get-View ForEach($vs in $dvs){ $spec = New-Object VMware.Vim.VMwareDVSConfigSpec $spec.configversion = $vs.Config.ConfigVersion $spec.IpfixConfig = New-Object VMware.Vim.VMwareIpfixConfig $spec.IpfixConfig.CollectorIpAddress = "" $spec.IpfixConfig.CollectorPort = "0" $spec.IpfixConfig.ActiveFlowTimeout = "60" $spec.IpfixConfig.IdleFlowTimeout = "15" $spec.IpfixConfig.SamplingRate = "0" $spec.IpfixConfig.InternalFlowsOnly = $False $vs.ReconfigureDvs_Task($spec) } Note: This will reset the NetFlow collector configuration back to the defaults. To disable NetFlow on a distributed port group, do the following: From the vSphere Client, go to "Networking". Select a distributed port group >> Configure >> Settings >> Policies. Click "Edit". Click the "Monitoring" tab. Change "NetFlow" to "Disabled". or From a PowerCLI command prompt while connected to the vCenter server, run the following commands: $pgs = Get-VDPortgroup \| Get-View ForEach($pg in $pgs){ $spec = New-Object VMware.Vim.DVPortgroupConfigSpec $spec.configversion = $pg.Config.ConfigVersion $spec.defaultPortConfig = New-Object VMware.Vim.VMwareDVSPortSetting $spec.defaultPortConfig.ipfixEnabled = New-Object VMware.Vim.BoolPolicy $spec.defaultPortConfig.ipfixEnabled.inherited = $false $spec.defaultPortConfig.ipfixEnabled.value = $false $pg.ReconfigureDVPortgroup_Task($spec) }

✔️ Fix

To remove collector IPs, do the following: From the vSphere Client, go to "Networking". Select a distributed switch >> Configure >> Settings >> NetFlow. Click "Edit". Remove any unknown collector IPs. or From a PowerCLI command prompt while connected to the vCenter server, run the following commands: $dvs = Get-VDSwitch dvswitch | Get-View ForEach($vs in $dvs){ $spec = New-Object VMware.Vim.VMwareDVSConfigSpec $spec.configversion = $vs.Config.ConfigVersion $spec.IpfixConfig = New-Object VMware.Vim.VMwareIpfixConfig $spec.IpfixConfig.CollectorIpAddress = "" $spec.IpfixConfig.CollectorPort = "0" $spec.IpfixConfig.ActiveFlowTimeout = "60" $spec.IpfixConfig.IdleFlowTimeout = "15" $spec.IpfixConfig.SamplingRate = "0" $spec.IpfixConfig.InternalFlowsOnly = $False $vs.ReconfigureDvs_Task($spec) } Note: This will reset the NetFlow collector configuration back to the defaults. To disable NetFlow on a distributed port group, do the following: From the vSphere Client, go to "Networking". Select a distributed port group >> Configure >> Settings >> Policies. Click "Edit". Click the "Monitoring" tab. Change "NetFlow" to "Disabled". or From a PowerCLI command prompt while connected to the vCenter server, run the following commands: $pgs = Get-VDPortgroup | Get-View ForEach($pg in $pgs){ $spec = New-Object VMware.Vim.DVPortgroupConfigSpec $spec.configversion = $pg.Config.ConfigVersion $spec.defaultPortConfig = New-Object VMware.Vim.VMwareDVSPortSetting $spec.defaultPortConfig.ipfixEnabled = New-Object VMware.Vim.BoolPolicy $spec.defaultPortConfig.ipfixEnabled.inherited = $false $spec.defaultPortConfig.ipfixEnabled.value = $false $pg.ReconfigureDVPortgroup_Task($spec) }