(re) configuring hidden VPN Profile properties

Using MEM (Intune) we can automatically deploy VPN profiles to our users’ managed devices directly.

The set of parameters that can be configured in MEM is extremely limited compared to what actually ends up on the rasphone.pbk file (VPN Profile) on a Windows client.

Example of a .pbk file for an Azure P2S VPN connection with Conditional Access/cert based SSO:

[AzureVirtualNetwork]
Encoding=1
PBVersion=6
Type=4
AutoLogon=0
UseRasCredentials=1
LowDateTime=-1117351264
HighDateTime=30942358
DialParamsUID=927022140
Guid=AABC7C8342FD91458105A961BE471F8E
VpnStrategy=7
ExcludedProtocols=8
LcpExtensions=1
DataEncryption=256
SwCompression=1
NegotiateMultilinkAlways=1
SkipDoubleDialDialog=0
DialMode=0
OverridePref=15
RedialAttempts=0
RedialSeconds=0
IdleDisconnectSeconds=0
RedialOnLinkFailure=0
CallbackMode=0
CustomDialDll=
CustomDialFunc=
CustomRasDialDll=%windir%\system32\cmdial32.dll
ForceSecureCompartment=0
DisableIKENameEkuCheck=0
AuthenticateServer=0
ShareMsFilePrint=1
BindMsNetClient=1
SharedPhoneNumbers=0
GlobalDeviceSettings=0
PrerequisiteEntry=
PrerequisitePbk=
PreferredPort=VPN2-0
PreferredDevice=WAN Miniport (IKEv2)
PreferredBps=0
PreferredHwFlow=0
PreferredProtocol=0
PreferredCompression=0
PreferredSpeaker=0
PreferredMdmProtocol=0
PreviewUserPw=0
PreviewDomain=0
PreviewPhoneNumber=0
ShowDialingProgress=0
ShowMonitorIconInTaskBar=1
CustomAuthKey=13
CustomAuthData=314442430D000405C000000020005005C0000001500000014000000A8985D3A65E5E5C4B2D7D66D40C6DD2FB19C5436020001001230FE0006000100FCD02C00
CustomAuthData=3BCB684FDAE6ED1B763A3EDEB989B12C95EFFAFFD330281E75F1C671B03CDD800FF0844797977764005000500
AuthRestrictions=128
IpPrioritizeRemote=0
IpInterfaceMetric=1
IpHeaderCompression=1
IpAddress=0.0.0.0
IpDnsAddress=172.1.230.4
IpDns2Address=172.1.230.5
IpWinsAddress=0.0.0.0
IpWins2Address=0.0.0.0
IpAssign=1
IpNameAssign=2
IpDnsFlags=0
IpNBTFlags=1
TcpWindowSize=0
UseFlags=2
IpSecFlags=0
IpDnsSuffix=
Ipv6Assign=1
Ipv6Address=::
Ipv6PrefixLength=0
Ipv6PrioritizeRemote=1
Ipv6InterfaceMetric=0
Ipv6NameAssign=1
Ipv6DnsAddress=::
Ipv6Dns2Address=::
Ipv6Prefix=0000000000000000
Ipv6InterfaceId=0000000000000000
DisableClassBasedDefaultRoute=1
DisableMobility=0
NetworkOutageTime=0
IDI=
IDR=
ImsConfig=0
IdiType=0
IdrType=0
ProvisionType=0
PreSharedKey=
CacheCredentials=0
NumCustomPolicy=0
NumEku=0
UseMachineRootCert=0
Disable_IKEv2_Fragmentation=0
PlumbIKEv2TSAsRoutes=0
NumServers=0
RouteVersion=1
NumRoutes=0
NumNrptRules=0
AutoTiggerCapable=0
NumAppIds=0
NumClassicAppIds=0
SecurityDescriptor=
ApnInfoProviderId=
ApnInfoUsername=
ApnInfoPassword=
ApnInfoAccessPoint=
ApnInfoAuthentication=1
ApnInfoCompression=0
DeviceComplianceEnabled=0
DeviceComplianceSsoEnabled=0
DeviceComplianceSsoEku=
DeviceComplianceSsoIssuer=
WebAuthEnabled=0
WebAuthClientId=
FlagsSet=0
Options=0
DisableDefaultDnsSuffixes=0
NumTrustedNetworks=0
NumDnsSearchSuffixes=0
PowershellCreatedProfile=0
ProxyFlags=0
ProxySettingsModified=0
ProvisioningAuthority=
AuthTypeOTP=0
GREKeyDefined=0
NumPerAppTrafficFilters=0
AlwaysOnCapable=0
DeviceTunnel=0
PrivateNetwork=0

NETCOMPONENTS=
ms_msclient=1
ms_server=1

MEDIA=rastapi
Port=VPN2-0
Device=WAN Miniport (IKEv2)

DEVICE=vpn
PhoneNumber=azuregateway-12341ef-4922-4edc-a492-589b3e547c58-1ba19cb9ae52.vpn.azure.com
AreaCode=
CountryCode=0
CountryID=0
UseDialingRules=0
Comment=
FriendlyName=
LastSelectedPhone=0
PromoteAlternates=0
TryNextAlternateOnFail=1

Modifying VPN Profile settings

To allow admins further customization of these settings, I’ve written a Proactive Remediation script that can customize any VPN profile property to any value you specify.

In our case, we used it to set IpInterfaceMetric, which defaults to 0, causing ambiguously routed traffic to never prefer the VPN connection (since this is a split tunnel connection). Setting it to 1 resolved our DNS/routing issues to certain private endpoints in our Azure environment.

Code / git link: https://gitlab.com/Lieben/assortedFunctions/-/blob/master/set-vpnConnectionInterfaceMetric.ps1