Question: I'm setting up a P2S configuration on an Azure VPN Gateway.
I'm attempting to use machine certificate authentication and IKEv2.
I'm using the built in Windows 10 (1909) client and self generated certificates using powershell.

I can make the connection work using DH Group 2, however my connection fails once I switch DH Group to ECP256. I receive the error 'Error (13801) IKE Authentication credentials are unacceptable.'

Initial analysis suggested the certificate needed to be of type ECP so I generate the certificate as follows:

```
New-SelfSignedCertificate -Type Custom `
  -Subject "***" `
  -CertStoreLocation "Cert:\LocalMachine\My" `
  -Signer $cert `
  -TextExtension @("2.5.29.37={text}1.3.6.1.5.5.7.3.2") `
  -KeyExportPolicy Exportable `
  -KeyAlgorithm ECDSA_nistP256 `
  -CurveExport CurveName `
  -HashAlgorithm sha256

```

Can anyone suggest a possible resolution?

Answer: 
For your first question:

To list the names of the executables, which were opening these connections just add the parameter "-b" like this: `netstat -a -b`
There is also a parameter "-o", which shows yout the pid of the process associated with the network connection.

For your second question:

0.0.0.0 means all ip addresses on the local machine. Your netstat is showing this ip address, because you have services that are listening on all ipaddresses/network interfaces of your computer.
However, there is also local the address 23.20.0.70, which is the source address your computer is using when communicating with peers itself. Since your computer establishes the connections with a specific source address, 0.0.0.0 wouldn't make any sense in this context as a source address.
You might have heard that everything in Linux is a file (of sorts). Network ports are the same. Most of the programs like `netstat` or `ss` go through respective directory under `/proc` to find ports that are being used by at least one process and get their state and info, so they don't provide info on unused ports.

This for example, will give you list of all ports that are being listened to by a local process:

```
netstat -lntp

```

more info about params in <https://linux.die.net/man/8/netstat>