azure powershell

# Virtual network
$RG1         = "resource_west_eu_api_test"
$VNet1       = "west-Eu-Api-2"
$Location1   = "West Europe"
$VNet1Prefix = "10.50.0.0/16"
$VNet1ASN    = 65010
$Gw1         = "virutal-gateway"

# On-premises network - LNGIP1 is the VPN device public IP address
$LNG1        = "VPNsite1"
$LNGprefix1  = "10.100.102.0/24"
$LNGIP1      = "195.215.105.8"

# Connection
$Connection1 = "VNet1ToSite1"

New-AzLocalNetworkGateway -Name $LNG1 -ResourceGroupName $RG1 `
  -Location $Location1 -GatewayIpAddress $LNGIP1 -AddressPrefix $LNGprefix1
  
$vng1 = Get-AzVirtualNetworkGateway -Name $GW1  -ResourceGroupName $RG1
$lng1 = Get-AzLocalNetworkGateway   -Name $LNG1 -ResourceGroupName $RG1

 
New-AzVirtualNetworkGatewayConnection -Name $Connection1 -ResourceGroupName $RG1 `
  -Location $Location1 -VirtualNetworkGateway1 $vng1 -LocalNetworkGateway2 $lng1 `
  -ConnectionType IPsec -SharedKey "Azure@!b2C3" -ConnectionProtocol IKEv2
  
  #to show key
  #Get-AzVirtualNetworkGatewayConnectionSharedKey `
  #-Name $Connection1 -ResourceGroupName $RG1
  
  #to change the key
  #Set-AzVirtualNetworkGatewayConnectionSharedKey `
  #-Name $Connection1 -ResourceGroupName $RG1 `
  #-Value "Azure@!_b2=C3"
  
$connection = Get-AzVirtualNetworkGatewayConnection -Name $Connection1 ` -ResourceGroupName $RG1
$newpolicy  = New-AzIpsecPolicy ` -IkeEncryption AES256 -IkeIntegrity SHA256 -DhGroup DHGroup2 `
   -IpsecEncryption AES128 -IpsecIntegrity SHA1 -PfsGroup PFS2048 `
   -SALifeTimeSeconds 14400 -SADataSizeKilobytes 102400000

Set-AzVirtualNetworkGatewayConnection -VirtualNetworkGatewayConnection $connection `
  -IpsecPolicies $newpolicy