Creating EC2 Ingress rule in C#

Question

I'm trying to create an ingress rule in C# and I'm getting an error at runtime.
Here's the relevant code:
 `

///////////BEGIN Set Vars//////////////////////
            ///////////////////////////////////////////////
            Amazon.EC2.AmazonEC2Client ec2Client = new Amazon.EC2.AmazonEC2Client();
            Amazon.EC2.Model.AuthorizeSecurityGroupIngressRequest secRequest = new 
           **Amazon.EC2.Model.AuthorizeSecurityGroupIngressRequest();
            Amazon.EC2.Model.IpPermission ipPerm = new Amazon.EC2.Model.IpPermission();
            Amazon.EC2.Model.IpRange ipRange = new Amazon.EC2.Model.IpRange();
            List ipRangeList = new List();

///////////////////////////////////////////////
            ///////////END Set Vars////////////////////////
            ///////////////////////////////////////////////

///////////////////////////////////////////////
            ///////////BEGIN IP Range//////////////////////
            ///////////////////////////////////////////////

ipRange.CidrIp = "5.5.5.10/32";
            ipRange.Description = "My new IP rule";
            ipRangeList.Add(ipPerm);
            ///////////////////////////////////////////////
            ///////////END IP Range////////////////////////
            ///////////////////////////////////////////////

///////////////////////////////////////////////
            ///////////BEGIN IP Perms//////////////////////
            ///////////////////////////////////////////////
            ipPerm.IpProtocol = "tcp";
            ipPerm.ToPort = 3389;
            ipPerm.FromPort = 3389;
            ipPerm.Ipv4Ranges.AddRange((IEnumerable)ipRangeList);
            ///////////////////////////////////////////////
            ///////////END IP Perms////////////////////////
            ///////////////////////////////////////////////`

If I just try to add ipRange as a range to *ipPerm*, the precompiler complains that it needs to be type of *List*.

When I use the code above and cast it to *List*, the precompiler gets happy, but I get a runtime error:

**  Message=Unable to cast object of type 'System.Collections.Generic.List`1[Amazon.EC2.Model.IpPermission]' to type 'System.Collections.Generic.IEnumerable`1[Amazon.EC2.Model.IpRange]'.
  Source=System.Private.CoreLib
  StackTrace:
   at System.Runtime.CompilerServices.CastHelpers.ChkCastAny(Void* toTypeHnd, Object obj)
   at AWSFirewall.Program.Main(String[] args) in C:\Users\SeanMcCown\source\repos\AWSFirewall\Program.cs:line 44**

Answer

You are trying to cast incompatible types, so the .NET runtime generates an exception. You want to add a list of `IpPermission` objects into a list of `IpRange` objects, which is not possible.

Please refer to the AWS SDK documentation about [Updating security groups](https://docs.aws.amazon.com/sdk-for-net/v3/developer-guide/authorize-ingress.html).

There, you can find a code snippet that shows you how to add an ingress rule to a security group:

async Task AddIngressRuleAsync(IAmazonEC2 eC2Client, string groupID, string ipAddress, int port)
    {
      // Create an object to hold the request information for the rule.
      // It uses an IpPermission object to hold the IP information for the rule.
      var ingressRequest = new AuthorizeSecurityGroupIngressRequest { GroupId = groupID };
      ingressRequest.IpPermissions.Add(new IpPermission
      {
        IpProtocol = "tcp",
        FromPort = port,
        ToPort = port,
        Ipv4Ranges = new List { new IpRange { CidrIp = ipAddress } }
      });

// Create the inbound rule for the security group
      var responseIngress = await eC2Client.AuthorizeSecurityGroupIngressAsync(ingressRequest);
      Console.WriteLine($"
New RDP rule was written in {groupID} for {ipAddress}.");
      Console.WriteLine($"Result: {responseIngress.HttpStatusCode}");
    }

You can then use this method to update the security group with your desired permissions:

var ec2Client = new Amazon.EC2.AmazonEC2Client();
    var sgId = "your-security-group-id";
    var cidr = "5.5.5.10/32";
    var port = 3389;
    await AddIngressRuleAsync(ec2Client, sgId, cidr, port);

Creating EC2 Ingress rule in C#

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