CODEWITHSUNDEEP
windowsdelphiwindows-firewalldelphi-12-athenswindows-firewall-api
Shaun Roselt
Shaun Roselt

Reputation: 3240

How to get a list of outbound firewall rule names?

I'm trying to build a function that would return a list of all the firewall outbound rules that I have on my computer, but I'm just not getting the function to work.

This is what I have currently:

function GetOutboundFirewallRuleNames: TStringList;
var
  i: Integer;
begin
  var ruleNames := TStringList.Create;

  // Initialize COM
  CoInitialize(nil);
  try
    try
      // Create an instance of the firewall policy
      var fwPolicy2: OleVariant := CreateOleObject('HNetCfg.FwPolicy2');

      // Loop through all rules to find the outbound rules
      for i := 1 to fwPolicy2.Rules.Count do
      begin
        var rule: OleVariant := fwPolicy2.Rules.Item(i - 1);
        if rule.Direction = 2 then // Outbound direction
        begin
          ruleNames.Add(rule.Name);
        end;
      end;

      Result := ruleNames;
    except
      on E: EOleException do
      begin
        ruleNames.Free;
        raise Exception.CreateFmt('Error accessing firewall rules: %s', [E.Message]);
      end;
      on E: Exception do
      begin
        ruleNames.Free;
        raise;
      end;
    end;
  finally
    // Uninitialize COM
    CoUninitialize;
  end;
end;

The errors I am getting are the following:

Project raised exception class EOleException with message 'The system cannot find the file specified'.

Project raised exception class Exception with message 'Error accessing firewall rules: The system cannot find the file specified'.

And the errors seems to happen on this line of code:

var rule: OleVariant := fwPolicy2.Rules.Item(i - 1);

I am also running the Delphi IDE as an administrator as well as my app as an administrator as well.

Could someone please help in assisting me in terms of what I'm doing wrong or what the correct way is to get a list of firewall outbound rule names? 🙏🏻

Upvotes: 0

Views: 88

Answers (1)

Ivan Yuzafatau
Ivan Yuzafatau

Reputation: 573

You can use the IEnumVARIANT interface for looping over rules. Reworked your example and this works for me:

procedure GetOutboundFirewallRuleNames(AStrings: TStrings);
var
  Enum: IEnumVARIANT;
  Value: LongWord;
  FwPolicy2, Rule: OleVariant;
begin
  // Initialize COM
  CoInitialize(nil);
  try
    try
      // Create an instance of the firewall policy
      FwPolicy2 := CreateOleObject('HNetCfg.FwPolicy2');
      Enum := IUnknown(FwPolicy2.Rules._NewEnum) as IEnumVARIANT;
      // Loop through all rules to find the outbound rules
      while Enum.Next(1, Rule, Value) = 0 do
      begin
        if Rule.Direction = 2 then // Outbound direction
          AStrings.Add(Rule.Name);
      end;
    except
      on E: EOleException do
        raise Exception.CreateFmt('Error accessing firewall rules: %s', [E.Message]);
      on E: Exception do
        raise;
    end;
  finally
    // Uninitialize COM
    CoUninitialize;
  end;
end;

Upvotes: 0

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