The requested resource does not have the "Access-Control-Allow-Origin" header - Ionic 2

I have a rest webservice and now I want to make a post request from the app frontend from the ionic 2 user to the authentication method.

In my login component I have:

...this._restClient.post(
                'authentication',
                body,
                (data) => this.handleSuccessAuthenticate(data),
                (data) => this.handleErrorAuthenticate(data)
            );...

      

        
        
        
      

    

On my provider, my _restClient code is:

public post(resource: string, data: Object, onSuccess: restClient, onError: callbackRestClient) {
        var httpResult: Observable<Response>;


        if (data === null) {
            httpResult = this._http.post(this.getUrl(resource), '{}', { headers: this.getHeaders() });
        } else {
            httpResult = this._http.post(this.getUrl(resource), JSON.stringify(data), { headers: this.getHeaders() });
        }


        this.handleResult(httpResult, onSuccess, onError);
    }

      

        
        
        
      

    

I also have a private method for setting headers:

   private getHeaders() {
        var headers = new Headers();
        headers.append('Accept', 'application/json');
        headers.append('Content-Type', 'application/json');
        headers.append('Access-Control-Allow-Origin', '*');
        headers.append('Access-Control-Allow-Credentials', 'true');
        headers.append("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE");
        headers.append("Access-Control-Allow-Headers", "Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token");

        return headers;
    }

      

        
        
        
      

    

I have a classic message:

Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource

      

        
        
        
      

    

What am I doing wrong?