My Problem

I tried many different option to access a list in Central Administation from a web part in my application. Of course the problem is that the application pool acccount cannot access the list and there are many variations of access denied that I found on my way….

Your solution

// Get the Url for Central admin

SPAdministrationWebApplication caWebApp = Microsoft.SharePoint.Administration.SPAdministrationWebApplication.Local;
// open the list Service
Lists listService = new Lists();
listService.Url = caWebApp.Sites[0].RootWeb.Url + “/_vti_bin/Lists.asmx”;

// Set the credentials to use

listService.UseDefaultCredentials = true;
listService.PreAuthenticate = true;

Hopefully this will help someone else one day.