Microsoft Active Directory Code Snippet

Authenticating an Active Directory user:-

public bool IsUserAuthenticated (string strAdPath, string strDomain, string strUserName, string strPassword)
{
    DirectoryEntry directoryEntry = new DirectoryEntry(string strAdPath, string strDomain+@"\"+strUserName,strPassword);

    Object obj = directoryEntry.NativeObject;
    DirectorySearcher directorySearcher = new DirectorySearcher(directoryEntry);
    directorySearch.Filter ="(SAMAccountName = " + strUserName + ")";
    directorySearch.PropertiesToLoad.Add("cn");
    SearchResult searchResult = directorySearch.FindOne();

    if (searchResult ==null)
    {
      return false; // not authenticated
    }
    else
    {
      return true; // authenticated
    }

} 


Searching from Active Directory Server:-

public string[] SearchAD(string strLdapPath, string strCN, string strDomainName,string strSearchFilter)
{
     ArrayList arrayStrList = new ArrayList()
     string[] strSearch= new string[0];
     int i = 0;
     string strLdapString = strLdapPath+ "/CN="+strCN+";DC="+strDomainName;
     DirectoryEntry directoryEntry = new DirectoryEntry (strLdapString);
     DirectorySearcher directorySearcher = new DirectorySearcher (directoryEntry);
     directorySearch.Filter = strSearchFilter;
     foreach (SearchResult sr in directorySearcher.FindAll())
     {
         arrayStrList.Add(sr.GetDirectoryEntry().Path);
         i++;
     }
     strSearch = (string[])arrayStrList.ToArray(typeof(string));
     return strSearch;
}  

Reading LDAP properties:-

public string[] GetLdapProperties(string strLdapPath, string strCN, string strDomainName)
{
    ArrayList arrayStrList = new ArrayList()
    string[] strProperties = new string[0];
    int i = 0;
    string strLdapString = strLdapPath+ "/CN="+strCN+";DC="+strDomainName;
    DirectoryEntry directoryEntry = new DirectoryEntry (strLdapString);
     foreach (string strProperty in directoryEntry.Properties.PropertyNames)
     {
         arrayStrList.Add(strProperty);
         i++;
     }
     strProperties = (string[])arrayStrList.ToArray(typeof(string));
     return strProperties;
} 

Reference Link:-

http://it.toolbox.com/blogs/programming-life/integrating-your-net-app-with-active-directory-server-8655 

https://support.microsoft.com/en-us/kb/316748 

https://msdn.microsoft.com/en-us/library/ff649227.aspx 

https://msdn.microsoft.com/en-us/library/ff650307.aspx