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Adding an Application to the Exception list on the Windows Firewall


Here is a class that can help with adding an Application to the Exception list on the Windows Firewall. I am sure it can be tidy up some what and improved but it does the job You will need to reference the hnetcfg.dll that can be found in the system32 directory.

Paul Campbell, IdiomSoftware


///
/// Allows basic access to the windows firewall API.
/// This can be used to add an exception to the windows firewall
/// exceptions list, so that our programs can continue to run merrily
/// even when nasty windows firewall is running.
///
/// Please note: It is not enforced here, but it might be a good idea
/// to actually prompt the user before messing with their firewall settings,
/// just as a matter of politeness.
///

///
/// To allow the installers to authorize idiom products to work through
/// the Windows Firewall.
///

public class FirewallHelper
{
#region Variables
///
/// Hooray! Singleton access.
///

private static FirewallHelper instance = null;

///
/// Interface to the firewall manager COM object
///

private INetFwMgr fwMgr = null;
#endregion
#region Properties
///
/// Singleton access to the firewallhelper object.
/// Threadsafe.
///

public static FirewallHelper Instance
{
get
{
lock (typeof(FirewallHelper))
{
if (instance == null)
instance = new FirewallHelper();
return instance;
}
}
}
#endregion
#region Constructivat0r
///
/// Private Constructor. If this fails, HasFirewall will return
/// false;
///

private FirewallHelper()
{
// Get the type of HNetCfg.FwMgr, or null if an error occurred
Type fwMgrType = Type.GetTypeFromProgID("HNetCfg.FwMgr", false);

// Assume failed.
fwMgr = null;

if (fwMgrType != null)
{
try
{
fwMgr = (INetFwMgr)Activator.CreateInstance(fwMgrType);
}
// In all other circumnstances, fwMgr is null.
catch (ArgumentException) { }
catch (NotSupportedException) { }
catch (System.Reflection.TargetInvocationException) { }
catch (MissingMethodException) { }
catch (MethodAccessException) { }
catch (MemberAccessException) { }
catch (InvalidComObjectException) { }
catch (COMException) { }
catch (TypeLoadException) { }
}
}
#endregion
#region Helper Methods
///
/// Gets whether or not the firewall is installed on this computer.
///

///
public bool IsFirewallInstalled
{
get
{
if (fwMgr != null &&
fwMgr.LocalPolicy != null &&
fwMgr.LocalPolicy.CurrentProfile != null)
return true;
else
return false;
}
}

///
/// Returns whether or not the firewall is enabled.
/// If the firewall is not installed, this returns false.
///

public bool IsFirewallEnabled
{
get
{
if (IsFirewallInstalled && fwMgr.LocalPolicy.CurrentProfile.FirewallEnabled)
return true;
else
return false;
}
}

///
/// Returns whether or not the firewall allows Application "Exceptions".
/// If the firewall is not installed, this returns false.
///

///
/// Added to allow access to this metho
///

public bool AppAuthorizationsAllowed
{
get
{
if (IsFirewallInstalled && !fwMgr.LocalPolicy.CurrentProfile.ExceptionsNotAllowed)
return true;
else
return false;
}
}

///
/// Adds an application to the list of authorized applications.
/// If the application is already authorized, does nothing.
///

///
/// The full path to the application executable. This cannot
/// be blank, and cannot be a relative path.
///
///
/// This is the name of the application, purely for display
/// puposes in the Microsoft Security Center.
///
///
/// When applicationFullPath is null OR
/// When appName is null.
///

///
/// When applicationFullPath is blank OR
/// When appName is blank OR
/// applicationFullPath contains invalid path characters OR
/// applicationFullPath is not an absolute path
///

///
/// If the firewall is not installed OR
/// If the firewall does not allow specific application 'exceptions' OR
/// Due to an exception in COM this method could not create the
/// necessary COM types
///

///
/// If no file exists at the given applicationFullPath
///

public void GrantAuthorization(string applicationFullPath, string appName)
{
#region Parameter checking
if (applicationFullPath == null)
throw new ArgumentNullException("applicationFullPath");
if (appName == null)
throw new ArgumentNullException("appName");
if (applicationFullPath.Trim().Length == 0)
throw new ArgumentException("applicationFullPath must not be blank");
if (applicationFullPath.Trim().Length == 0)
throw new ArgumentException("appName must not be blank");
if (applicationFullPath.IndexOfAny(Path.InvalidPathChars) >= 0)
throw new ArgumentException("applicationFullPath must not contain invalid path characters");
if (!Path.IsPathRooted(applicationFullPath))
throw new ArgumentException("applicationFullPath is not an absolute path");
if (!File.Exists(applicationFullPath))
throw new FileNotFoundException("File does not exist", applicationFullPath);
// State checking
if (!IsFirewallInstalled)
throw new FirewallHelperException("Cannot grant authorization: Firewall is not installed.");
if (!AppAuthorizationsAllowed)
throw new FirewallHelperException("Application exemptions are not allowed.");
#endregion

if (!HasAuthorization(applicationFullPath))
{
// Get the type of HNetCfg.FwMgr, or null if an error occurred
Type authAppType = Type.GetTypeFromProgID("HNetCfg.FwAuthorizedApplication", false);

// Assume failed.
INetFwAuthorizedApplication appInfo = null;

if (authAppType != null)
{
try
{
appInfo = (INetFwAuthorizedApplication)Activator.CreateInstance(authAppType);
}
// In all other circumnstances, appInfo is null.
catch (ArgumentException) { }
catch (NotSupportedException) { }
catch (System.Reflection.TargetInvocationException) { }
catch (MissingMethodException) { }
catch (MethodAccessException) { }
catch (MemberAccessException) { }
catch (InvalidComObjectException) { }
catch (COMException) { }
catch (TypeLoadException) { }
}

if (appInfo == null)
throw new FirewallHelperException("Could not grant authorization: can't create INetFwAuthorizedApplication instance.");

appInfo.Name = appName;
appInfo.ProcessImageFileName = applicationFullPath;
// ...
// Use defaults for other properties of the AuthorizedApplication COM object

// Authorize this application
fwMgr.LocalPolicy.CurrentProfile.AuthorizedApplications.Add(appInfo);
}
// otherwise it already has authorization so do nothing
}
///
/// Removes an application to the list of authorized applications.
/// Note that the specified application must exist or a FileNotFound
/// exception will be thrown.
/// If the specified application exists but does not current have
/// authorization, this method will do nothing.
///

///
/// The full path to the application executable. This cannot
/// be blank, and cannot be a relative path.
///
///
/// When applicationFullPath is null
///

///
/// When applicationFullPath is blank OR
/// applicationFullPath contains invalid path characters OR
/// applicationFullPath is not an absolute path
///

///
/// If the firewall is not installed.
///

///
/// If the specified application does not exist.
///

public void RemoveAuthorization(string applicationFullPath)
{

#region Parameter checking
if (applicationFullPath == null)
throw new ArgumentNullException("applicationFullPath");
if (applicationFullPath.Trim().Length == 0)
throw new ArgumentException("applicationFullPath must not be blank");
if (applicationFullPath.IndexOfAny(Path.InvalidPathChars) >= 0)
throw new ArgumentException("applicationFullPath must not contain invalid path characters");
if (!Path.IsPathRooted(applicationFullPath))
throw new ArgumentException("applicationFullPath is not an absolute path");
if (!File.Exists(applicationFullPath))
throw new FileNotFoundException("File does not exist", applicationFullPath);
// State checking
if (!IsFirewallInstalled)
throw new FirewallHelperException("Cannot remove authorization: Firewall is not installed.");
#endregion

if (HasAuthorization(applicationFullPath))
{
// Remove Authorization for this application
fwMgr.LocalPolicy.CurrentProfile.AuthorizedApplications.Remove(applicationFullPath);
}
// otherwise it does not have authorization so do nothing
}
///
/// Returns whether an application is in the list of authorized applications.
/// Note if the file does not exist, this throws a FileNotFound exception.
///

///
/// The full path to the application executable. This cannot
/// be blank, and cannot be a relative path.
///
///
/// The full path to the application executable. This cannot
/// be blank, and cannot be a relative path.
///
///
/// When applicationFullPath is null
///

///
/// When applicationFullPath is blank OR
/// applicationFullPath contains invalid path characters OR
/// applicationFullPath is not an absolute path
///

///
/// If the firewall is not installed.
///

///
/// If the specified application does not exist.
///

public bool HasAuthorization(string applicationFullPath)
{
#region Parameter checking
if (applicationFullPath == null)
throw new ArgumentNullException("applicationFullPath");
if (applicationFullPath.Trim().Length == 0)
throw new ArgumentException("applicationFullPath must not be blank");
if (applicationFullPath.IndexOfAny(Path.InvalidPathChars) >= 0)
throw new ArgumentException("applicationFullPath must not contain invalid path characters");
if (!Path.IsPathRooted(applicationFullPath))
throw new ArgumentException("applicationFullPath is not an absolute path");
if (!File.Exists(applicationFullPath))
throw new FileNotFoundException("File does not exist.", applicationFullPath);
// State checking
if (!IsFirewallInstalled)
throw new FirewallHelperException("Cannot remove authorization: Firewall is not installed.");

#endregion

// Locate Authorization for this application
foreach (string appName in GetAuthorizedAppPaths())
{
// Paths on windows file systems are not case sensitive.
if (appName.ToLower() == applicationFullPath.ToLower())
return true;
}

// Failed to locate the given app.
return false;

}

///
/// Retrieves a collection of paths to applications that are authorized.
///

///
///
/// If the Firewall is not installed.
///

public ICollection GetAuthorizedAppPaths()
{
// State checking
if (!IsFirewallInstalled)
throw new FirewallHelperException("Cannot remove authorization: Firewall is not installed.");

ArrayList list = new ArrayList();
// Collect the paths of all authorized applications
foreach (INetFwAuthorizedApplication app in fwMgr.LocalPolicy.CurrentProfile.AuthorizedApplications)
list.Add(app.ProcessImageFileName);

return list;
}
#endregion
}

///
/// Describes a FirewallHelperException.
///

///
///
///

public class FirewallHelperException : System.Exception
{
///
/// Construct a new FirewallHelperException
///

///
public FirewallHelperException(string message)
: base(message)
{ }
}


Written By: host  Date Posted: 10/08/2005 10:27 AM
Number of Views: 1153


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