#Configuration# How to add custom applications to block them using application policy

  

*Product: Sangfor NSF

*Version: Sangfor NSF 8.0.85

  

*1. Introduction

  

1.1 User Scenario

  

Nowadays it’s important to have control over the traffic that these protected clients do (even on unwanted applications that the user can use on business assets during work time).

  

But some applications use well-known ports to operate (for example TeamViewer, Skype, Hide. me, and so on).

  

If we want to deny this application, it’s impossible to apply a firewall rule that blocks a specific port and protocol without causing network issues for clients.

  

A solution to this scenario is to create a Custom Application to permit Sangfor NSF to inspect traffic and block unwanted traffic packets to block specific applications on specific clients within your network.

  

1.2 Requirements

  

1. The user's network has Sangfor NSF as a firewall.

  

2. You must know how the application that you need to block works (type of traffic, ports used, and destinations) to build an identikit on the firewall that permits you to know it and block it.

  

3. You need to have some clients and applications to block (in this guide we see how to block a custom application that we named test for a specific client that has a static IP)

  

*2. Configuration Guide

  

In this guide, we’ll see how to create a rule for a specific endpoint to block one custom application.

  

2.1 Blocking client applications with NSF policy

  

2.1.1 Create custom application Signatures

  

We need to add a setting about our custom application that we need to block it on the firewall.

  

To do so, we can go to the following web ui section:

                                            
  

On this page, we can add a new application signature (on this guide we call it test) that has all the behavior information related to our application that we want to block with NSF (think it as a sort of fingerprint).

  

Complete the information as follows:

2.1.2 Create application policy

  

At this point, we need to create an application control policy to filter out packets coming from our custom test application.

  

To achieve this, you must go to this section of NSF’s web UI and choose to create an Application Control policy:

  

Policies -> Application Control -> Policies -> Add

  

On the new policy, we need to choose a policy group and position to ensure that this policy works as expected (for example, we set the default-policy group policy).

  

During application policy creation, when you select the corresponding src. Address voice, you can create a network object that identifies the client which you want to block custom test application.

           
  

In this guide, I add a single IP related to a specific client:

  

After adding this information, you can click Save and select this client on the previous menu about new policy creation.

  

At this point, it’s important to specify the destination of the application traffic that we want to block and the custom application we created before.

  

  

On the above screenshot click on Applications, select the Newly Created Applications on the previous step, and click Save.

  

Now at the bottom of this page, we define the behavior of our policy and a schedule (if needed)

  

Now click Save to complete the policy creation.

  

Now you can see if there are some hits about the newly created policy.

  

*3. Precaution

  

Keep in mind that if you have some DHCP clients, I suggest you create a network object related to a specific network instead.

This article is written by Enrico Vanzetto who is a technical engineer and has much experience and a better understanding of Sangfor network secure (NGAF), HCI, Endpoint Secure, VDI, and Cyber Command products. If you want to know more about him, you can follow him.

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