In ESET NOD32 Antivirus 2.7 and earlier, the LAN Update (Mirror) functionality was enabled through a separate modified client download. The Mirror functionality is now incorporated into the Business client download of ESET Smart Security and ESET NOD32 Antivirus 3.0 and later. In addition, the ESET Remote Administrator (ERA) license file (nod32.lic) is now required in order to enable the Mirror functionality.

Before you begin configuring the Mirror, the following three files should be downloaded and installed:

-ESET Remote Administrator Sever
-ESET Remote Administrator Console
-ESET Smart Security or ESET NOD32 Antivirus

To add the ERA license file (nod32.lic) to the system:

1. Open the main program window by clicking the ESET icon next to the system clock or by clicking Start → All Programs → ESET→ ESET Smart Security or ESET NOD32 Antivirus.
    
2. Press the F5 key to open the Advanced Setup window.
    
3. In the Advanced Setup tree, click Miscellaneous → Licenses and then click the Add... button.
    
4. Locate and double-click the nod32.lic file.
    
5. From the Advanced Setup tree, click Update and then click the Setup... button in the Advanced Setup window. The Mirror tab should now be visible; this will allow you to configure the Mirror functionality.

NOTE: The Mirror can also be configured through the ESET Remote Administrator Console (ERAC) by clicking Tools → Server Options... → Update tab. Port 2221 is used for communication with the Mirror server.

Related:

How do I update ESET Remote Administrator with a new license file? (3.0)

How do I install ESET Remote Administrator and configure a Mirror server? (3.0)

How do I configure ESET clients to access the Mirror server? (3.0)

How do I create a dual update profile configuration with ESET Remote Administrator? (3.0)