Mirror is available in two versions, Mirror as a shared network folder, and Mirror as an HTTP server. Detailed configuration instructions for each method can be found below:

Mirror as a shared network folder

The principle of this method is that virus signature updates are saved to a shared network folder and then distributed across the LAN. It is not required that the computer which downloads these updates be the same as the computer which stores them. The shared network folder containing the updates can be located elsewhere, such as a Novell Netware server or Linux server).

Important! This method may be limited by the number of computers that can connect to a shared folder at one time. If this is a potential limitation in your network environment, use of the second method – Mirror as an HTTP server – is recommended.

Installation:

1. From the ESET NOD32 Antivirus Control Center, click Update → Mirror and then click Setup in the right pane. Select the Create update mirror check box at the bottom of the window.
   
   
2. In the Available versions section at the top, select all versions of NOD32 for which updates will be downloaded from the Internet, by selecting the appropriate check boxes.
   
   

   

   
   Important! All operating system versions which will run NOD32 in your local network should be selected.
    

3. Click the Folder button and locate the folder which will be used to store update copies. If the folder is located on another computer, enter the path to the shared network directory (When entering a path to a network directory, please use the UNC format. For example, if a folder named MIRROR is located on a server named SERVER, the path should be //SERVER/MIRROR).
    
4. To configure access to the mirror folder, insert the domain username and password into the Login name and Password fields. If the mirror folder is located on a computer with an older operating system such as Windows 95/98/ME – the username and password is not required. We recommend leaving these fields blank to avoid future complications. However, for Windows NT/2000/XP/2003 systems, the Login name and Password must be supplied. Use the format DOMAINUSER_NAME, or WORKGROUPUSER_NAME.
   
   
   Client Workstation Configuration:
   
   
5. On client workstations, change the URL of the update server. To do so, navigate to NOD32 Control Center → Update and click Setup. Click the Servers... button, click Add and enter the path to the update location. As mentioned above, it should be in the format //SERVER/MIRROR. Click OK twice to save changes and return to the Setup of Automatic Update window. From the Server: drop-down menu, select the mirror path you just created.
   
   If the mirror folder (shared network folder) is located on a computer running Windows NT/2000/XP/2003, each client computer which will access the mirror folder for updates must supply a username and password. Fill in the User name and Password fields in the Setup of Automatic Update window. This username account must have 'read' access rights to the mirror folder (We recommend creating a special account dedicated for local updates of NOD32. For example, if you created NODUSER as a member of a domain named COMPANY, then the format of your username will be as follows: COMPANY/NODUSER).
    
6. Click OK to save the changes. To test the configuration, click Update → Update → Update Now from the NOD32 Control Center. NOD32 should not report any error messages or ask you to enter your username and password again.

NOTE: Please make sure that silent mode is not activated. Silent mode suppresses all messages that do not require user intervention, including update error messages. To read more about general system configuration of NOD32, please click NOD32 Control Center settings.

Mirror as an HTTP server

A computer using the Mirror as an HTTP server method to download update files from the Internet and also functions as a NOD32 update server for clients in the LAN. The primary advantage of this method is that client workstations need no authentication data to access the update server.

NOTE: This method is limited by the number of users downloading updates. The recommended maximum number of users is 100. If you want more users, you can create more update servers or use another HTTP server (e.g. Apache).

Installation:

1. From the NOD32 Control Center, click Update → Mirror and then click Setup in the right pane. Select the Create update mirror and Enable access to files via the HTTP protocol check boxes.
   
   NOTE: All operating system versions which will run NOD32 in your local network should be selected.
   
   
2. In the Available versions section at the top, select all versions of NOD32 for which updates will be downloaded from the Internet, by selecting the appropriate check boxes.
    
3. Click the Folder button and locate the folder which will be used to store update copies, available via the HTTP protocol (The path must lead to the local computer, not to a network folder!). Click OK to save the changes.
    
4. In order to download update files to the folder immediately, before the pre-scheduled time, select Update Now in the section Update.
   
   
   Client Workstation Configuration:
   
   
5. On client workstations, change the URL of the update server. change the URL of the update server. To do so, navigate to NOD32 Control Center → Update and click Setup. Click the Servers... button, click Add and enter: http://server_IP_address:8081, or http://server_name:8081, where server_IP is the actual name and IP address of your server. Click OK twice to save changes and return to the Setup of Automatic Update window. From the Server: drop-down menu, select the new server you just created.
    
6. Both server and clients configuration is complete. To test the communication, open the NOD32 Control Center on a client computer and click Update Now. NOD32 should not report any error messages or ask you to enter your username and password again.

NOTE: Please make sure that silent mode is not activated. Silent mode suppresses all messages that do not require user intervention, including update error messages. To read more about general system configuration of NOD32, please click NOD32 Control Center Settings.

Related:

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?