Connect an Android tablet to ethernet
Your Galaxy tab 8.9 connectivity specifications don't include wired Ethernet:

╔════════════════════════╦══════════════════════╗
║ Connectivity           ║                      ║
╠════════════════════════╬══════════════════════╣
║ WiFi                   ║ WiFi 802.11 a/b/g/n  ║
║ USB                    ║ USB 2.0 H/S          ║
║ Bluetooth              ║ Bluetooth 3.0        ║     
╚════════════════════════╩══════════════════════╝


To solve your issue a simple USB to Ethernet adapter would suffice, but as pointed out on the first comment on this answer, your device uses a proprietary connector, so an initial adapter is required:

Samsung Galaxy Tab™ USB &amp; SD Connection Kit



Another pertinent issue as mentioned, relating an Android driver and the support for USB to Ethernet adapters, but this Plugable USB 2.0 10/100 Ethernet Adapter (ASIX AX88772 Chipset), as mentioned on their support forum might help you.



From Amazon:

Plugable USB 2.0 to 10/100 Fast Ethernet LAN Network RJ45 Adapter (ASIX AX88772 chipset)