You can connect to the TG582 router’s command line interface using telnet which gives you a great level of control over this router. You need to be connected to the LAN side of the router, you cannot do this over the Internet (unless you are VPN’d to a PC on the local network the router is on). The default login username is “Administrator” (yes. uppercase ‘A’!) and the password is the web interface password (blank by default).
You will need to have the firmware file hosted on a web server somewhere, lets say the URL for this is http://myserver.com/tg582firmware.bin. The server this is hosted on doesn’t need to be on the local network with the router as long as the router has a working Internet connection.
Iissue this command in your router’s telnet interface:
software download url=http://myserver.com/tg582firmware.bin filetype=firmware
It may ask you for some other options, just leave them blank (by pressing the return key).
Then your router will download, reboot & upgrade itself.
Note: on the new TG588 & TG589 routers there is no need for this as you can simply upgrade firmware in the web interface. Some of these do have a command line interface but it is totally different to the TG582 and doesn’t seem to be very useful (yet).