New answers tagged sniffing
Depending on how the router's administrator panel is implemented you may be able to retrieve the page containing the list of connected devices with an appropriately crafted wget command. Check out wget options --user and --password. You can then extract the list from the resulting HTML file with tools like sed, awk or perl.
Getting that kind of data from the router itself might be tricky, if the router doesn't have a good interface for you to do it on. Failing that, I'd say just fire up nmap and do either a ping scan or an ARP scan of the network - if you want to integrate that with another application, there's an XML output option that you could run on a schedule and parse.
Top 50 recent answers are included