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How can I tell how many devices are connected to my Router?
Out of curiousity, how can I go about telling how many devices are connected to my router at any given time? (Cisco router).
I have obviously changed the default password to login to the router. But am still curious.
It depends on if they are using DHCP or have a static configuration. Your DHCP service keeps track of what IP addresses it is handing out to which MAC addresses, so you can see there. If they have static addresses, you have to do a multicast ping for the whole network range and see who responds. Otherwise, if it is your router, you are the network admin, and should be able to trace the cables and know who physically connected. You can program it to only assign addresses to specific devices, to keep unauthorized people from getting a usable address, and blacklist all addresses but those handed out by DHCP or the devices you have given static addresses yourself. Really, if you have a Cisco router, you should have an idea on how to configure it. A CCNA certification really comes in handy if you need something more capable than an off-the-shelf home router.
Linksys products are dumbed-down routers for home use. A Cisco router has a command line configuration tool, Linksys just uses a web browser HTTP interface. Cisco owns Linksys, but the routers don't configure the same way, and you don't have access to many of the functions of a Linksys without custom firmware. There's a big difference between a Linksys branded router and a Cisco branded one, which is why they push the Upgrade to Cisco program.
All you can do with that is log into the router via HTTP and see what MAC addresses have been assigned DHCP configurations. If someone sets up a static address, you cannot see them without doing a multicast ping and hoping they are set to respond to it. If you want to block wireless access to your router, set a WEP or WPA password, and set a MAC address filter so only devices you are actually using via wireless are allowed to connect to the network. EVen then, wireless isn't 100% secure, as people can still read the radio traffic and figure out your password from that, and if a device turns off they can clone the MAC address of it and connect that way. If you can catch who it is, and you've had your router protected with a wireless network password, you can file action against them for unauthorized network tresspass. Use of a password-protected wireless network without permission is illegal.