It depends on how many interfaces of router are connected to other networks. If a router is connected to two network, it will have 2 IP addresses. In a router having 4 ports it can connect to maximum 4 networks. In this case it will have 4 IP addresses.
The number of ports vary with the router - some as few as 4, and some many more than that.
A router will typically support between 4 and 8 ports. For additional ports, a standard Ethernet switch can be connected to one of the ports.
65536 virtual ports. Port number is a 16 bit number, so there are 2^16 (65536) ports for a NAT router.
You have to setup a router and open the ports in the router for this purpose. But Pacenet have blocked many ports so you can go to their local office and ask them to open the ports.
2 Ports on the router however you can add more cards to the device. In a 2821 you can add 4 cards such as WICs and in a 2811 you can add 2 cards.
It depends on how many subnets you have and how many ports you router has. Usually each port in router is devoted to on subnet, you can do math for your situation.
The Netgear WGR614 has four wired ports, which is probably enough for most home networks.
The Router only has one M.A.C Address and One IP Address But, the Router can have many Connections ( Devices using the network ) That may shoe up as their IP Addresses. But the Router only Has One IP Address
The Cisco router 2811 comes in one speed which is 10/100. It has two ports and is a great wired router for small to medium business IP solutions and needs.
You should be able to check how many computers are connected to your router, in the router settings. Most likely you can find it in "Status" for wireless network or for all networks. You check MAC addresses for all your computers connected to the router and compare it with those in the list. In that way you know if you have some "guests". You find out who connected to your router will be much harder and require special software and training.PS: you can use MAC filter to block "guests".
A router or switch.
It may vary somewhat by the firewall or router you are using, but theoretically, every port from 1 to 65535 can be forwarded.