or certain combinations of the above. A modem by itself provides none of the functions of a router. It merely allows ATM or Ethernet or PPP traffic to be transmitted across telephone lines, cable wires, optical fibers, or wireless radio frequencies. On the receiving end is another modem that re-converts the transmission format back into digital data packets. This allows network bridging using telephone, cable, optical, and radio connection methods. The modem also provides handshake protocols, so that the devices on each end of the connection are able to recognize each other. However, a modem generally provides few other network functions.
A USB modem plugs into a single PC and allows a connection of that single PC to a WAN. If properly configured, the PC can also function as the router for a home LAN.
An internal modem can be installed on a single PC, also allowing that single PC to connect to a WAN. Again, the PC can be configured to function as a router for a home LAN.
A wireless access point can function in a similar fashion to a modem. It can allow a direct connection from a home LAN to a WAN, if a wireless router or access point is present on the WAN as well. However, many modems now incorporate the features mentioned below and thus are appropriately described as residential gateways.
It may also provide other functions such as Dynamic DNS. Most routers are self-contained components, using internally stored firmware. They are generally OS-independent, i.e., they can be accessed with any operating system. Wireless routers perform the same functions as a router, but also allow connectivity for wireless devices with the LAN, or between the wireless router and another wireless router.
Security
Low-cost production and requirement for user friendliness makes the home routers vulnerable to network attacks, which in the past resulted in large clusters of such devices being taken over and used to launch DDoS attacks. A majority of the vulnerabilities were present in the web administration consoles of the routers, allowing unauthorised control either via default passwords, vendor backdoors, or web vulnerabilities.
