Modem Security
A modem allows one computer (the client) to establish a connection to another (the server) by dialing the server's telephone number. This is sometimes viewed as being insecure because there is no authentication of the call originator. One way to increase security is to enforce a modem callback protocol, which usually proceeds as a series of steps:
- The client computer calls the server computer.
- After a greeting the client identifies itself, usually with a user name.
- The server then disconnects the call.
- Based upon the user name and a list of users' phone numbers, the server will then establish a second call back to the client computer.
- The client computer, expecting this returned call, will then answer and communications between the two computers will proceed normally.
Sometimes callback modem setups can also be used for billback purposes, allowing the originator to avoid lengthy toll charges.
Read more about this topic: Callback (telecommunications)
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