Remotely logging on to machines is a very common task The most common programs to login were telnet, rsh and rlogin Networks, and LANs in particular, are insecure If a group of computers are connected in a lab, any computer in the lab can see all the data sent across the network Authentication is the process of proving an identity To access a computer, you provide an account name and something that proves you are allowed to access it Passwords are the normal method for authentication Passwords must be protected and this is difficult across a network telnet and friends send login names and passwords in plain text

A malicious program can snoop data and passwords Security is as much a human problem as it is a technology problem Users often: use easy to guess passwords save passwords in a file on the hrd drive use the same password for accounts, email, websites These behaviours lead to insecurity

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