Explain how hackers get into a system.
Hackers are a threat to any machine on the Internet.
The explicit purpose of hackers may not be to cause harm to your machine; they might simply be playing around or looking for software to steal. However, hackers will cost you system resources, administration time, and possibly material damage, because once your system has been compromised, you can no longer trust its operability. The following describes some of the various ways hackers gain access to systems.
The most common way that hackers gain access to a machine is by obtaining a system user's password. One way to obtain passwords is through social engineering, such as masquerading as a systems engineer to illicitly obtain passwords of users .
In other instances, hackers simply find user passwords lying around on a piece of paper. Finally, users sometimes reuse passwords, making it easier for a cracker to enter the system.
By far the most common way to retrieve a password is to sniff it from an insecure public network using a password
The sniffer logs all pairs it finds, for the later use of the cracker.
If a user ever connects from across the Internet, then his/her password may be compromised in this manner.
The following diagram reviews sniffers in more depth.