In the first two lines, you can see that the network
was restarted. The next line shows that the user named chris tried and failed to get to the FTP
server on this system from a computer at address 10.0.0.5 (he typed the wrong password and
authentication failed). The last line shows chris using the su command to become root user.
By occasionally reviewing the messages and secure files, it??™s possible to catch a cracking attempt
before it is successful. If you see an excessive number of connection attempts for a particular service,
especially if they are coming from systems on the Internet, you may be under attack.
Using Secure Shell Tools
The Secure Shell (ssh) tools are a set of client and server applications that allow you to do basic
communications (remote login, remote copy, remote execution, and so on) between remote computers
and your Linux system. Because communication is encrypted between the server (typically
the sshd daemon process) and clients (such as ssh, scp, and sftp), these tools are inherently more
secure than similar, older UNIX tools such as rsh, rcp, and rlogin.
Most Linux systems include Secure Shell clients, while many include the sshd server as well. If you
are using the Fedora or Red Hat Enterprise Linux distributions, for example, the following client and
server software packages include the ssh software: openssh, openssh-clients, and openssh-server
packages.
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