Linux Ask!

Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.

Jul 282010

What is the difference between ip address and


Sometimes when using the netstat command, which print out something like

# netstat -ntpl
(No info could be read for "-p": geteuid()=1001 but you should be root.)
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0    *               LISTEN      -

What is the real meaning of

In fact, this special IP means "all the IP addresses on the local machine". So if you have seen a service listening on, it means you can connect to the service using any IP addresses of the machine.

Jun 182010

Simple file encryption with OpenSSL


You have a single file (input.txt), and you want to encrypt it with a password, it is easy with OpenSSL.

# openssl aes-128-cbc -salt -in input.txt-out input.aes

Enter the password twice.

When you want to decrypt it, use the command.

# openssl aes-128-cbc -d -salt -in input.aes -out output.txt