LiSt Open Files (LSOF) is an excellent utility for managing and tracking network connections on your Linux system. This utility allows you to see what program is operating on an open port, which daemons have established connections, and what ports are open on your server. You can list open ports,… Continue Reading Linux lsof command.
Netsh allows you to display or modify the network configuration of a computer that is currently running. Netsh also allows you to run a group of commands in batch mode against a specified computer. Netsh can also save a configuration script in a text file for archival purposes. This feature… Continue Reading Using netsh command under windows xp.
One common method of denial-of-service attack ( DoS) involves saturating the target machine with external communications requests. If you want an indication of a denial of service (DoS) attack against your system’s , just run this command:
netstat -ant | grep SYN_RECV | wc -l
This command executes this steps. Show all tcp connections in numeric format… Continue Reading The indication of a denial of service (DoS) attack.
To display information about memory, we use the following command:
$ free -help
free: invalid option -- 'h'
usage: free [-b|-k|-m|-g] [-l] [-o] [-t] [-s delay] [-c count] [-V]
-b,-k,-m,-g show output in bytes, KB, MB, or GB
-l show detailed low and high memory statistics
-o use old format (no -/+buffers/cache line)
-t display total for RAM + swap
-s update every [delay] seconds
-c update [count] times
-V display version information and exit
$ free -mt
total used free shared buffers cached
Mem: 1002 758 243 0 46 355
-/+ buffers/cache: 357 644
Swap: 2015 0 2015
Total: 3018 758 2259
But if we want the data displayed in the terminal to be maintained, we will use:
$ watch --help
Usage: watch [-dhntv] [--differences[=cumulative]] [--help] [--interval=] [--no-title] [--version] <command></command>
-d, --differences[=cumulative] highlight changes between updates
(cumulative means highlighting is cumulative)
-h, --help print a summary of the options
-n, --interval= seconds to wait between updates
-v, --version print the version number
-t, --no-title turns off showing the header
The combination of the two args will solve our problem. Here is the final command:
$ watch -d free -mt
Here is the displayed result: It… Continue Reading How to display memory in real time on Linux systems.
I will present two examples to generate an md5 hash from an input string. The first example uses the openssl.
$ echo -n 'text to be encrypted' | openssl md5
The second example uses md5sum.
$ echo -n 'text to be encrypted' | md5sum
This is all.