Top 30 Nmap Command Examples For Sys/Network Admins

Posted on in Categories Command Line Hacks, Howto, Networking, Security last updated January 13, 2017

Nmap is short for Network Mapper. It is an open source security tool for network exploration, security scanning and auditing. However, nmap command comes with lots of options that can make the utility more robust and difficult to follow for new users.

The purpose of this post is to introduce a user to the nmap command line tool to scan a host and/or network, so to find out the possible vulnerable points in the hosts. You will also learn how to use Nmap for offensive and defensive purposes.

diff Command: Colorize Output On The Unix / Linux Command Line

Posted on in Categories Command Line Hacks, Programming, Web Developer last updated November 26, 2012

The diff command compare files line by line and displays a list of changes between two file. You can use diff command to:

  1. See the changes between one version of a file.
  2. Compare two configuration or program files.
  3. Create a patch file which can be applied with the Linux / Unix program patch.

Say hello to colordiff

colordiff is a wrapper for diff and produces the same output as diff but with coloured syntax highlighting at the command line to improve readability. colordiff has been tested on various flavours of Linux and under OpenBSD, but should be broadly portable to other systems.

Testing HTTP Status: 206 Partial Content and Range Requests

Posted on in Categories Cloud Computing, Command Line Hacks, Howto, Networking, Web Developer last updated November 17, 2012

The HTTP 2xx class of status codes indicates the action requested by the client was received, and processed successfully. HTTP/1.1 200 OK is the standard response for successful HTTP requests. When you type in the browser you will get this status code. The HTTP/1.1 206 status code allows the client to grab only part of the resource by sending a range header. This is useful for:

  1. Understanding http headers and protocol.
  2. Troubleshooting network problems.
  3. Troubleshooting large download problems.
  4. Troubleshooting CDN and origin HTTP server problems.
  5. Test resuming interrupted downloads using tools like lftp or wget or telnet.
  6. Test and split a large file size into multiple simultaneous streams i.e. download a large file in parts.

Linux ifdata Command: See Network Interface Info Without Parsing ifconfig Output

Posted on in Categories Command Line Hacks, Debian Linux last updated December 12, 2012

Reading an IP address in a shell script requires many time and various Linux distributions stores IP address in different text files. So most of us end up writing shell pipes/scripts to get the information using ifconfig | grep 'inet addr:'| grep -v '' | cut -d: -f2 | awk '{ print $1}' syntax. There is an alternative to ifconfig+shell pipe hack – ifdata command. It is a little know tool that can be used to check for the existence of a network interface and find out info about your interface such as IP, netmask, MTU and much more. No need to write shell pipes and fetch information via ifconfig or ip command. This command is designed to be easily used by a shell script.