How To: Netcat – Check for open ports with the command line

NetCat PortKitty Port-checking

When troubleshooting a network integration or any other connection issue in Linux, step one is usually a matter of checking to see if the network port on the other side is even responding.

Netcat -The network Swiss Army knife (Hobbit, not nmap)- is the right tool for the job.

Before we begin, NetCat needs to be installed.

# RHEL / CentOS
~$ yum install nc

# Debian / Ubuntu
~$ apt-get install nc

Once installed, you can invoke Netcat like so:
~$ nc [REMOTE_SERVER] [PORT]

Syntax:
[REMOTE_SERVER] – The server to be checked
[PORT] – The service/port to be checked

 

 


Connection to google.com 443 port [tcp/https] succeeded!

How To: Send and receive files with Ncat (formerly NetCat)

As with any application in Linux, piping the output from an application to a logfile or perhaps another application. Can sometimes clarify what is going on. It would be even better if you could “cat” any output over the Network (Ncat, get it?) to another computer. That is where Ncat comes in.

First, some basics

  • ncat The command in question
  • -v Verbose output, recommended for testing
  • -l Tells ncat to listen
  • -k Tells ncat to keep the connection up (ncat exits on client disconnect by default)
  • -n Tells ncat to skip DNS resolution (not necessary when connecting/listening on plain IP’s)
  • –ssl Tells ncat to send data encrypted with ssl (optional)
  • –send-only Tells ncat to only send data (optional)
  • –recv-only Tells ncat to only receive data (optional)

Now, some examples

  • [Server] $ncat -l 1025 > file.txt [Client] $cat file.txt | ncat [IP of Server] 1025 – Sends “file.txt” to the server over port 1025
  • [Server] $ncat -lkv 12345 > file.txt [Client] $cat file.txt | ncat [IP of Server] 12345 – Sends “file.txt” to the server over port 12345. The server will verbosely print what is going on, and keep the connection open when the client disconnects
  • [Server] $ncat -lkvn –recv-only 1337 > supersecretfile.txt [Client] $cat supersecretfile.txt | ncat –send-only –ssl [IP of Server] 1337 – Sends “supersecretfile.txt” to the server over port 1337. The server will verbosely print output, keep the connection open and skip resolving DNS. While the client sends the data encrypted over ssl

How To: Banner Grab With NetCat


Netcat is without any doubt my favorite security tool, it’s always in my toolbox alwayswith me, it comes in handy a few times. It’s the first tool I pick when I need to perform a banner grab, just connect and send some requests and see what it spits back at you (sometimes just random crap). In this tutorial i’ll show you how can perform one yourself and how easy it is. Continue reading How To: Banner Grab With NetCat

Disable The Translation Bar In Google Chrome/Chromium

OMG, Leave me alone!! For one freakin’ second leave me alone!! That annoying translation bar that keeps popping up every time i visit a website thats in another language than my own, but what if i already understand that language? Wouldn’t it be nice if you could just slam that annoying translation bar to hell? Well, you can’t, but you can disable it if you like :)

It’s very simple and i found the solution HERE, just follow the steps: go to Tools > Options > Under the Hood > Translate and deselect the box next to “Offer to translate pages that aren’t in a language I read”

Done!

Do you use Google Chrome/Chromium?