For Legend look here


On Unix systems you can get and configure the network from the command line.
There are also some commands, to test and analyze the local connections.

  • Pinging a host and outputing the results:

    > ping 

    This sends ECHO Requests to the specified HOST.
    Usefull for:

    1. to see if a system is available on the network
    2. to check if the network is configured correct.
      The command:
    > ping

    Will check if your computer can resolve the domain to an ip
    and then it will check if there is a system with that IP.

  • Listing ip addresses of all network interfaces:

    1. Compatible on nearly all unix based systems:

      > ifconfig
    2. On reasonable modern linux systems:

      > ip addr
  • Getting routing information:
    Routing, determines which interface to use to send and recieve traffic

    1. Unix systems:

      • IPv4
      > netstat -rn

      Hint: -r means: show routing table, -n show information as numbers,
      the last part is sometimes important, to avoid additional DNS request and
      response waits.

    • IPv6
      > netstat -f inet6 -rn
    1. Linux systems:
      • IPv4
        > ip route
    • IPv6
      > ip -6 route
  • Display of all active listening ports:

    > netstat -pnltu
  • Fetching whois information for domain:

    > whois domain
  • Fethcing DNS information for domain:

    > dig domain
  • Downloading a file:

    > wget file
  • Curl is a command line tool used to transfer data using any supported protocols
    As default, curl will output the response it got to the command line

    > curl option domain


    > curl
    > curl[1-20].jpeg


SSH or Secure Shell is used to securely gain command line access to systems
over non secure networks.

  • Connection to a host as a user:

    > ssh user@host
    • Example:
      > ssh pi@
  • Connection to a host on specific port as a user:

    > ssh -p port user@host
  • In order to enable a passwordless login you can use:
    This will copy the public key of the local ssh id to a special file
    authorized_keys in .ssh/ of the home folder of the user

    HINT: This requires that the next command was done before

    > ssh-copy-id user@host
  • SSH is able to use a private/public cryptographic key-pair for
    To generate such a key-pair, the following command can be used:

    > ssh-keygen -b 4096

    This will generate a 4096 bit length RSA key.
    It will also ask for a password to secure the key.