SDL episode 26

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Secure Digital Life #26

Recorded August 1, 2017 at G-Unit Studios in Rhode Island!

Episode Audio

Coming Soon!


  • Doug White
    Cybersecurity professor, President of Secure Technology, and Security Weekly network host.
  • Russell Beauchemin
    Cybersecurity & Network Security Program Advisor and Director of Instructional Support & Learning Innovation at Roger Williams University.
  • IP Addresses

    What are IPV4 addresses?

    4 8 bit addresses which are written in decimal numbers, separated by . 2^32 - 1 possible addresses == 4,294,967,295

    Establish the range of possible numbers 0 - 255 in 8 bits

    All IP came from the DARPA 1969 project to build ARPANET and were drafted into the IEEE 802 project (802.2) adopted in 1983 by ISO.

    IPs were assigned in blocks originally (they are all sold now, so enjoy) The idea was GOV and BIG CORP were "class A" University and Enterprise were "class B" everyone else was "class c"

    Here's how they did it: from 0000 0000 to 0111 1111 (127) is class A from 1000 0000 to 1011 1111 (191) is class B from 1100 0000 ro 1101 1111 (223) is class C That's it.

    Now, there are special addresses that are reserved == Private Class A == Private Class B == Private Class C == Loopback or HOME/.HERE address You should use these on your networks since it eliminates the 4 billion address problem

    So, this breaks into public addresses and private addresses.

    You can't attach public addresses to the internet unless you own them and they are expensive. This is called a STATIC IP.

    Using 1 Static Public IP, you can map MANY private ips into that single address using "PAT". This means that most any static ip can have approx 65000 private ips mapped onto it. This is why IPV4 stopped being the problem.

    All this meant that IPV6 which is a 128 bit address was no longer that "necessary".

    Next Time, the Dreaded Subnet MASK!