Read Chapter 6 - A Brief TCP/IP Primer

  1. Using the ethereal program. Day #2. Headers (envelopes or folders) followed by headers followed by more headers, finally followed by the actual data or payload information. Ethernet header, IP header, TCP header, HTTP header example from class.

  2. Encrypting strings using the PERL crypt function. This function is often used to encrypt passwords. (See Wednesday c3.html for more PERL and Caeser cipher illustrated for UNI Panthers plaintext).
    > perl -e '$text=crypt "Hello", "AC"; print $text . "\n\n";'
    > perl -e '$text=crypt "HellO", "AC"; print $text . "\n\n";'
    > perl -e '$text=crypt "HellO", "DC"; print $text . "\n\n";'

  3. What is cryptography? Conventional cryptography and Julius Caeser. Cipher text and clear text.

  4. What kind of cryptography will stop your kid sister from reading your files and WHAT is Cryptography? Its hard to decipher your handwriting? Its hard to decipher cipher text, but no deciphering is needed for plain text.

  5. The OSI Seven Layer model protocol stack.