Introduction
Differences between Clear Text, Cryptography Protocols & VPNs
Clear-text:
Easy to intercept, eavesdrop & mangle.
Use clear-text only on trusted networks.
Cryptographic Protocols:
Protocol encrypts information transmitted to protect the communication.
Prevents eavesdropping.
Need to transmit clear-text anyways? Wrap your communication into a tunnel.
Protocol for Tunneling = VPN.
VPN:
A VPN uses cryptography to extend a private network over a public one.
Protected connection a to a a private network.
A VPN connection is needed for using the course Labs.
HTTP(s) Traffic Sniffing with Wireshark
There are 2 websites using HTTP and HTTPS respectively, differences in the communication can be checked through a sniffer as Wireshark and using the command 'Follow TCP Stream':
Basic Binary and Hexadecimal Arithmetic
Binary
1 + 1 = 10
111 + 1 = 1000
1101b=13d
Converting Decimal and to Binary
Divide by 2 and keep a not of the remainder iterating the same operation until the dividend is zero.
13d is 1011b:
1
13 / 2 = 6
1
2
6 / 2 = 3
0
3
2 / 2 = 1
1
4
1 / 2 = 0
1
Binary Operators
NOT
Negation
NOT 1101 = 0010
AND
if (both bits in the comparing position are ones) -> 1; else 0
1001 AND 1100 = 1000
OR
if (at least one of the bits is one) -> 1; else 0
1001 OR 1100 = 1101
XOR
if (just one of the bits is one) -> 1; else 0
1001 XOR 1100 = 0101
Hexadecimal
Hex
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
Dec
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0x3a1 = 3a1h = 929d
3 = 3
3 * 16^2
768
a = 10
10 * 16^1
160
1 = 1
1 * 16^0
1
Converting decimal to hexadecimal
Similar to converting decimal to binary: 1019d = 0x3FB
1019 / 16
63.6875
0.6875 * 16 = 11 (B)
63 / 16
3.9375
0.9375 * 16 = 15 (F)
3 / 16
0.1875
0.1875 * 16 = 3
0 / 16
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