Handshake - A request send to a destination to access it
IP Adress
- IP v4 shows your IP address in decimals
- IP v6 shows your IP address in hexadecimal
- IPv4 starting from 192.168 are all private IP addresses
- Large corporations use IP address starting from 10.0
MAC adress
The first 3 octets of MAC dress tell you about the vendor/company
To know how IP adress and MAC adress play a role in networking see OSI Canvas
TCP
- This is the main information transfer protocol and secure
- Used by almost all connections (browser, internet traffic, HTTP, FTP, telnet)
- Uses 3 way - handshake
- For 3 way - handshake usually the messages request is SYN and response is SYN/ACK and then you send an ACK to establish connections
- So basically TCP will know if data gets stolen is the middle
UDP
- Used for instant/fast connection (DNS etc..)
- Does not use handshake
- UDP doesn’t care about what happens to the data midway
Common Ports
TCP :
| Protocol | Port | Function |
|---|---|---|
| FTP | 21 | Uploads or access file in a server |
| Telnet | 23 | Used to log-in remotely |
| SSH | 22 | Same as Telnet but crypted |
| DNS | 53 | Converts domain name to IP adress |
| HTTP | 80 | Web adress |
| HTTPS | 443 | HTTP but crypted |
| SMB | 139 / 445 | File sharing |
UDP :
| Protocol | Port | Function |
|---|---|---|
| DNS | 53 | Converts domain name to IP adress |
| DHCP | 67 / 68 | It provides the IP addresses to devices across the network |
OSI MODEL
| Level | Property | Devices |
|---|---|---|
| Level 1 | Physical | Wires, cables |
| Level 2 | Data Link | MAC address, Switches, Router, Wifi Access cards |
| Level 3 | Network | IP address, Router, Hosts, IOT devices |
| Level 4 | Transport | Ports, TCP, UDP |
| Level 5 | Session | Session Management |
| Level 6 & 7 | —————————————— | —————————————— |
GET and POST request
| GET request | POST request |
|---|---|
| This request usually modifies the URL | This request doesn’t change the URL |
| Parameters are visible in the URL, making it less secure for sensitive data | Parameters are not visible in the URL, making it more secure for sensitive data |
| Used to retrieve data from a server | Used to send data to the server to create or update resources |
| Usually used in search pages | Usually used to store usernames and passwords |
Other Protocols :
-
DNS - It converts Domain Names into IP addresses Ex - www.google.com —> 121.29.8.9
-
ARP - It is used to get a computers MAC address through its IP address by sending a ARP packet to every device in that network and only the particular device responds back telling its MAC address
-
Subnet mask - It is used to divide a IP address into 2 parts : Its network address and host address
Ex - IP address 121.29.8.9 subnet mask 255.255.255.0 means Network address is 121.29.8.0 and host address is .9