What is HTTP?
HTTP is an internet protocol used to transfer information from local client browsers to internet hosted web servers. The browser sends a message request to a specific web server using a valid address via HTTP and the message response with content is sent back to the client using the same protocol and a status.
The two main HTTP request methods are GET and POST.
GET method used to retrieve data with the request coming in from the URL via a query string.
The data is added to the end of the URL www.site.com/search?name=value
POST method used when the client page sends form data to the web server and is sent in the body of that message.
Data sent via HTTP uses plain text which is readable by anyone.
Most web sites use HTTPS which encrypts the data sent and received.
Data is secured using a security protocol called TLS (Transport Layer Security).
Application layer protocol that is sent over TCP, or over a TLS-encrypted TCP connection.
TLS, is a security protocol used for sending secure data over the internet. It will encrypt the messages between web servers and client browsers.
The Transmission Control Protocol (TCP) is a main protocol of the Internet and is used in conjunction with the Internet Protocol (IP). TCP/IP.
TCP provides reliable, ordered, and error-checked delivery of a stream
of octets (bytes) between applications running on hosts communicating
via an IP network.
Internet applications like World Wide Web, email and ftp depend on TCP. Security protocols like SSL/TLS run on top of TCP.
Functions can be called in response to an HTTP request.
Make a GET, POST or other HTTP request to a URL provided>t.
HyperText Transfer Protocol (HTTP)
HTTP is an asymmetric request-response client-server protocol.
Sends a request message to an HTTP server.
Returns a response message.
Browser
Issue a URL from your browser to get a web resource using HTTP,
Browser turns the URL into a request message
Send it to the HTTP server.
Server interprets the request message.
Returns you an appropriate response message.
Uniform Resource Locator (URL)
A URL (Uniform Resource Locator) is used to uniquely identify a resource over the web.
URL has the following syntax:
protocol://hostname:port/path-and-file-name
There are 4 parts in a URL:
Protocol: The application-level protocol used by the client and server,e.g., HTTP, FTP, and telnet.
Hostname: The DNS domain name (e.g., www.nowhere123.com)
or IP address (e.g., 192.128.1.2) of the server.
Port: The TCP port number that the server is listening for incoming
requests from the clients.
Path-and-file-name: The name and location of the requested
resource, under the server document base directory.
The port number was not specified in the URL, and takes on the default number, which is TCP port 80 for HTTP. The path and file name for the resource to be located
is "/docs/index.html".
Communication Ports
Communication ports allow for data/commands to enter linux/Unix servers. The IP address allows this traffic to get to the right server, the port number connects you to the service on that machine.
In Unix and Linux, these ports are the endpoints for network communications, managed by the kernel and used by the Transport Layer protocols: TCP (connection-oriented) and UDP (connectionless).
Every network connection is defined by a "socket," which is the combination of an IP Address and a Port Number.
Range: Port numbers range from 0 to 65535.
Ports (0 – 1023) Reserved for system services (e.g., HTTP, SSH, FTP). Only the root user can start services on these ports.
Ports
21 (FTP): File transfer protocol
22 (SSH): Secure Shell for remote login.
80 (HTTP) / 443 (HTTPS): Standard web traffic.
25 (SMTP): Email routing
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